RedHat LVM Doc

Logical Volume Manager

• disks or partitions are managed as Physical Volumes (PV)
  • pvcreate /dev/xda1
  • lvmdiskscan to identify all items which can be used as PVs
  • resize/remove the PVs w/ pvresize or pvremove
• more PVs can be merged/striped into Volume Group (VG)
  • vgcreate volgrp1 /dev/sdd1
  • adding PVs to VGs vgextend volgrp1 /dev/sde1
  • vgmerge / vgsplit
• more VGs can be merged into Logical Volumes (LV) - their size is considered in minimal extensible chunks, or extents
• LVs can be thin-provisioned, appearing as more available space than actual space due to sharing between clients
• SSDs can be used as cache for spinning disks
• clustering can be managed by the Clustered Logical Volume Manager (CLVM)

• LVs can be converted using lvconvert from RAID to linear and vice-versa

• LVs commands:
  • lvcreate -L 10G volgrp1 create liniar 10G volume
  • lvcreate -L 10G -i 2 -n stripedvol volgrp1 create striped 10G volume, number of stripes=2, name=stripedvol, default stripe size is 64KB
  • -m # of copies for RAID1
  • -i # of stripes for RAID 4/5/6
  • recovery rate can be throttled
  • -T to create a Thin pool
• lvs/pvs commands can be used in scripting or to monitor the status of the pools/volumes
• RAID 1/4/5/6/10
• details from https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Logical_Volume_Manager_Administration/index.html