LVM: Howto increase the size of a filesystem on-the-fly

Oops, that is not good :-(
/dev/mapper/database_vg-db_vol 690G 655G 12K 100% <the SHADOW database filesystem>
This happened at 4am. What can you do in case that this happens to you? Praying is always a solution. The better solution is checking your free physical space.

[root@mymachine ~]# pvs
  Found duplicate PV fFza0t96dLLdVGnklCVRvIFacmJ1Kd4I: using /dev/sdc not /dev/sdq
  PV             VG           Fmt  Attr PSize   PFree
  /dev/emcpowera audit_vg     lvm2 a--    2.00t  548.00g
  /dev/emcpowerb logs_vg      lvm2 a--  500.00g 1020.00m
  /dev/emcpowerc database_vg  lvm2 a--    1.46t  600.00g
  /dev/sda3      vg_scloshad2 lvm2 a--  127.93g       0

Phew 600GB available. So let’s see how the logical drive can be extended by 200GB.

[root@mymachine ~]# lvextend -L +200G /dev/mapper/database_vg-db_vol /dev/emcpowerc
  Found duplicate PV fFza0t96dLLdVGnklCVRvIFacmJ1Kd4I: using /dev/sdc not /dev/sdq
  Extending logical volume db_vol to 900.00 GiB
  Logical volume db_vol successfully resized

That was quick. Now we have to resize the filesystem and we can do this while the database is still up and running :-)

[root@mymachine ~]# resize2fs /dev/mapper/database_vg-db_vol
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/database_vg-db_vol is mounted on /trak/sclo/SHADOW/db/data; on-line resizing required
old desc_blocks = 44, new_desc_blocks = 57
Performing an on-line resize of /dev/mapper/database_vg-db_vol to 235929600 (4k) blocks.
The filesystem on /dev/mapper/database_vg-db_vol is now 235929600 blocks long.

…. 5 minutes later.
/dev/mapper/database_vg-db_vol 886G 655G 187G 78% /trak/sclo/SHADOW/db/data

It is quite possible that you already used up all the physical space for your virtual drives. In that case you can easily add more physical disks or LUNs to the disk group in using the ‘vgextend’ command. E.g. vgextend database_vg /dev/emcpowerd

About Juergen Caris

I am 54yo, MSc(Dist) and BSc in Computer Science, German and working as a Senior Server Engineer for the NHS Lothian. I am responsible for the patient management system, called TrakCare. I am a UNIX/Linux guy, working in this sector for more than 20 years now. I am also interested in robotics, microprocessors, system monitoring, Home automation and programming.
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