204.1 Configuring RAID (weight: 3)
Candidates should be able to configure and implement software RAID. This objective includes using and configuring RAID 0, 1 and 5.
Key Knowledge Areas:
Software RAID configuration files and utilities
The following is a partial list of the used files, terms and utilities:
Undrestanding RAID and RAID Levels
RAID stands for Redundant Array of Independent Disks and is a storage solution that is used to organize or combine a group of disks into one or more logical units .
RAID 0: Striping
RAID 1: Mirroring
RAID 5: Block-Level Stripping with Distributed Parity
Files and Utilities for Interacting with RAID
mdadm.conf: Main configuration file for the management of software raid with the mdadm utility
/proc/mdstat: Display a snapshot of the kernel's RAID/md stat.
0xFD partition type: Type ID number that signifies a RAID partition.
mdadm: A utility for creating, managing, and monitoring RAID devices using the md driver in Linux.
Copy mdadm [mode] < raiddevice > [options] < component-devices > Option Description Specify number of devices
Specify number of spare devices
Print details of one or more md devices
Add one or more devices to the array
Mark listed devices as faulty
Scan the map file for arrays
Creating a Software RAID
Copy [root@linuxmaster ~ ]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 38.2G 0 disk
└─sda1 8:1 0 38.2G 0 part /
sdb 8:16 0 10G 0 disk
├─sdb1 8:17 0 1G 0 part
├─sdb2 8:18 0 1G 0 part
└─sdb3 8:19 0 1G 0 part
sdc 8:32 0 10G 0 disk
├─sdc1 8:33 0 1G 0 part
└─sdc2 8:34 0 1G 0 part
sr0 11:0 1 1024M 0 rom
[root@linuxmaster ~ ]# mdadm -C /dev/md0 -l raid5 -n 3 /dev/sdb1 /dev/sdb2 /dev/sdb3 -x 2 /dev/sdc1 /dev/sdc2
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
[root@linuxmaster ~ ]# ll /dev/md0
brw-rw----. 1 root disk 9, 0 Sep 10 10:34 /dev/md0
[root@linuxmaster ~ ]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Sep 10 10:34:50 2022
Raid Level : raid5
Array Size : 2093056 (2044.00 MiB 2143.29 MB )
Used Dev Size : 1046528 (1022.00 MiB 1071.64 MB )
Raid Devices : 3
Total Devices : 5
Persistence : Superblock is persistent
Update Time : Sat Sep 10 10:35:29 2022
State : clean
Active Devices : 3
Working Devices : 5
Failed Devices : 0
Spare Devices : 2
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : centos-2gb-hel1-1:0
UUID : 04d4ef0e:16a91fb8:f82fec5f:59832a86
Events : 18
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 18 1 active sync /dev/sdb2
5 8 19 2 active sync /dev/sdb3
3 8 33 - spare /dev/sdc1
4 8 34 - spare /dev/sdc2
[root@linuxmaster ~ ]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb3[5] sdc2[4] ( S ) sdc1[3] ( S ) sdb2[1] sdb1[0]
2093056 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: < non e >
[root@linuxmaster ~ ]# mdadm -D -s -v
ARRAY /dev/md0 level=raid5 num-devices=3 metadata=1.2 spares=2 name=linuxmaster:0 UUID=04d4ef0e:16a91fb8:f82fec5f:59832a86
devices = /dev/sdb1,/dev/sdb2,/dev/sdb3,/dev/sdc1,/dev/sdc2
[root@linuxmaster ~ ]# mdadm -D -s -v > /etc/mdadm.conf
[root@linuxmaster ~ ]# cat /etc/mdadm.conf
ARRAY /dev/md0 level=raid5 num-devices=3 metadata=1.2 spares=2 name=linuxmaster:0 UUID=04d4ef0e:16a91fb8:f82fec5f:59832a86
devices = /dev/sdb1,/dev/sdb2,/dev/sdb3,/dev/sdc1,/dev/sdc2 Failing Active RAID Devices
Copy [root@linuxmaster ~ ]# mkfs.ext4 /dev/md0
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size= 4096 (log=2)
Fragment size= 4096 (log=2)
Stride = 128 blocks, Stripe width= 256 blocks
130816 inodes, 523264 blocks
26163 blocks (5.00%) reserved for the super user
First data block= 0
Maximum filesystem blocks= 536870912
16 block groups
32768 blocks per group, 32768 fragments per group
8176 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks ): done
Writing superblocks and filesystem accounting information: done
[root@linuxmaster ~ ]# mkdir /mnt/raid
[root@linuxmaster ~ ]# mount -t ext4 /dev/md0 /mnt/raid/
[root@linuxmaster ~ ]# touch /mnt/raid/test{ 1..5}
[root@linuxmaster ~ ]# ll /mnt/raid/
total 16
drwx------. 2 root root 16384 Sep 10 11:12 lost+found
-rw-r--r--. 1 root root 0 Sep 10 11:13 test1
-rw-r--r--. 1 root root 0 Sep 10 11:13 test2
-rw-r--r--. 1 root root 0 Sep 10 11:13 test3
-rw-r--r--. 1 root root 0 Sep 10 11:13 test4
-rw-r--r--. 1 root root 0 Sep 10 11:13 test5
[root@linuxmaster ~ ]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 871M 0 871M 0% /dev
tmpfs 895M 0 895M 0% /dev/shm
tmpfs 895M 8.7M 887M 1% /run
tmpfs 895M 0 895M 0% /sys/fs/cgroup
/dev/sda1 38G 1.1G 35G 3% /
tmpfs 179M 0 179M 0% /run/user/0
/dev/md0 2.0G 6.0M 1.9G 1% /mnt/raid
[root@linuxmaster ~ ]# mdadm -f /dev/md0 /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md0
[root@linuxmaster ~ ]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Sep 10 10:34:50 2022
Raid Level : raid5
Array Size : 2093056 (2044.00 MiB 2143.29 MB )
Used Dev Size : 1046528 (1022.00 MiB 1071.64 MB )
Raid Devices : 3
Total Devices : 5
Persistence : Superblock is persistent
Update Time : Sat Sep 10 11:14:30 2022
State : clean, degraded, recovering
Active Devices : 2
Working Devices : 4
Failed Devices : 1
Spare Devices : 2
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Rebuild Status : 30% complete
Name : centos-2gb-hel1-1:0
UUID : 04d4ef0e:16a91fb8:f82fec5f:59832a86
Events : 24
Number Major Minor RaidDevice State
4 8 34 0 spare rebuilding /dev/sdc2
1 8 18 1 active sync /dev/sdb2
5 8 19 2 active sync /dev/sdb3
0 8 17 - faulty /dev/sdb1
3 8 33 - spare /dev/sdc1
[root@linuxmaster ~ ]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb3[5] sdc2[4] sdc1[3] ( S ) sdb2[1] sdb1[0] ( F )
2093056 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [_UU]
[ ==============> ......] recovery = 73.2% (766720/1046528) finish = 0.2min speed = 19605K/sec
unused devices: < non e >
[root@linuxmaster ~ ]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Sep 10 10:34:50 2022
Raid Level : raid5
Array Size : 2093056 (2044.00 MiB 2143.29 MB )
Used Dev Size : 1046528 (1022.00 MiB 1071.64 MB )
Raid Devices : 3
Total Devices : 5
Persistence : Superblock is persistent
Update Time : Sat Sep 10 11:15:10 2022
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 1
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : centos-2gb-hel1-1:0
UUID : 04d4ef0e:16a91fb8:f82fec5f:59832a86
Events : 37
Number Major Minor RaidDevice State
4 8 34 0 active sync /dev/sdc2
1 8 18 1 active sync /dev/sdb2
5 8 19 2 active sync /dev/sdb3
0 8 17 - faulty /dev/sdb1
3 8 33 - spare /dev/sdc1
[root@linuxmaster ~ ]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb3[5] sdc2[4] sdc1[3] ( S ) sdb2[1] sdb1[0] ( F )
2093056 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: < non e >
[root@linuxmaster ~ ]# ll /mnt/raid/
total 16
drwx------. 2 root root 16384 Sep 10 11:12 lost+found
-rw-r--r--. 1 root root 0 Sep 10 11:13 test1
-rw-r--r--. 1 root root 0 Sep 10 11:13 test2
-rw-r--r--. 1 root root 0 Sep 10 11:13 test3
-rw-r--r--. 1 root root 0 Sep 10 11:13 test4
-rw-r--r--. 1 root root 0 Sep 10 11:13 test5
[root@linuxmaster ~ ]# mdadm -r /dev/sdb1
mdadm: /dev/sdb1 does not appear to be an md device
[root@linuxmaster ~ ]# mdadm -r /dev/sdc2
mdadm: /dev/sdc2 does not appear to be an md device
[root@linuxmaster ~ ]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Sep 10 10:34:50 2022
Raid Level : raid5
Array Size : 2093056 (2044.00 MiB 2143.29 MB )
Used Dev Size : 1046528 (1022.00 MiB 1071.64 MB )
Raid Devices : 3
Total Devices : 5
Persistence : Superblock is persistent
Update Time : Sat Sep 10 11:31:18 2022
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 2
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : centos-2gb-hel1-1:0
UUID : 04d4ef0e:16a91fb8:f82fec5f:59832a86
Events : 56
Number Major Minor RaidDevice State
3 8 33 0 active sync /dev/sdc1
1 8 18 1 active sync /dev/sdb2
5 8 19 2 active sync /dev/sdb3
0 8 17 - faulty /dev/sdb1
4 8 34 - faulty /dev/sdc2 Adding Devices to an Existing RAID
Copy [root@linuxmaster ~ ]# mdadm -a /dev/md0 /dev/sdd1 /dev/sdd2
mdadm: added /dev/sdd1
mdadm: added /dev/sdd2
[root@linuxmaster ~ ]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdd2[7] ( S ) sdd1[6] ( S ) sdb3[5] sdc2[4] ( F ) sdc1[3] sdb2[1] sdb1[0] ( F )
2093056 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: < non e >
[root@linuxmaster ~ ]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Sep 10 10:34:50 2022
Raid Level : raid5
Array Size : 2093056 (2044.00 MiB 2143.29 MB )
Used Dev Size : 1046528 (1022.00 MiB 1071.64 MB )
Raid Devices : 3
Total Devices : 7
Persistence : Superblock is persistent
Update Time : Sat Sep 10 11:35:36 2022
State : clean
Active Devices : 3
Working Devices : 5
Failed Devices : 2
Spare Devices : 2
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : centos-2gb-hel1-1:0
UUID : 04d4ef0e:16a91fb8:f82fec5f:59832a86
Events : 58
Number Major Minor RaidDevice State
3 8 33 0 active sync /dev/sdc1
1 8 18 1 active sync /dev/sdb2
5 8 19 2 active sync /dev/sdb3
0 8 17 - faulty /dev/sdb1
4 8 34 - faulty /dev/sdc2
6 8 49 - spare /dev/sdd1
7 8 50 - spare /dev/sdd2 Updating the mdadm.conf File
Copy [root@linuxmaster ~ ]# mdadm -D -s -v > /etc/mdadm.conf
[root@linuxmaster ~ ]# cat /etc/mdadm.conf
ARRAY /dev/md0 level=raid5 num-devices=3 metadata=1.2 spares=2 name=linuxmaster:0 UUID=04d4ef0e:16a91fb8:f82fec5f:59832a86
devices = /dev/sdb1,/dev/sdb2,/dev/sdb3,/dev/sdc1,/dev/sdc2,/dev/sdd1,/dev/sdd2 204.2 Adjusting Storage Device Access (weight: 2)
Candidates should be able to configure kernel options to support various drives. This objective includes software tools to view & modify hard disk settings including iSCSI devices.
Key Knowledge Areas:
Tools and utilities to configure DMA for IDE devices including ATAPI and SATA
Tools and utilities to configure Solid State Drives including AHCI and NVMe
Tools and utilities to manipulate or analyse system resources (e.g. interrupts)
Awareness of sdparm command and its uses
Tools and utilities for iSCSI
Awareness of SAN, including relevant protocols (AoE, FCoE)
The following is a partial list of the used files, terms and utilities:
/dev/hd*, /dev/sd*, /dev/nvme*
iscsiadm, scsi_id, iscsid and iscsid.conf
Direct Memory Access (DMA) and Interrupts Handling
Direct Memory Access allows hardware devices (e.g. disk drivers, network cards, sound cards, etc.) to effectively bypass the CPU and send or recive data directly from the main system memory rather than taking up large quantities of proccessing time. This process is managed by a DMA controller (DMAC).
Copy [root@linuxmaster ~ ]# cat /proc/interrupts
CPU0 CPU1
0: 178 0 IO-APIC-edge timer
1: 10 0 IO-APIC-edge i8042
4: 2382 0 IO-APIC-edge serial
8: 1 0 IO-APIC-edge rtc0
9: 0 0 IO-APIC-fasteoi acpi
12: 15 0 IO-APIC-edge i8042
16: 0 0 IO-APIC-fasteoi i801_smbus
22: 9 0 IO-APIC-fasteoi virtio3, virtio4
24: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
25: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
26: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
27: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
28: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
29: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
30: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
31: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
32: 1 0 PCI-MSI-edge aerdrv, PCIe PME, pciehp
33: 25 0 PCI-MSI-edge xhci_hcd
34: 0 0 PCI-MSI-edge xhci_hcd A hardware interrupt or interrupt request (IRQ) is a signal that informs the processor that a hardware device (e.g. mouse, keyboard, etc.) needs attention. The interrupt suspends the current activity of the processor in order to handle the external event.
Copy [root@linuxmaster ~ ]# ls -l /proc/irq/
total 0
dr-xr-xr-x. 2 root root 0 Sep 10 12:02 0
dr-xr-xr-x. 3 root root 0 Sep 10 12:02 1
dr-xr-xr-x. 2 root root 0 Sep 10 12:02 10
dr-xr-xr-x. 2 root root 0 Sep 10 12:02 11
dr-xr-xr-x. 3 root root 0 Sep 10 12:02 12
dr-xr-xr-x. 2 root root 0 Sep 10 12:02 13
dr-xr-xr-x. 2 root root 0 Sep 10 12:02 14
dr-xr-xr-x. 2 root root 0 Sep 10 12:02 15 The hdparm Utility
This utility is used to view information about or set SATA/IDE device parameters. Devices of this type will be /dev/hd*.
Command Description Display information about the drive
Get or set the using_dma flag for the drive
Test timings of device reads (or cache with -T) for comparison
The sdparm Utility
List or change SCSI/SATA device parameters and send simple SCSI commands. Devices of this type will be /dev/dd*.
Command Description List all known fields for a device
sdparm --command=CMD /dev/sda
Send a SCSI command to the device (e.g. eject, start, stop, etc.)
Copy [root@linuxmaster ~ ]# sdparm /dev/sda
/dev/sda: QEMU QEMU HARDDISK 2.5+
Read write error recovery mode page:
AWRE 1 [cha: n, def: 1]
ARRE 0 [cha: n, def: 0]
PER 0 [cha: n, def: 0]
Caching (SBC) mode page:
WCE 1 [cha: y, def: 1]
RCD 0 [cha: n, def: 0]
The nvme Utility
A command line utility for managing PCI Express-based devices. Devices of this type will be /dev/nvme*.
Command Description Display a list of available commands
List all NVMe controllers
nvme smart-log /dev/nvme0n1
nvme read/write /dev/nvme0n1 [options]
Issue IO read or write command
Copy [root@linuxmaster ~ ]# nvme list
Node Generic SN Model Namespace Usage Format FW Rev
--------------------- --------------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- --------
/dev/nvme0n1 /dev/ng0n1 S5EFNE0N501948 SAMSUNG MZVLB256HBHQ-00A00 1 54.53 GB / 256.06 GB 512 B + 0 B EXH7201Q The fstrim Utility
A command line utiliy for discarding unwanted block on a mounted filesystem.
Discards all unused blocks by default but provides options to modify this behavior based on range or size.
Systemd provides a timer for fstrim called fstrim.timer that runs on a weekly basis when enabled.
The -a option will run fstrim against all mounted file systems.
The discard option can be set in /etc/fstab for automatic online TRIM (not recommended).
Copy [root@linuxmaster ~ ]# fstrim -v /mnt/util
/: 615.5 MiB (173498368 bytes ) trimmed
[root@linuxmaster ~ ]# cat /usr/lib/systemd/system/fstrim.timer
[Unit]
Description = Discard unused blocks once a week
Documentation = man:fstrim
ConditionVirtualization = !container
ConditionPathExists = !/etc/initrd-release
[Timer]
OnCalendar = weekly
AccuracySec = 1h
Persistent = true
RandomizedDelaySec = 6000
[Install]
WantedBy = timers.target iSCSI
iSCSI (Internet Small Computer System Interface): A protocol that allows SCSI commands to be sent over a TCP/IP network. Communication takes place between an initiator (the cliant) and a target (a server).
ATA over Ethernet (AoE): Allows the Advanced Technology Attachment (ATA) protocol over an ethernet network
Fiber Channel over Ethernet (FCoE): Allows the Fiber Channel (FC) protocol over an ethernet network
targetcli: A shell for viewing, editing and saving the configuration of the kernel's target subsystem.
Creating an iSCSI Target:
Create a backstore using nvme1n1.
Create a target with a unique iSCSI Qualified Name (IQN).
Create an ACL, LUN, and portal within the target portal group (TPG)
ACLs : Access control lists
Portal : The IP and TCP port pair for an iSCSI target
Copy [root@linuxmaster ~ ]# targetcli ls
... Files and Utilities for the iSCSI Initiator
iscsid.conf: The default configuration file for iSCSI. It contains settings used by iscsid and iscsiadm.
initaltorname.iscsi: Contains the iSCSI initiator name. This should mirror the name from the ACL of the iSCSI target.
iscsid: A system daemon that manages iSCSI connections.
scsi_id: A utility used to retrieve and generate a unique SCSI identifier. This is primarity used by other utilities such as udev.
iscsiadm: The open-iscsi administration utility.
Copy iscsiadm -m < mod e > [options] Option Description Specify the discovery type
Login to a specified record
Use target portal with IP address and port
Copy [root@linuxmaster ~ ]# cat /etc/iscsi/initiatorname.iscsi
<< Add custom initiator name
[root@linuxmaster ~]# iscsiadm -m discovery -t st -p ip_address
<<Discover the iSCSI target
[root@linuxmaster ~]# iscsiadm -m node -T iqn.2022-09.com.name.host:t1 -l
<<Login to the target with the discovered IQN
[root@linuxmaster ~]# grep "Attached SCSI" /var/log/messages
<<View the iSCSI disk name
[root@linuxmaster ~]# iscsiadm -m node -T iqn.2022-09.com.name.host:t1 -u
<<Log off the iSCSI target204.3 Logical Volume Manager (weight: 3)
Copy [root@linuxmaster ~ ]# yum install -y targetctl
...
[root@linuxmaster ~ ]# targetcli
targetcli shell version 2.1.53
Copyright 2011-2013 by Datera, Inc and others.
For help on commands, type 'help' .
/ > backstores/block create block01 /dev/nvme1n1
Created block storage object block01 using /dev/nvme1n1.
/ > iscsi/ create iqn.2022-09.com.linuxmaster:linuxmaster1
Created target iqn.2022-09.com.linuxmaster:linuxmaster1.
Created TPG 1.
Global pref auto_add_default_portal= true
Created default portal listening on all IPs (0.0.0.0), port 3260.
/ > ls
o- / ............................................................................................. [...]
o- backstores .................................................................................. [...]
| o- block ...................................................................... [Storage Objects: 1]
| | o- block01 ........................................ [/dev/nvme1n1 (2.0GiB) write-thru deactivated]
| | o- alua ....................................................................... [ALUA Groups: 1]
| | o- default_tg_pt_gp ........................................... [ALUA state: Active/optimized]
| o- fileio ..................................................................... [Storage Objects: 0]
| o- pscsi ...................................................................... [Storage Objects: 0]
| o- ramdisk .................................................................... [Storage Objects: 0]
o- iscsi ................................................................................ [Targets: 1]
| o- iqn.2022-09.com.linuxmaster:linuxmaster1 .............................................. [TPGs: 1]
| o- tpg1 ................................................................... [no-gen-acls, no-auth]
| o- acls .............................................................................. [ACLs: 0]
| o- luns .............................................................................. [LUNs: 0]
| o- portals ........................................................................ [Portals: 1]
| o- 0.0.0.0:3260 ......................................................................... [OK]
o- loopback ............................................................................. [Targets: 0]
/ > cd iscsi/iqn.2022-09.com.linuxmaster:linuxmaster1/tpg1/
/iscsi/iqn.20...xmaster1/tpg1 > luns/ create /backstores/block/block01
Created LUN 0.
/iscsi/iqn.20...xmaster1/tpg1 > acls/ create iqn.2022-09.com.linuxmaster.acg02:master
Created Node ACL for iqn.2022-09.com.linuxmaster.acg02:master
Created mapped LUN 0.
/iscsi/iqn.20...xmaster1/tpg1 > cd /
/ > ls
o- / ............................................................................................. [...]
o- backstores .................................................................................. [...]
| o- block ...................................................................... [Storage Objects: 1]
| | o- block01 .......................................... [/dev/nvme1n1 (2.0GiB) write-thru activated]
| | o- alua ....................................................................... [ALUA Groups: 1]
| | o- default_tg_pt_gp ........................................... [ALUA state: Active/optimized]
| o- fileio ..................................................................... [Storage Objects: 0]
| o- pscsi ...................................................................... [Storage Objects: 0]
| o- ramdisk .................................................................... [Storage Objects: 0]
o- iscsi ................................................................................ [Targets: 1]
| o- iqn.2022-09.com.linuxmaster:linuxmaster1 .............................................. [TPGs: 1]
| o- tpg1 ................................................................... [no-gen-acls, no-auth]
| o- acls .............................................................................. [ACLs: 1]
| | o- iqn.2022-09.com.linuxmaster.acg02:master ................................. [Mapped LUNs: 1]
| | o- mapped_lun0 ................................................... [lun0 block/block01 (rw)]
| o- luns .............................................................................. [LUNs: 1]
| | o- lun0 .................................... [block/block01 (/dev/nvme1n1) ( default_tg_pt_gp )]
| o- portals ........................................................................ [Portals: 1]
| o- 0.0.0.0:3260 ......................................................................... [OK]
o- loopback ............................................................................. [Targets: 0]
/ > exit
Global pref auto_save_on_exit= true
Last 10 configs saved in /etc/target/backup/.
Configuration saved to /etc/target/saveconfig.json
[root@linuxmaster ~ ]# systemctl enable target.service --now
Created symlink from /etc/systemd/system/multi-user.target.wants/target.service to /usr/lib/systemd/system/target.service.
[root@linuxmaster ~ ]# yum install -y iscsi-initiator-utils
...
[root@linuxmaster ~ ]# vim /etc/iscsi/initiatorname.iscsi
InitiatorName = iqn.2022-09.com.linuxmaster.acg02:master
[root@linuxmaster ~ ]# systemctl enable iscsid --now
Created symlink from /etc/systemd/system/multi-user.target.wants/iscsid.service to /usr/lib/systemd/system/iscsid.service.
[root@linuxmaster ~ ]# systemctl status iscsid
● iscsid.service - Open-iSCSI
Loaded: loaded (/usr/lib/systemd/system/iscsid.service; enabled ; vendor preset: disabled )
Active: active (running) since Tue 2022-09-13 12:06:34 UTC; 20s ago
Docs: man:iscsid ( 8 )
man:iscsiuio(8 )
man:iscsiadm(8 )
Main PID: 4125 (iscsid)
Status: "Ready to process requests"
CGroup: /system.slice/iscsid.service
└─4125 /sbin/iscsid -f
Sep 13 12:06:34 linuxmaster systemd[1]: Starting Open-iSCSI...
Sep 13 12:06:34 linuxmaster systemd[1]: Started Open-iSCSI.
[root@linuxmaster ~ ]# iscsiadm -m discovery -t st -p 172.31.28.253
172.31.28.253:3260,1 iqn.2022-09.com.linuxmaster:linuxmaster1
[root@linuxmaster ~ ]# iscsiadm -m node -T iqn.2022-09.com.linuxmaster:linuxmaster1 -l
Logging in to [iface: default, target: iqn.2022-09.com.linuxmaster:linuxmaster1, portal: 172.31.28.253,3260] (multiple)
Login to [iface: default, target: iqn.2022-09.com.linuxmaster:linuxmaster1, portal: 172.31.28.253,3260] successful.
[root@linuxmaster ~ ]# grep "Attached SCSI" /var/log/messages
Sep 13 12:08:17 ip-172-31-28-253 kernel: sd 0:0:0:0: [sda] Attached SCSI disk
[root@linuxmaster ~ ]# ll /dev/sda
brw-rw----. 1 root disk 8, 0 Sep 13 12:08 /dev/sda
[root@linuxmaster ~ ]# ll /dev/disk/by-id/
total 0
lrwxrwxrwx. 1 root root 13 Sep 13 11:50 nvme-Amazon_Elastic_Block_Store_vol09bb3f1a4dc9b3cbe - > ../../nvme0n1
lrwxrwxrwx. 1 root root 15 Sep 13 11:50 nvme-Amazon_Elastic_Block_Store_vol09bb3f1a4dc9b3cbe-part1 - > ../../nvme0n1p1
lrwxrwxrwx. 1 root root 13 Sep 13 12:01 nvme-Amazon_Elastic_Block_Store_vol0d17c9387510b69db - > ../../nvme1n1
lrwxrwxrwx. 1 root root 13 Sep 13 11:50 nvme-nvme.1d0f-766f6c3039626233663161346463396233636265-416d617a6f6e20456c617374696320426c6f636b2053746f7265-00000001 -> ../../nvme0n1
lrwxrwxrwx. 1 root root 15 Sep 13 11:50 nvme-nvme.1d0f-766f6c3039626233663161346463396233636265-416d617a6f6e20456c617374696320426c6f636b2053746f7265-00000001-part1 -> ../../nvme0n1p1
lrwxrwxrwx. 1 root root 13 Sep 13 12:01 nvme-nvme.1d0f-766f6c3064313763393338373531306236396462-416d617a6f6e20456c617374696320426c6f636b2053746f7265-00000001 -> ../../nvme1n1
lrwxrwxrwx. 1 root root 9 Sep 13 12:08 scsi-36001405b58213e8e6e647d4ad9139dea - > ../../sda
lrwxrwxrwx. 1 root root 9 Sep 13 12:08 wwn-0x6001405b58213e8e6e647d4ad9139dea - > ../../sda
[root@linuxmaster ~ ]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 2G 0 disk
nvme0n1 259:0 0 20G 0 disk
└─nvme0n1p1 259:1 0 20G 0 part /
nvme1n1 259:2 0 2G 0 disk
[root@linuxmaster ~ ]# iscsiadm -m session -P 1
Target: iqn.2022-09.com.linuxmaster:linuxmaster1 (non-flash)
Current Portal: 172.31.28.253:3260,1
Persistent Portal: 172.31.28.253:3260,1
**********
Interface:
**********
Iface Name: default
Iface Transport: tcp
Iface Initiatorname: iqn.2022-09.com.linuxmaster.acg02:master
Iface IPaddress: 172.31.28.253
Iface HWaddress: < empt y >
Iface Netdev: < empt y >
SID: 1
iSCSI Connection State: LOGGED IN
iSCSI Session State: LOGGED_IN
Internal iscsid Session State: NO CHANGE
[root@linuxmaster ~ ]# iscsiadm -m node -P 1
Target: iqn.2022-09.com.linuxmaster:linuxmaster1
Portal: 172.31.28.253:3260,1
Iface Name: default 204.3 Logical Volume Manager (weight: 3)
Candidates should be able to create and remove logical volumes, volume groups, and physical volumes. This objective includes snapshots and resizing logical volumes.
Key Knowledge Areas:
Resizing, renaming, creating, and removing logical volumes, volume groups, and physical volumes
Creating and maintaining snapshots
The following is a partial list of the used files, terms and utilities:
LVM Architecture
Working with Physical Volumes
Command Purpose Create (initialize) a physical volume from a block device
Display info about physical volumes
Display verbose info about physical volumes
Scan all supported LVM block devices
Update the size of a physical volume
Copy [root@linuxmaster ~ ]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 19.1G 0 disk
└─sda1 8:1 0 19.1G 0 part /
sdb 8:16 0 10G 0 disk
├─sdb1 8:17 0 1G 0 part
└─sdb2 8:18 0 1G 0 part
sdc 8:32 0 10G 0 disk
├─sdc1 8:33 0 1G 0 part
└─sdc2 8:34 0 1G 0 part
sr0 11:0 1 1024M 0 rom
[root@linuxmaster ~ ]# pvcreate /dev/sdb{ 1,2} /dev/sdc{1,2}
Physical volume "/dev/sdb1" successfully created.
Physical volume "/dev/sdb2" successfully created.
Physical volume "/dev/sdc1" successfully created.
Physical volume "/dev/sdc2" successfully created.
[root@linuxmaster ~ ]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 lvm2 --- 1.00g 1.00g
/dev/sdb2 lvm2 --- 1.00g 1.00g
/dev/sdc1 lvm2 --- 1.00g 1.00g
/dev/sdc2 lvm2 --- 1.00g 1.00g
[root@linuxmaster ~ ]# pvscan
PV /dev/sdc1 lvm2 [1.00 GiB]
PV /dev/sdb2 lvm2 [1.00 GiB]
PV /dev/sdc2 lvm2 [1.00 GiB]
PV /dev/sdb1 lvm2 [1.00 GiB]
Total: 4 [4.00 GiB] / in use: 0 [0 ] / in no VG: 4 [4.00 GiB]
[root@linuxmaster ~ ]# pvdisplay
"/dev/sdc1" is a new physical volume of "1.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc1
VG Name
PV Size 1.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID yayebB-OerJ-U7IE-Ww8h-M1N6-l0dl-ezcXrS
"/dev/sdb2" is a new physical volume of "1.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb2
VG Name
PV Size 1.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID O5PA7y-HqOx-q69t-Vret-V9UZ-RqH8-NJuHqB
"/dev/sdc2" is a new physical volume of "1.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc2
VG Name
PV Size 1.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID bOKd2X-yHB3-w0xS-t8JU-uq95-VksQ-KZ0LM6
"/dev/sdb1" is a new physical volume of "1.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 1.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID hzCENy-Pic3-8Z9D-Legi-JacD-G6oj-ucfuTM Working with Volume Group
Command Purpose Create a volume group from physical volumes
Add a physical volume to a volume group
Remove a physical volume from a volume group
Display information about volume groups
Display verbose information about volume groups
Display information about volume groups and rebuild the LVM cache
Modify attributes of a volume group
Change the name of a volume group
Copy [root@linuxmaster ~ ]# vgcreate data_vg /dev/sdb{ 1,2}
Volume group "data_vg" successfully created
root@linuxmaster ~]# vgs
VG #PV #LV #SN Attr VSize VFree
data_vg 2 0 0 wz--n- 1.99g 1.99g
[root@linuxmaster ~ ]# vgscan
Reading volume groups from cache.
Found volume group "data_vg" using metadata type lvm2
[root@linuxmaster ~ ]# vgdisplay
--- Volume group ---
VG Name data_vg
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 2
Act PV 2
VG Size 1.99 GiB
PE Size 4.00 MiB
Total PE 510
Alloc PE / Size 0 / 0
Free PE / Size 510 / 1.99 GiB
VG UUID z5kweM-C1aR-egdJ-IefJ-f1Bz-VGDC-EXcQzx
[root@linuxmaster ~ ]# vgextend data_vg /dev/sdc{ 1,2}
Volume group "data_vg" successfully extended
[root@linuxmaster ~ ]# vgs
VG #PV #LV #SN Attr VSize VFree
data_vg 4 0 0 wz--n- 3.98g 3.98g Working with Logical Volumes
Command Purpose Create a logical volume from a volume group
-l - Specify the number of extends or extent percentage
Display info about logical volumes
Display verbose info about logical volumes
List all logical volumes in all volume groups
Change the name of a logical volume
Adjust the parameters of a logical volume
Remove a logical volume from a volume group
Copy [root@linuxmaster ~ ]# lvcreate -L 1G -n backup data_vg
Logical volume "backup" created.
[root@linuxmaster ~ ]# lvcreate -l 500 -n temp data_vg
Logical volume "temp" created.
[root@linuxmaster ~ ]# lvcreate -l 50%FREE -n current data_vg
Logical volume "current" created.
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-a----- 1.00g
current data_vg -wi-a----- 528.00m
temp data_vg -wi-a----- 1.95g
[root@linuxmaster ~ ]# lvdisplay
--- Logical volume ---
LV Path /dev/data_vg/backup
LV Name backup
VG Name data_vg
LV UUID a2GDAc-WoFl-QVQ5-E4YD-ylhX-7RPT-w7B462
LV Write Access read/write
LV Creation host, time linuxmaster, 2022-09-13 14:26:00 +0000
LV Status available
# open 0
LV Size 1.00 GiB
Current LE 256
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Logical volume ---
LV Path /dev/data_vg/temp
LV Name temp
VG Name data_vg
LV UUID AAtwqm-CtbZ-9AdO-SLDJ-F61m-gIXc-rxK22j
LV Write Access read/write
LV Creation host, time linuxmaster, 2022-09-13 14:26:53 +0000
LV Status available
# open 0
LV Size 1.95 GiB
Current LE 500
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/data_vg/current
LV Name current
VG Name data_vg
LV UUID yRgoQq-u5d2-FiqW-ijZ5-538q-aH1I-UVWOQ0
LV Write Access read/write
LV Creation host, time linuxmaster, 2022-09-13 14:28:10 +0000
LV Status available
# open 0
LV Size 528.00 MiB
Current LE 132
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
[root@linuxmaster ~ ]# lvremove /dev/data_vg/temp
Do you really want to remove active logical volume data_vg/temp? [y/n]: y
Logical volume "temp" successfully removed
[root@linuxmaster ~ ]# lvscan
ACTIVE '/dev/data_vg/backup' [1.00 GiB] inherit
ACTIVE '/dev/data_vg/current' [528.00 MiB] inherit
Copy [root@linuxmaster ~ ]# mkfs.ext4 /dev/data_vg/backup
mke2fs 1.42.9 (28-Dec-2013)
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size= 4096 (log=2)
Fragment size= 4096 (log=2)
Stride = 0 blocks, Stripe width= 0 blocks
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block= 0
Maximum filesystem blocks= 268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks ): done
Writing superblocks and filesystem accounting information: done
[root@linuxmaster ~ ]# mkfs.ext4 /dev/data_vg/current
mke2fs 1.42.9 (28-Dec-2013)
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size= 4096 (log=2)
Fragment size= 4096 (log=2)
Stride = 0 blocks, Stripe width= 0 blocks
33840 inodes, 135168 blocks
6758 blocks (5.00%) reserved for the super user
First data block= 0
Maximum filesystem blocks= 138412032
5 block groups
32768 blocks per group, 32768 fragments per group
6768 inodes per group
Superblock backups stored on blocks:
32768, 98304
Allocating group tables: done
Writing inode tables: done
Creating journal (4096 blocks ): done
Writing superblocks and filesystem accounting information: done
[root@linuxmaster ~ ]# mkdir /mnt/backup
[root@linuxmaster ~ ]# mkdir /mnt/current
[root@linuxmaster ~ ]# mount -t ext4 /dev/data_vg/backup /mnt/backup/
[root@linuxmaster ~ ]# mount -t ext4 /dev/data_vg/current /mnt/current/
[root@linuxmaster ~ ]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 871M 0 871M 0% /dev
tmpfs 895M 0 895M 0% /dev/shm
tmpfs 895M 8.6M 887M 1% /run
tmpfs 895M 0 895M 0% /sys/fs/cgroup
/dev/sda1 19G 1.1G 17G 6% /
tmpfs 179M 0 179M 0% /run/user/0
/dev/mapper/data_vg-backup 976M 2.6M 907M 1% /mnt/backup
/dev/mapper/data_vg-current 504M 804K 466M 1% /mnt/current Resizing Logical Volumes
Command Purpose Grow the size of a logical volume
-l - Specify the number of extens or extent percentage
-r - Resize the underlying file system
Display info about logical volumes
Resize an ext2/ext3/ext4 filesystem
Reduce the size of a logical volume
Copy [root@linuxmaster ~ ]# vgs
VG #PV #LV #SN Attr VSize VFree
data_vg 4 2 0 wz--n- 3.98g < 2.47g
[root@linuxmaster ~ ]# lvextend -L +500M /dev/data_vg/backup
Size of logical volume data_vg/backup changed from 1.00 GiB (256 extents ) to < 1.49 GiB ( 381 extents ).
Logical volume data_vg/backup successfully resized.
[root@linuxmaster ~ ]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 871M 0 871M 0% /dev
tmpfs 895M 0 895M 0% /dev/shm
tmpfs 895M 8.6M 887M 1% /run
tmpfs 895M 0 895M 0% /sys/fs/cgroup
/dev/sda1 19G 1.1G 17G 6% /
tmpfs 179M 0 179M 0% /run/user/0
/dev/mapper/data_vg-backup 976M 2.6M 907M 1% /mnt/backup
/dev/mapper/data_vg-current 504M 804K 466M 1% /mnt/current
[root@linuxmaster ~ ]# resize2fs /dev/data_vg/backup
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/data_vg/backup is mounted on /mnt/backup ; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/data_vg/backup is now 390144 blocks long.
[root@linuxmaster ~ ]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 871M 0 871M 0% /dev
tmpfs 895M 0 895M 0% /dev/shm
tmpfs 895M 8.6M 887M 1% /run
tmpfs 895M 0 895M 0% /sys/fs/cgroup
/dev/sda1 19G 1.1G 17G 6% /
tmpfs 179M 0 179M 0% /run/user/0
/dev/mapper/data_vg-backup 1.5G 3.0M 1.4G 1% /mnt/backup
/dev/mapper/data_vg-current 504M 804K 466M 1% /mnt/current
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-ao---- < 1.49g
current data_vg -wi-ao---- 528.00m
[root@linuxmaster ~ ]# lvreduce -l 100 -r data_vg/current
Do you want to unmount "/mnt/current" ? [Y | n] y
fsck from util-linux 2.23.2
/dev/mapper/data_vg-current: 11/33840 files (0.0% non-contiguous ), 6428/135168 blocks
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/mapper/data_vg-current to 102400 (4k) blocks.
The filesystem on /dev/mapper/data_vg-current is now 102400 blocks long.
Size of logical volume data_vg/current changed from 528.00 MiB (132 extents ) to 400.00 MiB ( 100 extents ).
Logical volume data_vg/current successfully resized.
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-ao---- < 1.49g
current data_vg -wi-ao---- 400.00m Creating and Managing Snapshots
Command Purpose Create a logical volume
-l - Specify the number of extents or extent percentage
Display info about logical volumes
Increate the size of a logical volume or snapshot (COW table)
Reduce the size of a logical volume or snapshot (COW table)
Remove a logical volume or a snapshot
Adjust the parameters of a logical volume
Change logical volume layout
--merge - Merge a snapshot logical volume into its origin
Copy [root@linuxmaster ~ ]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 871M 0 871M 0% /dev
tmpfs 895M 0 895M 0% /dev/shm
tmpfs 895M 8.6M 887M 1% /run
tmpfs 895M 0 895M 0% /sys/fs/cgroup
/dev/sda1 19G 1.1G 17G 6% /
tmpfs 179M 0 179M 0% /run/user/0
/dev/mapper/data_vg-current 976M 2.6M 907M 1% /mnt/current
/dev/mapper/data_vg-backup 976M 2.6M 907M 1% /mnt/backup
[root@linuxmaster ~ ]# touch /mnt/current/test{ 1..5}.txt
[root@linuxmaster ~ ]# ll /mnt/current/
total 16
drwx------. 2 root root 16384 Sep 13 15:02 lost+found
-rw-r--r--. 1 root root 0 Sep 13 15:03 test1.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test2.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test3.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test4.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test5.txt
[root@linuxmaster ~ ]# lvcreate -l 25%ORIGIN -s -n cur_snap1 /dev/mapper/data_vg-current
Logical volume "cur_snap1" created.
[root@linuxmaster ~ ]# lvcreate -L 100M -s -n cur_snap2 /dev/mapper/data_vg-current
Logical volume "cur_snap2" created.
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-ao---- 1.00g
cur_snap1 data_vg swi-a-s--- 264.00m current 0.01
cur_snap2 data_vg swi-a-s--- 100.00m current 0.01
current data_vg owi-aos--- 1.00g
temp data_vg -wi-a----- 1.00g
[root@linuxmaster ~ ]# cp -r /etc/ /mnt/current/
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-ao---- 1.00g
cur_snap1 data_vg swi-a-s--- 264.00m current 1.14
cur_snap2 data_vg swi-a-s--- 100.00m current 3.01
current data_vg owi-aos--- 1.00g
[root@linuxmaster ~ ]# lvdisplay /dev/data_vg/cur_snap1
--- Logical volume ---
LV Path /dev/data_vg/cur_snap1
LV Name cur_snap1
VG Name data_vg
LV UUID giAvbe-z4kn-CWDp-cvZx-Vn8U-N86W-bUwEze
LV Write Access read/write
LV Creation host, time linuxmaster, 2022-09-13 15:05:37 +0000
LV snapshot status active destination for current
LV Status available
# open 0
LV Size 1.00 GiB
Current LE 256
COW-table size 264.00 MiB
COW-table LE 66
Allocated to snapshot 14.26%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:5
[root@linuxmaster ~ ]# lvextend -l 50%ORIGIN /dev/mapper/data_vg-cur_snap1
Size of logical volume data_vg/cur_snap1 changed from 264.00 MiB (66 extents ) to 512.00 MiB ( 128 extents ).
Logical volume data_vg/cur_snap1 successfully resized.
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-ao---- 1.00g
cur_snap1 data_vg swi-a-s--- 512.00m current 7.47
cur_snap2 data_vg swi-a-s--- 100.00m current 38.23
current data_vg owi-aos--- 1.00g
[root@linuxmaster ~ ]# lvremove data_vg/cur_snap2
Do you really want to remove active logical volume data_vg/cur_snap2? [y/n]: y
Logical volume "cur_snap2" successfully removed
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-ao---- 1.00g
cur_snap1 data_vg swi-a-s--- 512.00m current 7.47
current data_vg owi-aos--- 1.00g
[root@linuxmaster ~ ]# mount /dev/mapper/data_vg-cur_snap1 /mnt/snap/
[root@linuxmaster ~ ]# ll /mnt/snap/
total 16
drwx------. 2 root root 16384 Sep 13 15:02 lost+found
-rw-r--r--. 1 root root 0 Sep 13 15:03 test1.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test2.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test3.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test4.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test5.txt
[root@linuxmaster ~ ]# ll /mnt/current/
total 20
drwxr-xr-x. 75 root root 4096 Sep 13 15:07 etc
drwx------. 2 root root 16384 Sep 13 15:02 lost+found
-rw-r--r--. 1 root root 0 Sep 13 15:03 test1.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test2.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test3.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test4.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test5.txt
[root@linuxmaster ~ ]# umount /mnt/current/
[root@linuxmaster ~ ]# umount /mnt/snap/
[root@linuxmaster ~ ]# lvchange -an /dev/data_vg/current
[root@linuxmaster ~ ]# lvconvert --merge data_vg/cur_snap1
Merging of snapshot data_vg/cur_snap1 will occur on next activation of data_vg/current.
[root@linuxmaster ~ ]# lvchange -ay /dev/data_vg/current
[root@linuxmaster ~ ]# mount /dev/data_vg/current /mnt/current/
[root@linuxmaster ~ ]# ll /mnt/current/
total 16
drwx------. 2 root root 16384 Sep 13 15:02 lost+found
-rw-r--r--. 1 root root 0 Sep 13 15:03 test1.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test2.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test3.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test4.txt
-rw-r--r--. 1 root root 0 Sep 13 15:03 test5.txt
[root@linuxmaster ~ ]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
backup data_vg -wi-ao---- 1.00g
current data_vg -wi-ao---- 1.00g Sample Questions
1. Which of the following are protocols used in a Storage Area Network (SAN)? (Choose three.)
2. What command is used to initialize a physical volume?
3. What command is used to add a physical volume to a volume group?
4. What option for the sdparm utility lists all known fields for a device?
5. What is the default configuration file for iSCSI?
6. What are two ways to gain information about a RAID? (Choose two.)
7. What subcommand for the nvme utility will display all NVMe controllers?
8. What option for the hdparm utility will retrieve or set parameters the using_dma option?
9. What mode is used to log in to an iSCSI target?
10. What component in a target portal group is added to initiatorname.iscsi for security?
11. What option is used to designate a logical volume as a snapshot?
12. What option is used to resize the underlying filesystem of a logical volume?
13. What option is used to specify the number of extents for a logical volume?
14. What type of technology allows hardware devices to bypass the CPU and communicate with system memory?
15. What partition type specifies a RAID partition?
16. What option is used to specify a RAID device as faulty?
17. What RAID level uses mirroring to prevent data loss?
18. What is the main configuration file for the management of software RAID with the mdadm utility?
19. What command is used to discard unwanted blocks on a mounted filesystem?
