LVM will be installed by default on Redhat Linux installation.But sometimes if you select the minimum package installation method,LVM will not be installed.So you need to install LVM package separately .Here we will see the LVM installation method and if its already installed how to verify it .Logical volume manager has two versions and those are 1.LVM-1 2.LVM-2 . In this tutorials, we are going see about LVM2 which is default volume manager in Redhat Linux newer releases.
In later part we will see about disk operations on LVM. That will cover bringing the disk under LVM control,Replacing failed disk and Removing the disk from LVM.
1.1 Installation of LVM
1.Verify LVM is installed or not on the server.
[root@mylinz ~]# rpm -qa |grep -i lvm lvm2-libs-2.02.72-8.el6.x86_64 lvm2-2.02.72-8.el6.x86_64 [root@mylinz ~]#
2.Here LVM is already installed.If its not already installed,use yum to install LVM.
Here is the procedure to configure yum repo.
Here is the procedure to configure yum repo.
[root@mylinz ~]# yum install lvm2* Loaded plugins: refresh-packagekit, rhnplugin This system is not registered with RHN. RHN support will be disabled. Setting up Install Process Package lvm2-libs-2.02.72-8.el6.x86_64 already installed and latest version Package lvm2-2.02.72-8.el6.x86_64 already installed and latest version Resolving Dependencies --> Running transaction check ---> Package lvm2-cluster.x86_64 0:2.02.72-8.el6 set to be updated --> Finished Dependency Resolution Dependencies Resolved ============================================================================== Package Arch Version Repository Size ============================================================================== Installing: lvm2-cluster x86_64 2.02.72-8.el6 local-installation 304 k Transaction Summary ============================================================================== Install 1 Package(s) Upgrade 0 Package(s) Total download size: 304 k Installed size: 580 k Is this ok [y/N]: y Downloading Packages: Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : lvm2-cluster-2.02.72-8.el6.x86_64 1/1 Installed: lvm2-cluster.x86_64 0:2.02.72-8.el6 Complete! [root@mylinz ~]#
As per about output,LVM2 packages are already installed.But there is other package called lvm2-cluster is installed now.Its cluster logical volume manager.
3.Verify the installed LVM packages.
[root@mylinz ~]# rpm -qa |grep -i lvm lvm2-libs-2.02.72-8.el6.x86_64 lvm2-cluster-2.02.72-8.el6.x86_64 lvm2-2.02.72-8.el6.x86_64 [root@mylinz ~]#
4.Check the LVM version.
[root@mylinz ~]# lvm version LVM version: 2.02.72(2) (2010-07-28) Library version: 1.02.53 (2010-07-28) Driver version: 4.17.0 [root@mylinz ~]#
5.Use “help” sub command to see the list of commands on LVM.
[root@mylinz ~]# lvm help Available lvm commands: Use 'lvm help ' for more information dumpconfig Dump active configuration formats List available metadata formats help Display help for commands lvchange Change the attributes of logical volume(s) lvconvert Change logical volume layout lvcreate Create a logical volume lvdisplay Display information about a logical volume lvextend Add space to a logical volume lvmchange With the device mapper, this is obsolete and does nothing. lvmdiskscan List devices that may be used as physical volumes lvmsadc Collect activity data lvmsar Create activity report lvreduce Reduce the size of a logical volume lvremove Remove logical volume(s) from the system lvrename Rename a logical volume lvresize Resize a logical volume lvs Display information about logical volumes lvscan List all logical volumes in all volume groups pvchange Change attributes of physical volume(s) pvresize Resize physical volume(s) pvck Check the consistency of physical volume(s) pvcreate Initialize physical volume(s) for use by LVM pvdata Display the on-disk metadata for physical volume(s) pvdisplay Display various attributes of physical volume(s) pvmove Move extents from one physical volume to another pvremove Remove LVM label(s) from physical volume(s) pvs Display information about physical volumes pvscan List all physical volumes segtypes List available segment types vgcfgbackup Backup volume group configuration(s) vgcfgrestore Restore volume group configuration vgchange Change volume group attributes vgck Check the consistency of volume group(s) vgconvert Change volume group metadata format vgcreate Create a volume group vgdisplay Display volume group information vgexport Unregister volume group(s) from the system vgextend Add physical volumes to a volume group vgimport Register exported volume group with system vgmerge Merge volume groups vgmknodes Create the special files for volume group devices in /dev vgreduce Remove physical volume(s) from a volume group vgremove Remove volume group(s) vgrename Rename a volume group vgs Display information about volume groups vgscan Search for all volume groups vgsplit Move physical volumes into a new or existing volume group version Display software and driver version information [root@mylinz ~]#
1.2 LVM DISK OPERATIONS
If you want to use LVM, then you have to bring the disks in to LVM control using “pvcreate” command.
1.List the physical disks.
[root@mylinz ~]# [root@mylinz ~]# fdisk -l |grep /dev/ |grep -v dm Disk /dev/sdd doesn't contain a valid partition table Disk /dev/sde doesn't contain a valid partition table Disk /dev/sdf doesn't contain a valid partition table Disk /dev/sdg doesn't contain a valid partition table Disk /dev/dm-0 doesn't contain a valid partition table Disk /dev/dm-1 doesn't contain a valid partition table Disk /dev/sda: 21.5 GB, 21474836480 bytes /dev/sda1 * 1 64 512000 83 Linux /dev/sda2 64 2611 20458496 8e Linux LVM Disk /dev/sdb: 536 MB, 536870912 bytes /dev/sdb1 1 512 524272 8e Linux LVM Disk /dev/sdc: 536 MB, 536870912 bytes /dev/sdc1 1 512 524272 8e Linux LVM Disk /dev/sdd: 536 MB, 536870912 bytes Disk /dev/sde: 536 MB, 536870912 bytes Disk /dev/sdf: 5368 MB, 5368709120 bytes Disk /dev/sdg: 106 MB, 106954752 bytes [root@mylinz ~]#
2.Use “fdisk” to label disks with LVM flags.
[root@mylinz ~]# fdisk /dev/sdd
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x57899b26.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-512, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-512, default 512):
Using default value 512
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@mylinz ~]#
3.Verify disk label in fdisk.
[root@mylinz ~]# fdisk -l /dev/sdd Disk /dev/sdd: 536 MB, 536870912 bytes 64 heads, 32 sectors/track, 512 cylinders Units = cylinders of 2048 * 512 = 1048576 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x57899b26 Device Boot Start End Blocks Id System /dev/sdd1 1 512 524272 8e Linux LVM [root@mylinz ~]#
4.Use pvcreate command to bring the disk under LVM control.
[root@mylinz ~]# pvcreate /dev/sdd1 Physical volume "/dev/sdd1" successfully created [root@mylinz ~]#
5.If you are getting any error while bringing the disk to LVM control,use force flag.
[root@mylinz ~]# pvcreate -f /dev/sdd1 Physical volume "/dev/sdd1" successfully created [root@mylinz ~]#
6.Verify your work.
[root@mylinz ~]# pvs /dev/sdd1 PV VG Fmt Attr PSize PFree /dev/sdd1 lvm2 a- 511.98m 511.98m [root@mylinz ~]#
How to replace a failed DISK in LVM ?
Now most of the Linux servers are using SAN boxes for data storage.So the disk failure rate is very less compare to internal disks. But in some cases customer would like use internal disks for the LVM volumes.Here we will see how to replace a failed disk if the volume is mirrored. If any disk got failed for non-mirror volume then there is no way to recover the data and its better to remove the volume and recreate it with good disk.
High Level Plan:
1.Find out which disk is failed and what are the mirrored volumes are affected
2.Remove the volume from the diskgroup forcefully
3.Replace a new disk
4.Add a new mirror to the volumes which are affected.
Thank you for reading this article.