I have a server with a multipath (example) and without LVM. (mpathb -> 5 Tb).

mpathb (360002ac00000000000003af40000af6b) dm-3 3PARdata,VV
size=5.0T features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=0 status=active
|- 1:0:1:0 sdc 8:32 active undef running
|- 1:0:0:0 sdb 8:16 active undef running
|- 2:0:0:0 sde 8:64 active undef running
`- 2:0:1:0 sdd 8:48 active undef running

And the disk mounted.

/dev/mapper/mpathbp1              /data  (5.0 Tb).

I will need to increase this disk, How do that?

Increase at Storage the LUN (From: 5 Tb -> To: 7 Tb) - example.
Execute echo 1 > /sys/block/path_device/device/rescan (for all paths).
Execute multipathd -k 'resize map mpathb'
Execute resize2fs /dev/mpathbp1

This procedure its correct?

I have just one partition.

Would be partprobe where? Partprobe /dev/mapper/mparha?

Could explain in details?

1 Answer 1


Note: to avoid a multipath bug in resizing multipathed disks/partitions, your kernel version should be kernel-3.10.0-862.el7 or later.

After resizing the multipath map, the system is now seeing the multipathed disk with the new size (7 TB), but the partition table on the device still specifies the old size (5 TB) for the partition.

You’ll need two more steps:

  1. Edit the partition table to extend the partition (fdisk /dev/mapper/mpathb)

  2. Run partprobe -s or kpartx -u /dev/mapper/mpathb to make the partition changes effective before you can extend the filesystem. You should now see the new size (in bytes) with blockdev --getsize64 /dev/mapper/mpathb1.

After these extra steps, you can resize the filesystem.

  • Edited. Sorry about earlier terse answer, I was on mobile and could not check my notes...
    – telcoM
    May 12, 2020 at 8:00

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