Server support blog

Problem: You have LVM logical volume configured to hold a lot of data but at some point you ran out of space – you want to expand the logical volume space by adding more disks to the system.

Prerequisites: It would be very wise to use XFS filesystem on the large logical volume from the very beginning – aside from performance improvement it has 2 very important advantages:

• Scheduled or recovery disk check is very fast, regardless of disk size (on disks bigger then 1Tb disk scan on boot takes considerable time – EXT3 takes hours to check)
• You can expand filesystem while it’s mounted and “live” (in fact you have to have it mounted to do so), and this operation is quick and does not put your existing data in the harm way (when you are extending 20Tb logical volume to 40Tb because it’s almost full loosing all this data is not an option).

Now, down to business. Assumed setup:

• Existing logical volume home on volume group vg00 with physical volume /dev/sda2, mounted under /home and formatted with XFS filesystem
• The new disk being added is /dev/sdb1

1. Create new physical volume and verify
   
   Shell

   pvcreate /dev/sdb1 pvdisplay --- Physical volume --- PV Name /dev/sdb1 VG Name vg00 PV Size 1.82 TB / not usable 4.09 MB Allocatable yes PE Size (KByte) 4096 Total PE 476156 Free PE 476156 Allocated PE 0 PV UUID yz3NdE-VgQo-AMbq-76Kk-lY7d-PhUZ-kPrwhP --- Physical volume --- PV Name /dev/sda2 VG Name vg00 PV Size 1.77 TB / not usable 2.69 MB Allocatable yes (but full) PE Size (KByte) 4096 Total PE 463131 Free PE 0 Allocated PE 463131 PV UUID 9vpgT4-nvz4-DtfM-kXn7-TXmO-3bBd-fnomtC

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

   pvcreate /dev/sdb1 pvdisplay   --- Physical volume ---   PV Name               /dev/sdb1   VG Name               vg00   PV Size               1.82 TB / not usable 4.09 MB   Allocatable           yes   PE Size (KByte)       4096   Total PE              476156   Free PE               476156   Allocated PE          0   PV UUID               yz3NdE-VgQo-AMbq-76Kk-lY7d-PhUZ-kPrwhP      --- Physical volume ---   PV Name               /dev/sda2   VG Name               vg00   PV Size               1.77 TB / not usable 2.69 MB   Allocatable           yes (but full)   PE Size (KByte)       4096   Total PE              463131   Free PE               0   Allocated PE          463131   PV UUID               9vpgT4-nvz4-DtfM-kXn7-TXmO-3bBd-fnomtC

2. Add new physical volume to the existing volume group and verify
   
   Shell

   vgextend vg00 /dev/sdb1 vgdisplay --- Volume group --- VG Name vg00 System ID Format lvm2 Metadata Areas 2 Metadata Sequence No 4 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 1 Max PV 0 Cur PV 2 Act PV 2 VG Size 3.58 TB PE Size 4.00 MB Total PE 939287 Alloc PE / Size 469643 / 1.79 TB Free PE / Size 469643 / 1.79 VG UUID Ve9RLp-aEQM-ji1X-WCMh-9tP9-ZMOx-OVxYcQ

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

   vgextend vg00 /dev/sdb1 vgdisplay   --- Volume group ---   VG Name               vg00   System ID               Format                lvm2   Metadata Areas        2   Metadata Sequence No  4   VG Access             read/write   VG Status             resizable   MAX LV                0   Cur LV                1   Open LV               1   Max PV                0   Cur PV                2   Act PV                2   VG Size               3.58 TB   PE Size               4.00 MB   Total PE              939287   Alloc PE / Size       469643 / 1.79 TB   Free  PE / Size       469643 / 1.79     VG UUID               Ve9RLp-aEQM-ji1X-WCMh-9tP9-ZMOx-OVxYcQ

3. Expand logical volume and verify
   
   Shell

   lvextend -l +100%FREE /dev/vg00/home lvdisplay --- Logical volume --- LV Name /dev/vg00/home VG Name vg00 LV UUID Ysewsi-Ekdm-ug3M-Dcmd-sJGO-owxC-qNsdBu LV Write Access read/write LV Status available # open 1 LV Size 3.58 TB Current LE 939287 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

   lvextend -l +100%FREE /dev/vg00/home lvdisplay         --- Logical volume ---   LV Name                /dev/vg00/home   VG Name                vg00   LV UUID                Ysewsi-Ekdm-ug3M-Dcmd-sJGO-owxC-qNsdBu   LV Write Access        read/write   LV Status              available   # open                 1   LV Size                3.58 TB   Current LE             939287   Segments               2   Allocation             inherit   Read ahead sectors     auto   - currently set to     256   Block device           253:0

4. Increase the filesystem size to the full size of the logical volume
   
   Shell

   xfs_growfs /home meta-data=/dev/vg00/home isize=256 agcount=64, agsize=15236992 blks = sectsz=512 attr=0 data = bsize=4096 blocks=961829888, imaxpct=25 = sunit=0 swidth=0 blks, unwritten=1 naming =version 2 bsize=4096 log =internal bsize=4096 blocks=32768, version=1 = sectsz=512 sunit=0 blks, lazy-count=0 realtime =none extsz=4096 blocks=0, rtextents=0

   1 2 3 4 5 6 7 8 9

   xfs_growfs /home meta-data=/dev/vg00/home         isize=256    agcount=64, agsize=15236992 blks          =                       sectsz=512   attr=0 data     =                       bsize=4096   blocks=961829888, imaxpct=25          =                       sunit=0      swidth=0 blks, unwritten=1 naming   =version 2              bsize=4096   log      =internal               bsize=4096   blocks=32768, version=1          =                       sectsz=512   sunit=0 blks, lazy-count=0 realtime =none                   extsz=4096   blocks=0, rtextents=0

You are done – enjoy your bigger logical disk.