Lvm advanced topics
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The document discusses advanced topics in Logical Volume Management (LVM) including data protection using mirroring, data migration between physical volumes, using LVM with multipath devices, and accessing LVM in a rescue environment. It provides examples of commands to build mirrored and striped logical volumes, recover from failed drives, migrate data between disks, and configure LVM to work with multipath devices.
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Lvm advanced topics
- 1. LVM Advanced Topics Will Sterling Linux & UNIX Consultant @ PARSEC Group
- 2. Agenda ● Logical Volume Manager Overview ● Data Protection ● Data migration ● LVM & Multipath Devices ● Using LVM in a Rescue environment LVM Advanced topics
- 3. LVM Overview ● Eliminates the need for partitions to manage disks ● Adds flexibility that partitions do not provide ● Provides RAID 0 and RAID 1 like functionality ● Logical Volumes can be created small and grown as needed much easier then a partition ● As useful on a laptop with one hard drive as it is on servers with hundreds of LUNs LVM Advanced topics
- 4. LVM Layout LVM Advanced topics
- 5. LVM Userland pvchange vgcfgbackup lvchange pvck vgcfgrestore lvconvert pvcreate vgchange lvcreate pvdisplay vgck lvdisplay pvmove vgconvert lvextend pvremove vgcreate lvreduce pvresize vgdisplay lvremove pvs vgexport lvrename pvscan vgextend lvresize vgimport lvs vgimportclone lvscan vgmerge vgmknodes vgreduce vgremove vgrename vgs vgscan vgsplit LVM Advanced topics
- 6. Data Protection with LVM ● Data is protected via LE mirroring. ● Mirrored logical volumes can span more then two storage devices in a RAID 0 + 1 like fashion. ● Does not provide parity data protection and can not be used to create RAID 3 - 6 logical volumes. LVM Advanced topics
- 7. Building A Mirrored Logical Volume [wills@localhost ~]$ sudo pvcreate /dev/vdb Physical volume "/dev/vdb" successfully created [wills@localhost ~]$ sudo pvcreate /dev/vdc Physical volume "/dev/vdc" successfully created [wills@localhost ~]$ sudo vgcreate VolGroup02 /dev/vdb /dev/vdc Volume group "VolGroup02" successfully created [wills@localhost ~]$ sudo lvcreate m1 L 508M corelog nosync n LogVol00 VolGroup02 WARNING: New mirror won't be synchronised. Don't read what you didn't write! Logical volume "LogVol00" created LVM Advanced topics
- 8. Building A Mirrored Logical Volume Continued [wills@localhost ~]$ sudo lvdisplay /dev/VolGroup02/LogVol00 Logical volume LV Name /dev/VolGroup02/LogVol00 VG Name VolGroup02 LV UUID S7PeP1QN2YVtxF0qjYzk7jcq6n8rJjvF LV Write Access read/write LV Status available # open 0 LV Size 508.00 MiB Current LE 127 Mirrored volumes 2 Segments 1 Allocation inherit Read ahead sectors auto currently set to 256 Block device 253:2 LVM Advanced topics
- 9. Recover Failed Drive Mirrored LV [wills@localhost ~]$ sudo lvdisplay v /dev/VolGroup02/LogVol00 Using logical volume(s) on command line Wiping cache of LVMcapable devices Couldn't find device with uuid pKWuz6XidZaqAS6GQG9OrB cyQWzOnRgp. There are 1 physical volumes missing. Logical volume LV Name /dev/VolGroup02/LogVol00 VG Name VolGroup02 LV UUID DtrdmhqT5MxjtNmD0tmcM2j3I7CCBJUA LV Write Access read/write LV Status available Snip LVM Advanced topics
- 10. Recover Failed Drive Mirrored LV Continued [wills@localhost ~]$ sudo pvcreate uuid pKWuz6XidZ aqAS6GQG9OrBcyQWzOnRgp restorefile /etc/lvm/archive/VolGroup02_00037.vg /dev/vde Couldn't find device with uuid pKWuz6XidZaqAS6GQG9OrB cyQWzOnRgp. Physical volume "/dev/vde" successfully created [wills@localhost ~]$ sudo vgcfgrestore f /etc/lvm/archive/VolGroup02_00037.vg VolGroup02 Restored volume group VolGroup02 [wills@localhost ~]$ sudo vgchange a y VolGroup02 1 logical volume(s) in volume group "VolGroup02" now active LVM Advanced topics
- 11. Building A Stripped & Mirrored Logical [wills@localhost ~]$ sudo pvcreate /dev/vdb Physical volume "/dev/vdb" successfully created [wills@localhost ~]$ sudo pvcreate /dev/vdd Physical volume "/dev/vdd" successfully created [wills@localhost ~]$ sudo pvcreate /dev/vdc Physical volume "/dev/vdc" successfully created [wills@localhost ~]$ sudo pvcreate /dev/vdf Physical volume "/dev/vdf" successfully created [wills@localhost ~]$ sudo vgcreate VolGroup02 /dev/vdb /dev/vdd /dev/vdf /dev/vde Volume group "VolGroup02" successfully created [wills@localhost ~]$ sudo lvcreate i2 I128 m 1 corelog L900M n LogVol00 VolGroup02 Rounding size (225 extents) up to stripe boundary size (226 extents) Logical volume "LogVol00" created LVM Advanced topics
- 17. LVM & Multipath Devices ● LVM scans the attached drives for its logical volumes at boot and when any LVM command is run. ● LVM must be configured so that it only finds each PV once! ● LVM will not start a Volume Group if it finds duplicate matches for a PV UUID. ● Limits on LVM's ability to find duplicate paths are implemented with a Filter in lvm.conf filter = [ "a/mpath.*/", "r/.*/" ] LVM Advanced topics
- 18. LVM in the Rescue Environment ● The many commands that comprise the LVM userland are all softlinks to /sbin/lvm ● Use the same commands you are used to using but prefix the command with "lvm " ● You may need to locate and active VGs and LVs ○ lvm vgscan ○ lvm vgchange -a y ● Any configuration settings that were needed in lvm.conf, i.e. "filter", will need to be passed on the command line with --config. ○ lvm vgscan --config 'devices{ filter = [ "a/mpath.*/", "r/.*/" ] }' LVM Advanced topics
- 19. LVM in the Rescue Environment ● LVM Administrator Guide: http://docs.redhat.com/docs/en- US/Red_Hat_Enterprise_Linux/6/html/Logical_Volume_Manager_ Administration/index.html ● LVM2 Project Wiki: http://sources.redhat.com/lvm2/wiki ● LVM2 Mailing List: https://www.redhat.com/mailman/listinfo/linux- lvm ● LVM2 Source Code:ftp://sources.redhat.com/pub/lvm2/ ● IRC Freenode #lvm ● linux@parsec.com ! LVM Advanced topics