HOWTO convert to/from striped LV

Converting from striped volume

Inital configuration is following: VG vgtest consist from 4x2g disks with one striped LV over all disks.

# pvs
  PV         VG     Fmt  Attr PSize  PFree
  /dev/sdb   rootvg lvm2 a--  19.97g   6.75g
  /dev/sdc   vgtest lvm2 a--   2.00g 508.00m
  /dev/sdd   vgtest lvm2 a--   2.00g 508.00m
  /dev/sde   vgtest lvm2 a--   2.00g 508.00m
  /dev/sdf   vgtest lvm2 a--   2.00g 508.00m
  /dev/sdg          lvm2 ---  16.00g  16.00g

# lvdisplay -m /dev/vgtest/data                                       
  --- Logical volume ---                                                                        
  LV Path                /dev/vgtest/data                                                       
  LV Name                data                                                                   
  VG Name                vgtest                                                                 
  LV UUID                5a9j6n-lIM8-LnFQ-i646-Q9W6-4cH9-1s3Qih                                 
  LV Write Access        read/write                                                             
  LV Creation host, time tmplt6-64, 2015-07-20 08:50:03 +0000                                   
  LV Status              available                                                              
  # open                 0                                                                      
  LV Size                6.00 GiB                                                               
  Current LE             1536                                                                   
  Segments               1                                                                      
  Allocation             inherit                                                                
  Read ahead sectors     auto                                                                   
  - currently set to     1024                                                                   
  Block device           253:7                                                                  
                                                                                                
  --- Segments ---                                                                              
  Logical extents 0 to 1535:                                                                    
    Type                striped                                                                 
    Stripes             4                                                                       
    Stripe size         64.00 KiB                                                               
    Stripe 0:                                                                                   
      Physical volume   /dev/sdc                                                                
      Physical extents  0 to 383                                                                
    Stripe 1:                                                                                   
      Physical volume   /dev/sdd                                                                
      Physical extents  0 to 383                                                                
    Stripe 2:                                                                                   
      Physical volume   /dev/sdf                                                                
      Physical extents  0 to 383                                                                
    Stripe 3:                                                                                   
      Physical volume   /dev/sde                                                                
      Physical extents  0 to 383                                                                

The task is to migrate it online to other single disk as non stiped logical volume. Add destination disk (PV) to VG:

# pvcreate --dataalignment 4k /dev/sdg
# vgextend vgtest /dev/sdg
  Volume group "vgtest" successfully extended

Add mirror chain to striped LV on new PV:

# lvconvert -b -m1 /dev/vgtest/data /dev/sdg
  Logical volume data converted.
# lvs -a -o +devices | grep -v rootvg
  LV              VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log       Cpy%Sync Convert Devices
  data            vgtest mwi-aom---   6.00g                                data_mlog 93.29            data_mimage_0(0),data_mimage_1(0)
  [data_mimage_0] vgtest Iwi-aom---   6.00g                                                           /dev/sdc(0),/dev/sdd(0),/dev/sdf(0),/dev/sde(0)
  [data_mimage_1] vgtest Iwi-aom---   6.00g                                                           /dev/sdg(0)
  [data_mlog]     vgtest lwi-aom---   4.00m                                                           /dev/sdg(1536)

Repeat command until Cpy%Sync becomes 100 (mirror in sync), then break mirror, removing stripped chain:

# lvconvert -m0 /dev/vgtest/data /dev/sdc /dev/sdd /dev/sdf /dev/sde
  Logical volume data converted.
# lvs -a -o +devices | grep -v rootvg
  LV    VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert Devices
  data  vgtest -wi-ao----   6.00g
# vgreduce vgtest /dev/sdc /dev/sdd /dev/sde /dev/sdf
  Removed "/dev/sdc" from volume group "vgtest"
  Removed "/dev/sdd" from volume group "vgtest"
  Removed "/dev/sde" from volume group "vgtest"
  Removed "/dev/sdf" from volume group "vgtest"

Finally remove physical devices from VG, then unconfigure SCSI device and unmap source LUNs.

Converting to striped volume

Now we have an opposite situation, we have a plain LV that want convert to striped. Add desired amount of LUNs accoring to stripes amount, and rescan SCSI bus. Create PV and add them to VG:

# pvs
  PV         VG     Fmt  Attr PSize  PFree
  /dev/sdb   rootvg lvm2 a--  19.97g  6.75g
  /dev/sdc          lvm2 ---   4.00g  4.00g
  /dev/sdd          lvm2 ---   4.00g  4.00g
  /dev/sdg   vgtest lvm2 a--  16.00g 10.00g
# vgextend vgtest /dev/sdc /dev/sdd
  Volume group "vgtest" successfully extended

Create mirror chain for existing LV with desired parameters:

# lvconvert -m1 --stripes 2 /dev/vgtest/data /dev/sdc /dev/sdd
  Using default stripesize 64.00 KiB
  vgtest/data: Converted: 0.0%
  vgtest/data: Converted: 30.2%
  vgtest/data: Converted: 59.4%
  vgtest/data: Converted: 100.0%
# lvs -a -o +devices | grep -v rootvg
  LV              VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log       Cpy%Sync Convert Devices
  data            vgtest mwi-aom---   6.00g                                data_mlog 100.00           data_mimage_0(0),data_mimage_1(0)
  [data_mimage_0] vgtest iwi-aom---   6.00g                                                           /dev/sdg(0)
  [data_mimage_1] vgtest iwi-aom---   6.00g                                                           /dev/sdc(0),/dev/sdd(0)
  [data_mlog]     vgtest lwi-aom---   4.00m                                                           /dev/sdd(768)
# pvdisplay -m /dev/sdd
  --- Physical volume ---
  PV Name               /dev/sdd
  VG Name               vgtest
  PV Size               4.00 GiB / not usable 4.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              1023
  Free PE               254
  Allocated PE          769
  PV UUID               1ucJ4r-lc9N-BcHU-jOjU-PWg0-h3xI-q8szeP

  --- Physical Segments ---
  Physical extent 0 to 767:
    Logical volume      /dev/vgtest/data_mimage_1
    Logical extents     0 to 1535
  Physical extent 768 to 768:
    Logical volume      /dev/vgtest/data_mlog
    Logical extents     0 to 0
  Physical extent 769 to 1022:
    FREE

Break mirror removing desired chain:

# lvconvert -m0 /dev/vgtest/data /dev/sdg
  Logical volume data converted.
# lvs -a -o +devices | grep -v rootvg
  LV    VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert Devices
  data  vgtest -wi-ao----   6.00g                                                     /dev/sdc(0),/dev/sdd(0)

Remove original PV from VG, unconfigure SCSI device, then unmap LUN.


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Updated on Mon Jul 20 11:56:27 IDT 2015 by Oleg Volkov More documentations here