Online resize of multipath device in RHEL 6

Task: On RHEL 6 64-bit, perform online resize of filesystem /journal from 50GB to 100GB. That filesystem is part of multipath device brc001_journal_pv.

HOWTO:

In this post we are going to resize multipath device brc001_journal_pv with running IO operations.  OS used is RHEL 6.2 64-bit. Remember, if you want to actually decrease size of volume, you cannot do that online, you have to unmount relevant filesystem, resize filesystem, resize lv/vg/pv and finally resize disk on array. But today we are going to increase size, so its easier.

What are relevant paths of device? 

# multipath -ll

brc001_journal_pv (36000d310003582000000000000000026) dm-1 COMPELNT,Compellent Vol

size=50G features='1 queue_if_no_path' hwhandler='0' wp=rw

`-+- policy='round-robin 0' prio=1 status=active

  |- 2:0:5:2 sdh 8:112 active ready running

  `- 1:0:7:2 sdp 8:240 active ready running

.

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Multipath device brc001_journal_pv has paths sdh a sdp.

1.      First we increase size of LUN on disk array. Every disk array has different guide, so please refer to documentation of your disk array.

2.     Second we will rescan relevant paths and multipath device

echo 1 > /sys/block/sdh/device/rescan

echo 1 > /sys/block/sdp/device/rescan

multipathd -k"resize map brc001_journal_pv"

# multipath -ll

brc001_journal_pv (36000d310003582000000000000000026) dm-1 COMPELNT,Compellent Vol

size=100G features='1 queue_if_no_path' hwhandler='0' wp=rw

`-+- policy='round-robin 0' prio=1 status=active

  |- 2:0:5:2 sdh 8:112 active ready running

  `- 1:0:7:2 sdp 8:240 active ready running

3.     Resize physical volume

# pvresize /dev/mapper/brc001_journal_pv

  Physical volume "/dev/mapper/brc001_journal_pv" changed

  1 physical volume(s) resized / 0 physical volume(s) not resized

# pvs /dev/mapper/brc001_journal_pv

  PV                            VG                Fmt  Attr PSize   PFree

  /dev/mapper/brc001_journal_pv brc001_journal_vg lvm2 a--  100.00g    0

4.     Resize logical volume

# lvresize -l 100%VG /dev/mapper/brc001_journal_vg-journal_lv

  Extending logical volume journal_lv to 100.00 GiB                     

  Logical volume journal_lv successfully resized

# lvs brc001_journal_vg

  LV         VG                Attr   LSize   Origin Snap%  Move Log Copy%  Convert

  journal_lv brc001_journal_vg -wi-ao 100.00g

5.     Resize filesystem and we are done!

# resize2fs /dev/mapper/brc001_journal_vg-journal_lv

resize2fs 1.41.12 (17-May-2010)

Filesystem at /dev/mapper/brc001_journal_vg-journal_lv is mounted on /journal; on-line resizing required

old desc_blocks = 4, new_desc_blocks = 7

Performing an on-line resize of /dev/mapper/brc001_journal_vg-journal_lv to 26213376 (4k) blocks.

The filesystem on /dev/mapper/brc001_journal_vg-journal_lv is now 26213376 blocks long.

# df -h /journal/

Filesystem            Size  Used Avail Use% Mounted on

/dev/mapper/brc001_journal_vg-journal_lv

                       99G   18G   82G  18% /journal