With pvmove achieve online data relocation

This document (000020303) is provided subject to the disclaimer at the end of this document.

Environment

  • SUSE Linux Enterprise Server 12 
  • SUSE Linux Enterprise Server 15
  • SUSE Linux Enterprise Server for SAP Applications 12
  • SUSE Linux Enterprise Server for SAP Applications 15

Situation

There is not enough space for the PVs(sdc|sdd) in a VG, it is necessary to move part/all of the PEs to other PV(sde)
# pvs
  PV         VG  Fmt  Attr PSize  PFree 
  /dev/sdc   vg1 lvm2 a--   8.00m     0 
  /dev/sdd   vg1 lvm2 a--   8.00m     0 
  /dev/sde       lvm2 ---  30.00m 30.00m
# dd if=/dev/zero of=/mnt/img bs=1M count=15
# df -Th /mnt
Filesystem          Type  Size  Used Avail Use% Mounted on
/dev/mapper/vg1-lv1 ext4   15M   15M     0 100% /mnt
# pvdisplay /dev/sd{c,d} |grep PE 
  PE Size               4.00 MiB
  Total PE              2
  Free PE               0
  Allocated PE          2
  PE Size               4.00 MiB
  Total PE              2
  Free PE               0
  Allocated PE          2

 

Resolution

Observe the changes of physical extents (PEs) in each PV to verify the working process of 'pvmove'

Scenario 1:
Use 'pvmove' to move physical extents to destination PV
# pvdisplay /dev/sd{c,d} |grep PE 
  PE Size               4.00 MiB
  Total PE              2
  Free PE               0
  Allocated PE          2
  PE Size               4.00 MiB
  Total PE              2
  Free PE               0
  Allocated PE          2

# vgextend vg1 /dev/sde
  Volume group "vg1" successfully extended

# pvmove /dev/sdd /dev/sde
  /dev/sdd: Moved: 100.00%

# pvdisplay /dev/sd{c,d,e} |grep PE
  PE Size               4.00 MiB
  Total PE              2
  Free PE               0
  Allocated PE          2
  PE Size               4.00 MiB
  Total PE              2
  Free PE               2
  Allocated PE          0
  PE Size               4.00 MiB
  Total PE              7
  Free PE               5
  Allocated PE          2

Scenario 2:
Use 'pvmove' from one single Physical Volume to multiple different Physical Volumes
# pvdisplay /dev/sdc |grep 'Total PE'
  Total PE              2

# pvmove /dev/sdc:0 /dev/sdd
  /dev/sdc: Moved: 100.00%
# pvmove /dev/sdc:1 /dev/sde
  /dev/sdc: Moved: 100.00%

# pvdisplay /dev/sd{c,d,e} |grep PE
  PE Size               4.00 MiB
  Total PE              2
  Free PE               2
  Allocated PE          0
  PE Size               4.00 MiB
  Total PE              2
  Free PE               1
  Allocated PE          1
  PE Size               4.00 MiB
  Total PE              7
  Free PE               4
  Allocated PE          3

Tips
Large PV capacity for the real environment, pvmove command can take a long time to execute, you may want to run the command in the background to avoid display of progress updates in the foreground.
# pvmove -b /dev/sdX /dev/sdY
The following command reports the progress of the pvmove command as a percentage at ten second intervals.
# pvmove -i5 /dev/sdZ
 

Cause

Not enough Free PE to carry new data

Additional Information

More usage, please refer to the EXAMPLES chapter
# man pvmove
EXAMPLES
       Move all physical extents that are used by simple LVs on the specified PV to free physical extents elsewhere in the VG.
       pvmove /dev/sdb1

       Use a specific destination PV when moving physical extents.
       pvmove /dev/sdb1 /dev/sdc1

       Move extents belonging to a single LV.
       pvmove -n lvol1 /dev/sdb1 /dev/sdc1

       Rather than moving the contents of an entire device, it is possible to move a range of physical extents, for example numbers 1000 to 1999 inclusive  on  the  specified
       PV.
       pvmove /dev/sdb1:1000-1999

       A  range of physical extents to move can be specified as start+length. For example, starting from PE 1000. (Counting starts from 0, so this refers to the 1001st to the
       2000th PE inclusive.)
       pvmove /dev/sdb1:1000+1000

       Move a range of physical extents to a specific PV (which must have sufficient free extents).
       pvmove /dev/sdb1:1000-1999 /dev/sdc1

       Move a range of physical extents to specific new extents on a new PV.
       pvmove /dev/sdb1:1000-1999 /dev/sdc1:0-999

       If the source and destination are on the same disk, the anywhere allocation policy is needed.
       pvmove --alloc anywhere /dev/sdb1:1000-1999 /dev/sdb1:0-999

       The part of a specific LV present within in a range of physical extents can also be picked out and moved.
       pvmove -n lvol1 /dev/sdb1:1000-1999 /dev/sdc1

 

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:000020303
  • Creation Date: 28-Jun-2021
  • Modified Date:30-Jun-2021
    • SUSE Linux Enterprise Server
    • SUSE Linux Enterprise Server for SAP Applications

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