# 200: Capacity Planning ## 200.1 Measure and Troubleshoot Resource Usage (weight: 6) {% hint style="success" %} Candidates should be able to measure hardware resource and network bandwidth, identify and troubleshoot resource problems. **Key Knowledge Areas:** * Measure CPU usage. * Measure memory usage. * Measure disk I/O. * Measure network I/O. * Measure firewalling and routing throughput. * Map client bandwidth usage. * Match / correlate system symptoms with likely problems. * Estimate throughput and identify bottlenecks in a system including networking. **The following is a partial list of the used files, terms and utilities:** * iostat * iotop * vmstat * netstat * ss * iptraf * pstree, ps * w * lsof * top * htop * uptime * sar * swap * processes blocked on I/O * blocks in * blocks out {% endhint %} ### Measuring System Resource Usage * `iostat`: Report on CPU statistics and input/output statistics for devices and partitions. Provided by the `sysstat` package. By default, the command generates two reports: CPU and device utilization. ```bash iostat [OPTIONS] [DEVICE] [INTERVAL [COUNT]] ``` | Option | Purpose | | ------ | ----------------------------------------- | | `-c` | Display CPU utilization | | `-d` | Display device utilization report | | `-h` | Display in human readable format | | `-m` | Display stats in megabytes per second | | `-N` | Display the registered device mapper name | | `-t` | Print the time for each report | | `-x` | Display extended statistics | | `-y` | Omit the first report | {% code overflow="wrap" %} ```bash [root@linuxmaster ~]# iostat Linux 3.10.0-1160.76.1.el7.x86_64 (linuxmaster) 09/15/2022 _x86_64_(1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 9.47 0.00 7.00 0.98 0.00 82.55 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 60.79 1802.02 23505.63 210728 2748748 [root@linuxmaster ~]# iostat -c Linux 3.10.0-1160.76.1.el7.x86_64 (linuxmaster) 09/15/2022 _x86_64_(1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 2.92 0.00 2.29 0.30 0.00 94.49 [root@linuxmaster ~]# iostat -c -y 1 4 Linux 3.10.0-1160.76.1.el7.x86_64 (linuxmaster) 09/15/2022 _x86_64_(1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 1.00 0.00 0.00 0.00 0.00 99.00 avg-cpu: %user %nice %system %iowait %steal %idle 0.00 0.00 0.00 0.00 0.00 100.00 avg-cpu: %user %nice %system %iowait %steal %idle 0.00 0.00 0.00 0.00 0.00 100.00 avg-cpu: %user %nice %system %iowait %steal %idle 0.00 0.00 0.00 0.00 0.00 100.00 ``` {% endcode %} * `sar`: Collect, report, or save system activity information. Provided by the sysstat command. sar creates a binary file for each day of the month with all the information collected (e.g., sa01), as well as a daily summary (e.g.,sar01). These files are overwritten the following month. The sysstat service must be started for sar to start collecting data and the duration of collection can be changed by modifying `/etc/cron.d/sysstat`. ```bash sar [OPTIONS] [INTERVAL [COUNT ]] ``` | Option | Purpose | | ------ | -------------------------------------------- | | `-B` | Report paging statistics | | `-b` | Report I/O and transfer rate statistics | | `-d` | Report activity for each block device | | `-f` | Extract records from a filename | | `-n` | Report network statistics based on a keyword | | `-o` | Save statistics to a binary file | | `-r` | Report memory utilization statistics | | `-u` | Report CPU utilization | {% code overflow="wrap" %} ```bash [root@linuxmaster ~]# systemctl status sysstat ● sysstat.service - Resets System Activity Logs Loaded: loaded (/usr/lib/systemd/system/sysstat.service; enabled; vendor preset: enabled) Active: active (exited) since Thu 2022-09-15 11:34:53 UTC; 4min 16s ago Process: 1524 ExecStart=/usr/lib64/sa/sa1 --boot (code=exited, status=0/SUCCESS) Main PID: 1524 (code=exited, status=0/SUCCESS) Sep 15 11:34:53 linuxmaster systemd[1]: Starting Resets System Activity Logs... Sep 15 11:34:53 linuxmaster systemd[1]: Started Resets System Activity Logs. [root@linuxmaster ~]# sar Linux 3.10.0-1160.76.1.el7.x86_64 (linuxmaster) 09/15/2022 _x86_64_ (1 CPU) 11:34:53 AM LINUX RESTART 11:40:01 AM CPU %user %nice %system %iowait %steal %idle 11:50:01 AM all 0.21 0.00 0.20 0.01 0.00 99.58 12:00:01 PM all 0.43 0.00 0.32 0.03 0.00 99.23 12:10:01 PM all 0.20 0.00 0.17 0.02 0.00 99.62 12:20:01 PM all 0.37 0.00 0.24 0.02 0.00 99.37 Average: all 0.30 0.00 0.23 0.02 0.00 99.45 [root@linuxmaster ~]# sar -y 1 5 Linux 3.10.0-1160.76.1.el7.x86_64 (linuxmaster) 09/15/2022 _x86_64_ (1 CPU) 11:39:27 AM TTY rcvin/s xmtin/s framerr/s prtyerr/s brk/s ovrun/s 11:39:28 AM 0 0.00 0.00 0.00 0.00 0.00 0.00 11:39:28 AM TTY rcvin/s xmtin/s framerr/s prtyerr/s brk/s ovrun/s 11:39:29 AM 0 0.00 0.00 0.00 0.00 0.00 0.00 11:39:29 AM TTY rcvin/s xmtin/s framerr/s prtyerr/s brk/s ovrun/s 11:39:30 AM 0 0.00 0.00 0.00 0.00 0.00 0.00 11:39:30 AM TTY rcvin/s xmtin/s framerr/s prtyerr/s brk/s ovrun/s 11:39:31 AM 0 0.00 0.00 0.00 0.00 0.00 0.00 11:39:31 AM TTY rcvin/s xmtin/s framerr/s prtyerr/s brk/s ovrun/s 11:39:32 AM 0 0.00 0.00 0.00 0.00 0.00 0.00 Average: TTY rcvin/s xmtin/s framerr/s prtyerr/s brk/s ovrun/s Average: 0 0.00 0.00 0.00 0.00 0.00 0.00 [root@linuxmaster ~]# sar -d Linux 3.10.0-1160.76.1.el7.x86_64 (linuxmaster) 09/15/2022 _x86_64_ (1 CPU) 11:34:53 AM LINUX RESTART 11:40:01 AM DEV tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await svctm %util 11:50:01 AM dev8-0 0.61 0.08 10.49 17.36 0.00 0.57 0.28 0.02 12:00:01 PM dev8-0 1.01 2.30 24.28 26.24 0.00 0.85 0.30 0.03 12:10:01 PM dev8-0 0.59 0.29 10.25 17.95 0.00 0.44 0.31 0.02 12:20:01 PM dev8-0 1.04 1.41 21.38 21.97 0.00 2.10 0.30 0.03 Average: dev8-0 0.81 1.02 16.60 21.71 0.00 1.12 0.30 0.02 ``` {% endcode %} ```bash [root@linuxmaster sa]# cat /etc/cron.d/sysstat # Run system activity accounting tool every 10 minutes */10 * * * * root /usr/lib64/sa/sa1 1 1 # 0 * * * * root /usr/lib64/sa/sa1 600 6 & # Generate a daily summary of process accounting at 23:53 53 23 * * * root /usr/lib64/sa/sa2 -A ``` * `free`: Display the amount of free and used memory in the system (default is Kb). The information displayed by free is pulled from the /proc/meminfo file. Swap is a substitute for physical memory that uses the hard disk. The /proc/sys/vm/swappiness file determines how aggressively a system will swap. ```bash free [OPTIONS] ``` | Option | Purpose | | ------ | ----------------------------------------------- | | `-m` | Display memory in megabytes | | `-g` | Display memory in gigabytes | | `-h` | Display output in human-readable format | | `-w` | Switch to wide mode | | `-s` | Continually display output in seconds specified | | `-c` | Set a count for the -s option | ```bash [root@linuxmaster ~]# free total used free shared buff/cache available Mem: 1832812 96900 1379484 8684 356428 1585340 Swap: 0 0 0 [root@linuxmaster ~]# free -h total used free shared buff/cache available Mem: 1.7G 94M 1.3G 8.5M 348M 1.5G Swap: 0B 0B 0B [root@linuxmaster sa]# free -h -s 1 -c 3 total used free shared buff/cache available Mem: 1.7G 96M 1.3G 8.5M 348M 1.5G Swap: 0B 0B 0B total used free shared buff/cache available Mem: 1.7G 96M 1.3G 8.5M 348M 1.5G Swap: 0B 0B 0B total used free shared buff/cache available Mem: 1.7G 96M 1.3G 8.5M 348M 1.5G Swap: 0B 0B 0B ``` * `vmstat`: Reports virtual memory statistics as well as statistics on paging and block I/O. By default, vmstat prints a summary of usage statistics since the last reboot. vmstat can run at an interval with a count or continuously. The first report in the interval is the summary report. ```bash vmstat [OPTIONS] [DELAY [COUNT]] ``` | Option | Purpose | | ------ | ------------------------------------ | | `-a` | Display active and inactive memory | | `-s` | Display a table of memory statistics | | `-d` | Report disk statistics | | `-D` | Report summary statistics on disks | | `-t` | Append a timestamp to each line | | `-w` | Wide output mode | ```bash [root@linuxmaster ~]# vmstat procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 2 0 0 1379508 13376 343080 0 0 735 467 132 200 4 3 93 0 0 [root@linuxmaster ~]# vmstat 1 4 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 2 0 0 1378676 13728 343292 0 0 226 146 54 82 1 1 98 0 0 0 0 0 1378676 13728 343292 0 0 0 0 17 28 0 0 100 0 0 0 0 0 1378676 13728 343292 0 0 0 0 17 29 0 0 100 0 0 0 0 0 1378676 13728 343292 0 0 0 0 11 21 0 0 100 0 0 [root@linuxmaster ~]# vmstat -d 1 4 disk- ------------reads------------ ------------writes----------- -----IO------ total merged sectors ms total merged sectors ms cur sec sr0 0 0 0 0 0 0 0 0 0 0 sda 5820 8 422073 3096 1989 2803 5547568 9038 0 2 sr0 0 0 0 0 0 0 0 0 0 0 sda 5820 8 422073 3096 1991 2806 5547608 9040 0 2 sr0 0 0 0 0 0 0 0 0 0 0 sda 5820 8 422073 3096 1991 2806 5547608 9040 0 2 sr0 0 0 0 0 0 0 0 0 0 0 sda 5820 8 422073 3096 2003 2808 5547720 9052 0 2 [root@linuxmaster ~]# vmstat -s 1832812 K total memory 99164 K used memory 268444 K active memory 110020 K inactive memory 1376568 K free memory 13768 K buffer memory 343312 K swap cache 0 K total swap 0 K used swap 0 K free swap 1239 non-nice user cpu ticks 0 nice user cpu ticks 986 system cpu ticks 96054 idle cpu ticks 125 IO-wait cpu ticks 0 IRQ cpu ticks 13 softirq cpu ticks 0 stolen cpu ticks 211036 pages paged in 136768 pages paged out 0 pages swapped in 0 pages swapped out 51272 interrupts 78430 CPU context switches 1663241496 boot time 1637 forks ``` ### Viewing Open Files and Running Processes * `lsof`: Lists open files on the system. By default, the command will display all open files belonging to all active processes. When multiple options are used, it will display open files that meet any of the criteria (ORing), but the -a option can be used to AND the selections (ANDing). ```bash lsof [OPTIONS] [NAMES] ``` | Option | Purpos | | ------ | ----------------------------------------------------------------- | | `-a` | Causes selections to be ANDed | | `-c` | List files based on command entered | | `-i` | List files based on a network connection | | `+d` | List files associated with a directory | | `+D` | List files associated with a directory (includes sub directories) | | `-p` | List files based on PID | | `-t` | Display terse output (PIDs only) | | `-u` | List files based on User | | `^` | Used to negate a selection entered | {% code overflow="wrap" %} ```bash [root@linuxmaster ~]# lsof | head COMMAND PID TID USER FD TYPE DEVICE SIZE/OFF NODE NAME systemd 1 root cwd DIR 8,1 4096 2 / systemd 1 root rtd DIR 8,1 4096 2 / systemd 1 root txt REG 8,1 1632960 12858 /usr/lib/systemd/systemd systemd 1 root mem REG 8,1 20064 5240 /usr/lib64/libuuid.so.1.3.0 systemd 1 root mem REG 8,1 265576 10126 /usr/lib64/libblkid.so.1.1.0 systemd 1 root mem REG 8,1 90160 5211 /usr/lib64/libz.so.1.2.7 systemd 1 root mem REG 8,1 157440 5229 /usr/lib64/liblzma.so.5.2.2 systemd 1 root mem REG 8,1 23968 5585 /usr/lib64/libcap-ng.so.0.0.0 systemd 1 root mem REG 8,1 19896 5553 /usr/lib64/libattr.so.1.1.0 [root@linuxmaster ~]# lsof -u ^root | head COMMAND PID TID USER FD TYPE DEVICE SIZE/OFF NODE NAME polkitd 540 polkitd cwd DIR 8,1 4096 2 / polkitd 540 polkitd rtd DIR 8,1 4096 2 / polkitd 540 polkitd txt REG 8,1 120432 13264 /usr/lib/polkit-1/polkitd polkitd 540 polkitd mem REG 8,1 61560 4728 /usr/lib64/libnss_files-2.17.so polkitd 540 polkitd mem REG 8,1 68192 5318 /usr/lib64/libbz2.so.1.0.6 polkitd 540 polkitd mem REG 8,1 99944 5540 /usr/lib64/libelf-0.176.so polkitd 540 polkitd mem REG 8,1 19896 5553 /usr/lib64/libattr.so.1.1.0 polkitd 540 polkitd mem REG 8,1 20064 5240 /usr/lib64/libuuid.so.1.3.0 polkitd 540 polkitd mem REG 8,1 265576 10126 /usr/lib64/libblkid.so.1.1.0 [root@linuxmaster ~]# lsof -u root -t 1 2 4 5 6 7 8 9 10 11 ... [root@linuxmaster ~]# lsof -u root -t | wc -l 70 [root@linuxmaster ~]# lsof -i COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME chronyd 546 chrony 5u IPv4 13335 0t0 UDP linuxmaster:323 chronyd 546 chrony 6u IPv6 13336 0t0 UDP linuxmaster:323 dhclient 643 root 6u IPv4 15146 0t0 UDP *:bootpc sshd 1118 root 3u IPv4 16844 0t0 TCP *:ssh (LISTEN) sshd 1118 root 4u IPv6 16846 0t0 TCP *:ssh (LISTEN) sshd 1145 root 3u IPv4 16984 0t0 TCP static.120.221.201.195.clients.your-server.de:ssh->88.232.191.134.dynamic.ttnet.com.tr:58976 (ESTABLISHED) sshd 2029 root 3u IPv4 31059 0t0 TCP static.120.221.201.195.clients.your-server.de:ssh->157.230.183.86:52592 (ESTABLISHED) sshd 2030 sshd 3u IPv4 31059 0t0 TCP static.120.221.201.195.clients.your-server.de:ssh->157.230.183.86:52592 (ESTABLISHED) [root@linuxmaster ~]# lsof -i tcp COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME sshd 1118 root 3u IPv4 16844 0t0 TCP *:ssh (LISTEN) sshd 1118 root 4u IPv6 16846 0t0 TCP *:ssh (LISTEN) sshd 1145 root 3u IPv4 16984 0t0 TCP static.120.221.201.195.clients.your-server.de:ssh->88.232.191.134.dynamic.ttnet.com.tr:58976 (ESTABLISHED) [root@linuxmaster ~]# lsof -c sshd | head COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME sshd 1118 root cwd DIR 8,1 4096 2 / sshd 1118 root rtd DIR 8,1 4096 2 / sshd 1118 root txt REG 8,1 852888 14974 /usr/sbin/sshd sshd 1118 root mem REG 8,1 61560 4728 /usr/lib64/libnss_files-2.17.so sshd 1118 root mem REG 8,1 68192 5318 /usr/lib64/libbz2.so.1.0.6 sshd 1118 root mem REG 8,1 99944 5540 /usr/lib64/libelf-0.176.so sshd 1118 root mem REG 8,1 19896 5553 /usr/lib64/libattr.so.1.1.0 sshd 1118 root mem REG 8,1 15688 6404 /usr/lib64/libkeyutils.so.1.5 sshd 1118 root mem REG 8,1 67104 9009 /usr/lib64/libkrb5support.so.0.1 [root@linuxmaster ~]# lsof +d /var/log COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME rsyslogd 1122 root 6w REG 8,1 73546 17793 /var/log/messages rsyslogd 1122 root 7w REG 8,1 111655 17794 /var/log/secure rsyslogd 1122 root 8w REG 8,1 1305 6991 /var/log/cron [root@linuxmaster ~]# lsof +D /var/log COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME auditd 514 root 5w REG 8,1 708911 6714 /var/log/audit/audit.log tuned 855 root 3w REG 8,1 1527 6992 /var/log/tuned/tuned.log rsyslogd 1122 root 6w REG 8,1 73546 17793 /var/log/messages rsyslogd 1122 root 7w REG 8,1 111655 17794 /var/log/secure rsyslogd 1122 root 8w REG 8,1 1305 6991 /var/log/cron [root@linuxmaster ~]# lsof -a -c rsyslogd +d /var/log COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME rsyslogd 1122 root 6w REG 8,1 73546 17793 /var/log/messages rsyslogd 1122 root 7w REG 8,1 113779 17794 /var/log/secure rsyslogd 1122 root 8w REG 8,1 1305 6991 /var/log/cron [root@linuxmaster ~]# lsof -c rsyslogd +d /var/log | head COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME rsyslogd 1122 root cwd DIR 8,1 4096 2 / rsyslogd 1122 root rtd DIR 8,1 4096 2 / rsyslogd 1122 root txt REG 8,1 664008 17789 /usr/sbin/rsyslogd rsyslogd 1122 root mem REG 0,20 8388608 8320 /run/log/journal/ffc3a14c22e24c419f4abca29738ab08/system.journal rsyslogd 1122 root mem REG 8,1 68192 5318 /usr/lib64/libbz2.so.1.0.6 rsyslogd 1122 root mem REG 8,1 99944 5540 /usr/lib64/libelf-0.176.so rsyslogd 1122 root mem REG 8,1 402384 5189 /usr/lib64/libpcre.so.1.2.0 rsyslogd 1122 root mem REG 8,1 19896 5553 /usr/lib64/libattr.so.1.1.0 rsyslogd 1122 root mem REG 8,1 338672 12539 /usr/lib64/libdw-0.176.so ``` {% endcode %} * `ps`: Report a snapshot of the current processes. By default, ps selects all process with the same effective user ID as the current user and the associated terminal. ```bash ps [OPTIONS] ``` `ps` accept several different kinds of options: * UNIX - May be grouped and must be preceded by a dash. * BSD - May be grouped but must not use a dash. * GNU long - Preceded by two dashes. | Option | Purpose | | ------ | ------------------------------ | | `-e` | Select all processes | | `-C` | Select by command name | | `-p` | Select by PID | | `-t` | Select by tty | | `-u` | Select by effective UID | | `-f` | Display in full-format listing | {% code overflow="wrap" %} ```bash [root@linuxmaster ~]# ps PID TTY TIME CMD 1332 pts/0 00:00:00 bash 1921 pts/0 00:00:00 ps [root@linuxmaster ~]# ps -ef | head UID PID PPID C STIME TTY TIME CMD root 1 0 0 11:31 ? 00:00:02 /usr/lib/systemd/systemd --switched-root --system --deserialize 21 root 2 0 0 11:31 ? 00:00:00 [kthreadd] root 4 2 0 11:31 ? 00:00:00 [kworker/0:0H] root 5 2 0 11:31 ? 00:00:00 [kworker/u2:0] root 6 2 0 11:31 ? 00:00:00 [ksoftirqd/0] root 7 2 0 11:31 ? 00:00:00 [migration/0] root 8 2 0 11:31 ? 00:00:00 [rcu_bh] root 9 2 0 11:31 ? 00:00:00 [rcu_sched] root 10 2 0 11:31 ? 00:00:00 [lru-add-drain] [root@linuxmaster ~]# ps -fC sshd UID PID PPID C STIME TTY TIME CMD root 1118 1 0 11:31 ? 00:00:00 /usr/sbin/sshd -D root 1145 1118 0 11:31 ? 00:00:00 sshd: root@pts/0 root 2065 1118 0 12:28 ? 00:00:00 sshd: [accepted] root 2087 1118 0 12:29 ? 00:00:00 sshd: unknown [priv] sshd 2088 2087 0 12:29 ? 00:00:00 sshd: unknown [net] [root@linuxmaster ~]# ps -fp 1 UID PID PPID C STIME TTY TIME CMD root 1 0 0 11:31 ? 00:00:02 /usr/lib/systemd/systemd --switched-root --system - ``` {% endcode %} * `pstree`: Display running processes as a visual tree. ```bash pstree [OPTIONS] ``` | Option | Purpose | | ------ | ------------------------------------- | | `-A` | Use ASCII characters to draw the tree | | `-G` | Use VT100 line drawing characters | | `-a` | Show command line arguments | | `-p` | Show PIDs | | `-n` | Sort by PID instead of name | | `-Z` | Show SELinux security contex | {% code overflow="wrap" %} ```bash [root@linuxmaster ~]# pstree systemd─┬─NetworkManager─┬─dhclient │ └─2*[{NetworkManager}] ├─2*[agetty] ├─anacron ├─auditd───{auditd} ├─chronyd ├─crond ├─dbus-daemon───{dbus-daemon} ├─lvmetad ├─polkitd───6*[{polkitd}] ├─qemu-ga ├─rsyslogd───2*[{rsyslogd}] ├─sshd───sshd───bash───pstree ├─systemd-journal ├─systemd-logind ├─systemd-udevd └─tuned───4*[{tuned}] [root@linuxmaster ~]# pstree -p systemd(1)─┬─NetworkManager(627)─┬─dhclient(643) │ ├─{NetworkManager}(628) │ └─{NetworkManager}(630) ├─agetty(1126) ├─agetty(1127) ├─anacron(1809) ├─auditd(514)───{auditd}(515) ├─chronyd(546) ├─crond(1125) ├─dbus-daemon(543)───{dbus-daemon}(549) ├─lvmetad(401) ├─polkitd(540)─┬─{polkitd}(548) │ ├─{polkitd}(550) │ ├─{polkitd}(553) │ ├─{polkitd}(554) │ ├─{polkitd}(555) │ └─{polkitd}(558) ├─qemu-ga(538) ├─rsyslogd(1122)─┬─{rsyslogd}(1132) │ └─{rsyslogd}(1136) ├─sshd(1118)───sshd(1145)───bash(1332)───pstree(10018) ├─systemd-journal(381) ├─systemd-logind(551) ├─systemd-udevd(417) └─tuned(855)─┬─{tuned}(1024) ├─{tuned}(1025) ├─{tuned}(1030) └─{tuned}(1033) [root@linuxmaster ~]# pstree -pa | head systemd,1 --switched-root --system --deserialize 21 |-NetworkManager,627 --no-daemon | |-dhclient,643 -d -q -sf /usr/libexec/nm-dhcp-helper -pf /var/run/dhclient-eth0.pid -lf... | |-{NetworkManager},628 | `-{NetworkManager},630 |-agetty,1126 --keep-baud 115200,38400,9600 ttyS0 vt220 |-agetty,1127 --noclear tty1 linux |-anacron,1809 -s |-auditd,514 | `-{auditd},515 ``` {% endcode %} * `top`: Display a dynamic, real-time view of processes running on the system. The program provides a limited interactive interface for process mainpulation, as well as a much more extensive interface for personal configuration. ```bash top [OPTIONS] ``` | Option | Purpose | | ------ | --------------------------------- | | `d` | Change output delay | | `h` | Show list of options (help) | | `H` | Show thread count | | `m` | Display visual output of memory | | `f` | Open field management window | | `R` | Sort from least to most | | `W` | Write configuration to a file | | `n` | Set number of processes displayed | | `k` | Kill a process | {% code overflow="wrap" %} ```bash [root@linuxmaster ~]# top top - 12:19:34 up 47 min, 1 user, load average: 0.00, 0.01, 0.05 Tasks: 71 total, 1 running, 70 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 1832812 total, 1370016 free, 98232 used, 364564 buff/cache KiB Swap: 0 total, 0 free, 0 used. 1582868 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1950 root 20 0 161968 2144 1548 R 0.3 0.1 0:00.02 top 1 root 20 0 128128 6776 4220 S 0.0 0.4 0:02.60 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd 4 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H 5 root 20 0 0 0 0 S 0.0 0.0 0:00.06 kworker/u2:0 6 root 20 0 0 0 0 S 0.0 0.0 0:00.07 ksoftirqd/0 7 root rt 0 0 0 0 S 0.0 0.0 0:00.00 migration/0 ... ``` {% endcode %} ```bash # load average: 0.47, 24.71, 35.31 # 1, 5 and 15 minutes ``` ### Measuring Network Usage and System Availability * `netstat`: Print information on network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. By default, netstat displays a list of open sockets. The netstat command is obsolete and has been replaced by ss. other replacements include: `ip route` for `netstat -r`, `ip -s link` for `netstat -i`, and `ip maddr` for `netstat -g.` ```bash netstat [OPTIONS] [DELAY] ``` | Option | Purpose | | ------- | ------------------------------------------------ | | `-r` | Display kernel routing table | | `-g` | Display multicast group information | | `-i` | Display a table for network interfaces | | `-s` | Display summary statistics for each protocol | | `-n` | Show numerical address (do not resolve hostname) | | `-c` | Display output continuously | | `-p` | Show PID and process name | | `-l` | Show only listening sockets | | `-t` | Display TCP connections | | `-u` | Display UDP connections | | `delay` | Set DELAY in seconds | {% code overflow="wrap" %} ```bash [root@linuxmaster ~]# netstat | head Active Internet connections (w/o servers) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 53 0 static.120.221.201.:ssh 157.230.183.86:47510 CLOSE_WAIT tcp 0 36 static.120.221.201.:ssh 88.232.191.134.dy:58976 ESTABLISHED Active UNIX domain sockets (w/o servers) Proto RefCnt Flags Type State I-Node Path unix 3 [ ] DGRAM 8213 /run/systemd/notify unix 2 [ ] DGRAM 8215 /run/systemd/cgroups-agent unix 2 [ ] DGRAM 13337 /var/run/chrony/chronyd.sock unix 5 [ ] DGRAM 8235 /run/systemd/journal/socket [root@linuxmaster ~]# netstat -n | head Active Internet connections (w/o servers) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 195.201.221.120:22 61.177.172.91:38436 ESTABLISHED tcp 0 36 195.201.221.120:22 88.232.191.134:58976 ESTABLISHED Active UNIX domain sockets (w/o servers) Proto RefCnt Flags Type State I-Node Path unix 3 [ ] DGRAM 8213 /run/systemd/notify unix 2 [ ] DGRAM 8215 /run/systemd/cgroups-agent unix 2 [ ] DGRAM 13337 /var/run/chrony/chronyd.sock unix 5 [ ] DGRAM 8235 /run/systemd/journal/socket [root@linuxmaster ~]# netstat -r Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface default gateway 0.0.0.0 UG 0 0 0 eth0 gateway 0.0.0.0 255.255.255.255 UH 0 0 0 eth0 static.120.221. 0.0.0.0 255.255.255.255 UH 0 0 0 eth0 [root@linuxmaster ~]# netstat -nl | head Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp6 0 0 :::22 :::* LISTEN udp 0 0 0.0.0.0:68 0.0.0.0:* udp 0 0 127.0.0.1:323 0.0.0.0:* udp6 0 0 ::1:323 :::* Active UNIX domain sockets (only servers) Proto RefCnt Flags Type State I-Node Path unix 2 [ ACC ] SEQPACKET LISTENING 11043 /run/udev/control [root@linuxmaster ~]# netstat -nlp | head Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1118/sshd tcp6 0 0 :::22 :::* LISTEN 1118/sshd udp 0 0 0.0.0.0:68 0.0.0.0:* 643/dhclient udp 0 0 127.0.0.1:323 0.0.0.0:* 546/chronyd udp6 0 0 ::1:323 :::* 546/chronyd Active UNIX domain sockets (only servers) Proto RefCnt Flags Type State I-Node PID/Program name Path unix 2 [ ACC ] SEQPACKET LISTENING 11043 1/systemd /run/udev/control root@linuxmaster ~]# netstat -tlnp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1118/sshd tcp6 0 0 :::22 :::* LISTEN 1118/sshd [root@linuxmaster ~]# netstat -ulnp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name udp 0 0 0.0.0.0:68 0.0.0.0:* 643/dhclient udp 0 0 127.0.0.1:323 0.0.0.0:* 546/chronyd udp6 0 0 ::1:323 :::* 546/chronyd [root@linuxmaster ~]# netstat -tulnp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1118/sshd tcp6 0 0 :::22 :::* LISTEN 1118/sshd udp 0 0 0.0.0.0:68 0.0.0.0:* 643/dhclient udp 0 0 127.0.0.1:323 0.0.0.0:* 546/chronyd udp6 0 0 ::1:323 :::* 546/chronyd ``` {% endcode %} * `w`: Display information about the users currently on the machine, and their processes. The header shows the current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes. The following entries are displayed for each user: login name, the tty name, the remote host, login time, idle time, JCPU, PCPU, and the command line of their current process. ```bash w [OPTIONS] USER ``` | Option | Purpose | | ------ | ------------------------------------------ | | `-h` | Don't print the header | | `-s` | Use short format | | `-i` | Display IP addresses rather than hostnames | | `user` | Display information for USER specified | ```bash [root@linuxmaster ~]# w 12:39:35 up 1:07, 1 user, load average: 0.00, 0.01, 0.05 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root pts/0 88.232.191.134 11:31 7.00s 0.32s 0.00s w [root@linuxmaster ~]# w -h root pts/0 88.232.191.134 11:31 4.00s 0.37s 0.01s w -h [root@linuxmaster ~]# w -s 12:51:12 up 1:19, 1 user, load average: 0.00, 0.01, 0.05 USER TTY FROM IDLE WHAT root pts/0 88.232.191.134 0.00s w -s ``` * `uptime`: Display how long the system has been running. By default, displays the same information found in the header of the `w` command. Shows the current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes. Both `w` and `uptime` get their information from `/var/run/utmp`. ```bash uptime [OPTIONS] ``` | Option | Purpose | | ------ | -------------------------------------------- | | `-p` | Show uptime in pretty format | | `-h` | Display help text | | `-s` | Display uptime in yyyy-mm-dd HH:MM:SS format | | `-V` | Display version information | ```bash [root@linuxmaster ~]# uptime 12:39:56 up 1:08, 1 user, load average: 0.00, 0.01, 0.05 [root@linuxmaster ~]# uptime -p up 1 hour, 20 minutes [root@linuxmaster ~]# uptime -s 2022-09-15 11:31:36 ``` ## 200.2 Predict Future Resource Needs (weight: 2) {% hint style="success" %} Candidates should be able to monitor resource usage to predict future resource needs.\ \\ **Key Knowledge Areas:** * Use monitoring and measurement tools to monitor IT infrastructure usage. * Predict capacity break point of a configuration. * Observe growth rate of capacity usage. * Graph the trend of capacity usage. * Awareness of monitoring solutions such as Icinga2, Nagios, collectd, MRTG and Cacti **The following is a partial list of the used files, terms and utilities:** * diagnose * predict growth * resource exhaustion {% endhint %} ### Monitoring Solutions #### Nagios Nagios is an industry-standard IT monitoring solution. * Provides complete monitoring for Linux operating systems and distributions * Provides two options for monitoring hosts * Using dedicated Nagios agents * Using SNMP for "agentless" monitoring * Provides advanced graphs and visual aids * Provides automated and integrated capacity planning #### Icinga2 Icinga2 is a monitoring solution that reports on various usage statistics by using a primary node, satellites, and agents. * Monitors network resources * Notifies users of outages * Generates performance data * Runs on Linux/Unix and Windows #### MRTG The Multi Router Traffic Grapher is a tool for monitoring routers and other network devices. * Monitors SNMP network devices * Monitors traffic load on network links * Generates HTML pages containing PNG images of live data * Implements a data consolidation algorithm * Provides built-in hooks for using RRDTool #### Cacti A network graphing solution designed to work with RRDTool. * Provides a complete frontend to RRDTool * Uses a MySQL database to store data * Provides a built-in user-based management system * Provides graphs for displaying data * Allows data sources to be defined for data collection #### Collectd Collectd is a service daemon that collects system and applicatkin performance metrics periodically and provides mechanisms to store the values in a variety of ways (e.g. RRD files). * Gathers metrics from various sources * Stores metrics gathered or makes them available over the network * Provides information for performance analysis and capacity planning * Provides over 100 plugins for monitoring and integration with other solutions Installing and Configuration Collectd {% code overflow="wrap" %} ```bash root@linuxmaster:~# apt install collectd apache2 librrd-perl libconfig-general-perl libhtml-parser-perl libregexp-common-perl libcgi-session-perl root@linuxmaster:~# systemctl restart collectd root@linuxmaster:~# cp -r /usr/share/doc/collectd/examples/collection3/ /var/www/html root@linuxmaster:~# vim /etc/apache2/apache2.conf ## Add the following: AllowOverride None Options +ExectCGI AddHandler cgi-script .cgi .pl Require all granted root@linuxmaster:~# ln -s /etc/apache2/mod-available/cgi.load /etc/apache2/mods-enabled/ root@linuxmaster:~# systemctl restart apache2 ``` {% endcode %} ## Commands and Notes * `iostat`: Report on CPU statistics and input/output statistics for devices and partitions. * `sar`: Collect, report, or save system activity information. * sar creates a binary file for each day of the month with all the information collected (e.g., `sa01`), as well as a daily summary (e.g.,`sar01`). These files are overwritten the following month. The sysstat service must be started for sar to start collecting data and the duration of collection can be changed by modifying `/etc/cron.d/sysstat`. * `free`: Display the amount of free and used memory in the system. * `vmstat`: Reports virtual memory statistics as well as statistics on paging and block I/O. * `lsof`: Lists open files on the system. * `ps`: Report a snapshot of the current processes. * `pstree`: Display running processes as a visual tree. * `top`: Display a dynamic, real-time view of processes running on the system. * `netstat`: Print information on network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. * `w`: Display information about the users currently on the machine, and their processes. * `uptime`: Display how long the system has been running. * **Nagios** using SNMP for "agentless" monitoring. * **Icinga2** originally created as a fork of Nagios. * **MRTG** provides built-in hooks for using RRDTool. * **Cacti** a network graphing solution designed to work with RRDTool. * **Collectd** is a service daemon that collects system and applicatkin performance metrics periodically and provides mechanisms to store the values in a variety of ways (e.g. RRD files). ## Sample Questions **1.** Which of the following provides a complete frontend for RRDTool? * [ ] MRTG * [x] Cacti * [ ] Collectd * [ ] Nagios **2.** What command displays a dynamic view of processes running on the system? * [ ] lsof * [x] top * [ ] pstree * [ ] ps **3.** Which of the following was originally created as a fork of Nagios? * [ ] Collectd * [ ] MRTG * [ ] Cacti * [x] Icinga2 **4.** What file is used to change the duration of collection for sar? * [ ] /var/log/sa * [ ] /etc/sar.conf * [x] /etc/cron.d/sysstat * [ ] /etc/cron.d/sar **5.** What option for lsof lists open files based on network connections? * [ ] -c * [ ] -u * [x] -i * [ ] -p **6.** What commands show how long the system has been running? * [x] w * [ ] date * [x] uptime * [ ] stat **7.** What option for netstat displays the kernel routing table? * [ ] -l * [ ] -n * [ ] -i * [x] -r **8.** Which of the following are aspects of capacity planning? * [x] Collecting long term resource usage data * [x] Observing trends in resource usage * [ ] Implementing competitive salaries based on what the market will bear * [x] Consdiering business Initiatives **9.** What option only generates the device report with the iostat command? * [ ] -c * [ ] -y * [ ] -x * [x] -d **10.** What kinds of options are accepted by the `ps` command? (choose all that apply) * [ ] LSB * [x] UNIX * [x] GNU long * [x] BSD **11.** Which command reports information on memory usage, paging and block input/output? * [ ] free * [ ] memshow * [ ] lsof * [ ] pidof * [x] vmstat **12.** Which program lists information about files and network connections opened by processes? (Specify ONLY the command without any path or parameters.) **Answer:** lsof **13.** Which of the following commands by default provides the PIDs of the processes sorted by which are using the most CPU cycles on the Linux system? * [x] top * [ ] uptime * [ ] ps aux * [ ] vmstat * [ ] freemem **14.** In the following output of the command uptime, the load averages represent the system load averages for what time frames? ```bash 12:10:05 up 18 days, 19:00, 2 users, load average: 0.47, 24.71, 35.31 ``` * [x] 1, 5 and 15 minutes * [ ] 1, 15 and 30 minutes * [ ] 5, 20 and 25 seconds * [ ] 15, 30 and 60 minutes * [ ] 15, 45 and 90 seconds **15.** In order to gather performance data with `sar` over a longer period of time, which command should be run periodically from cron? * [x] sa1 * [ ] sarmon * [ ] sarec * [ ] sadf * [ ] sarcron **16.** In the output of `sar –b`, what does tps stand for? * [ ] Terrabyte per second * [ ] Traffic per second * [x] Transfers per second * [ ] Total data per second * [ ] Terrabit per second **17.** Which of the following monitoring commands allow you to view system memory information? (Choose all that apply.) * [x] free * [ ] mpstat * [x] top * [ ] mtr * [x] vmstat **18.** Which of the following will show CPU usage information 20 times in 2-second intervals? * [ ] uptime 20 2 * [ ] uptime 2 20 * [ ] sar 20 2 * [x] sar 2 20 * [ ] None of the above **19.** Which of the following are considered to be system resource-monitoring solutions? (Choose all that apply) * [x] collectd * [ ] Duplicity * [x] MRTG * [x] Nagios * [ ] All of the above **20.** Which of the following are true about Linux system memory? (Choose all that apply) * [ ] Memory is divided into sheets. * [x] Memory for an idle process can be swapped out to swap space. * [x] Swap can also be called virtual memory. * [ ] Swapping is the memory management scheme, where idle processes swap memory. * [ ] Memory-swapping statistics can be viewed using the psmap utility. **Answer:** B, C. Memory for idle processes can be swapped out from RAM to a special partition called swap space, swap, or virtual memory. Therefore, options B and C are correct. Memory is divided up into chunks called pages (option A), not sheets. Swapping is the memory management technique where idle processes’ memory is swapped out to swap. The processes do not trade memory (option D). Finally, the psmap tool is primarily for mapping processes (option E). The best tools for viewing memory statistics are tools like `free`, `sar`, and `vmstat`. **21.** In the following output from top, which processes contribute to the percentage of time that the CPU spends in the state of wa? ```bash Tasks: 193 total, 1 running, 190 sleeping, 2 stopped, 0 zombie Cpu(s): 0.5%us, 0.3%sy, 0.0%ni, 98.2%id, 1.0%wa, 0.0%hi, 0.0%si, 0.0%st ``` * [ ] Processes waiting for user interaction. * [ ] Processes that were already closed and are waiting to be launched again. * [ ] Processes that have not been scheduled yet because they haven't been fully loaded into RAM or are in swap. * [x] Processes waiting for IO operations to complete. **22.** In this example output, which descriptions match the purpose of the free, buff and cache columns? (Choose THREE correct answers.) ```bash # vmstat 1 100 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 282120 134108 5797012 0 0 0 2 0 0 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 359 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1117 577 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 366 0 0 100 0 ``` * [ ] Used swap space * [ ] RAM available for filesystem buffers * [x] Available free RAM * [x] RAM used for buffers * [x] RAM used for filesystem cache **23.** When is historical data of resource usage important? (Select THREE correct answers.) * [x] Predicting when resources will need to be increased. * [ ] Selecting a computer vendor. * [ ] Identifying processes killed during out of memory occurrences. * [x] Diagnosing capacity problems. * [x] Troubleshooting a software problem. **24.** In capacity planning exercises, which tools assist in listing and identifying processes of interest? (Choose TWO correct answers.) * [ ] acpid * [x] lsof * [x] pstree * [ ] telinit **25.** In the below example output, which columns detail the percent of time the CPU spent running non-kernel code and the percent of time the CPU spent running kernel code? (Choose TWO correct answers.) ```bash # vmstat 1 100 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 282120 134108 5797012 0 0 0 2 0 0 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 359 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1117 577 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 366 0 0 100 0 ``` * [ ] id * [x] us * [ ] wa * [x] sy **26.** In the following output, what percentage of time was the CPU waiting for pending I/O? ```bash # vmstat 1 100 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 282120 134108 5797012 0 0 0 2 0 0 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 359 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1117 577 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 366 0 0 100 0 ``` * [x] 0 * [ ] 100 * [ ] 35.9 * [ ] 57.7 * [ ] 36.6 **27.** Which of the following tools are used to measure memory usage? (Choose THREE correct answers.) * [ ] mpstat * [ ] pstree * [x] sar * [x] top * [x] vmstat **28.** Which of the following is a side effect of extensive usage of swap space? * [ ] The root filesystem may become full because swap space is always located on the system root partition. * [x] The overall system performance may degrade because of heavy hard disk use and memory reorganization. * [ ] Since processes always exist completely in either RAM or swap, regular RAM may become unused if the kernel does not move processes back from the swap space to memory. * [ ] The memory may become fragmented and slow down the access to memory pages. However, this can be kept to a minimum by the regular use of memfrag -d. * [ ] Applications need to restart because their virtual memory addresses change to reflect memory relocation to the swap address area. **29.** Which of the following commands will provide the PIDs of the processes sorted by which are using the most CPU cycles on the Linux system? * [x] top * [ ] uptime * [ ] ps aux * [ ] vmstat * [ ] freemem **30.** Which command will report information on memory usage, paging and block input/output? * [x] vmstat * [ ] free * [ ] memshow * [ ] ps * [ ] top **31.** Using the iostat command you want to display more detailed statistics (Extended), but you want the output of this command to be printed on the screen 5 times between 2-second update intervals. Which of the following is correct to accomplish this task? * [ ] iostat -v 5 2 * [ ] iostat -x 5 2 * [x] iostat -x 2 5 * [ ] iostat -v 2 5 **32.** Which of the commands below will return virtual memory statistics information about processes, memory, pagination, block IO, trap and CPU usage? * [x] vmstat * [ ] sar * [ ] pstree * [ ] iostat **33.** Which of the commands below is used to monitor the load of system input / output (I/O) devices. Where is this done by observing the devices are active in relation to their average transfer rates? * [ ] sar * [x] iostat * [ ] vmstat * [ ] pstree **34.** Which of the commands below collects, reports, or saves system activity information? * [x] sar * [ ] iostat * [ ] vmstat * [ ] pstree **35.** Which of the iostat command options can be used to display device statistics information (disks and partitions)? * [ ] iostat -x * [x] iostat -p * [ ] iostat -l * [ ] iostat -v **36.** Which of the iostat options can be used to display a CPU usage report? * [ ] iostat -b * [ ] iostat -x * [ ] iostat -d * [x] iostat -c **37.** Which of the iostat command options can be used to display a device usage report (Disks)? * [ ] iostat -b * [ ] iostat -x * [x] iostat -d * [ ] iostat -c **38.** Which command below displays information about the users currently connected to the machine, their processes and the same statistics as provided by the uptime command? * [ ] top * [x] w * [ ] free * [ ] whoami **39.** When outputting the vmstat command, in the procs field, what do the columns r and b mean? (Select 2 responses). * [ ] The number of executable processes (running and waiting for execution time). * [ ] Shows the percentage of time spent running non-kernel code. * [ ] The number of processes in uninterrupted sleep. * [ ] Show the percentage of time stolen from a virtual machine. **40.** Which of the columns below is related to the system field in the output of the vmstat command that shows the number of contexts per second, including the clock? * [x] cs * [ ] sy * [ ] in * [ ] wa * [ ] us **41.** Which of the columns below is related to the system field in the output of the vmstat command that shows the number of interrupts per second, including the clock? * [ ] cs * [ ] sy * [x] in * [ ] wa * [ ] us **42.** Which of the alternatives below are columns related to the swap field presented in the output of the vmstat command? (Select 2 responses). * [x] si * [ ] bi * [x] so * [ ] bo * [ ] id **43.** Which of the alternatives below are columns related to the io field presented in the output of the vmstat command? (Select 2 responses). * [ ] si * [x] bi * [ ] so * [x] bo * [ ] id **44.** Which of the following, using the vmstat command, will display event counter statistics? * [ ] vmstat -a * [ ] vmstat -d * [x] vmstat -s * [ ] vmstat -p * [ ] vmstat -D **45.** Which of the following, using the vmstat command, will display disk statistics? * [ ] vmstat -a * [x] vmstat -d * [ ] vmstat -s * [ ] vmstat -p * [ ] vmstat -D **46.** Which of the following, using the vmstat command, will display a summary of disk statistics? * [ ] vmstat -a * [ ] vmstat -d * [ ] vmstat -s * [ ] vmstat -p * [x] vmstat -D **47.** Which of the following, using the vmstat command, will display statistics for a specific partition? * [ ] vmstat -a * [ ] vmstat -d * [ ] vmstat -s * [x] vmstat -p * [ ] vmstat -D **48.** Which of the free command options will update the command output every 2 seconds for 5 times on the screen? (Select 2 responses). * [x] free -s 2 -c 5 * [x] free -s 2 --count 5 * [ ] free -s 2 5 * [ ] free -s 2 -r 5 **49.** Which of the free command options will update the command output on the screen every 2 seconds? * [ ] free -n 2 * [ ] free -t 2 * [x] free -s 2 * [ ] N.D.A **50.** Which of the alternatives below will list detailed memory statistics, showing the total RAM + SWAP memory, printing the result in the output in a more readable (- human) form for the user? * [ ] free -vht * [x] free -lth * [ ] free -ghl * [ ] free -x **51.** Which option in the sar command displays paging statistics? * [x] -B * [ ] -b * [ ] -d * [ ] -p * [ ] -r **52.** Which option in the sar command displays a memory usage statistics report? * [ ] -m * [ ] -b * [ ] -d * [ ] -R * [x] -r **53.** Which option of the sar command will report the queue size and load averages? * [ ] -S * [x] -q * [ ] -w * [ ] -y * [ ] -d **54.** Which option of the sar command will report an I/O transfer rate report? * [ ] -S * [ ] -q * [x] -b * [ ] -y * [ ] -d **55.** Which option of the sar command will report swap statistics? (Select 2 responses). * [x] -S * [ ] -q * [x] -W * [ ] -y * [ ] -d **56.** Which option of the sar command will report the activity of each block device? * [ ] -S * [ ] -q * [ ] -b * [ ] -y * [x] -d **57.** Which option in the sar command will report the activity of TTY (Remote Terminals) devices? * [ ] -S * [ ] -q * [ ] -b * [x] -y * [ ] -d **58.** Which of the commands below can be used to view the PID of a program that we have just started? (Select 2 responses). * [ ] iostat * [x] ps * [ ] vmstat * [x] top **59.** What is the result of the `ps ef` command? * [ ] List user processes running as a tree * [ ] List stopped processes. * [x] List all processes running as a tree. * [ ] List all system processes running as a tree. **60.** Which of the commands below will return a list of processes that are running on the current terminal? * [ ] top * [x] ps * [ ] vmstat * [ ] iostat **61.** Which command will list all processes, displaying the names of the users who started them? * [ ] ps a * [ ] ps ag * [x] ps aux * [ ] ps ac **62.** Which command displays details about the processes that are running in real time on the server? * [ ] ps * [x] top * [ ] vmstat * [ ] iostat **63.** Which of the options ("Internal option of the top command") below can be used to change the priority of a process already running? * [ ] -t * [ ] -d * [ ] -b * [x] -r * [ ] -k **64.** Which of the following will set the update time to 2 seconds on standard output using the top command? * [ ] top -n 2 * [x] top -d 2 * [ ] top -i 2 * [ ] N.D.A **65.** Which "top" command will ignore idle processes? * [ ] top -b * [x] top -i * [ ] top -d * [ ] N.D.A **66.** Which command will update the top command's standard output 4 times and then exit the program? * [ ] top -d 4 * [ ] top -i 4 * [x] top -n 4 * [ ] N.D.A **67.** Which top command will only list the processes of the user root? * [ ] top -L root * [x] top -u root * [ ] top -l root * [ ] N.D.A