Red Hat Bugzilla – Bug 338481
fdisk rescan fails on /dev/mapper multipath device
Last modified: 2010-01-11 21:31:17 EST
Description of problem:
Writing a new partition table to a multipath lun fails rescanning the parition table
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Map a new LUN via fibre channel through mpio
2. Fdisk the new /dev/mapper device
3. Create partition 1 spanning from cylinder 1 to the end of the disk:
# fdisk /dev/mapper/360a9800068714342575a454155643943
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): Command action
p primary partition (1-4)
Partition number (1-4): First cylinder (1-1019, default 1): Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1019, default 1019): Using default value 1019
Command (m for help): The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table.
The new table will be used at the next reboot.
Kernel fails to reload partition table and requires reboot
ioctl should force partition rescan and create /dev/mapper and /dev/mpath device nodes for the new
There are no plans to make this work for RHEL 4. There is a possibility that
this feature to make it into RHEL 5. See bz #156609 for more details.
There are two ways to work around this. The obvious one is to run
# multipath -f <device_you_want_to_parition>
# fdisk <one_of_the_underlying_devices>
The other method is to use LVM on top the multipathed device. This will allow
you to "repartition" your device without bringing the multipath device down.