4.4. Storage and Filesystems

The NFSv4 server in Red Hat Enterprise Linux 6 currently allows clients to mount using UDP and advertises NFSv4 over UDP with rpcbind. However, this configuration is not supported by Red Hat and violates the RFC 3530 standard.

If a device-mapper-multipath device is still open, but all of the attached paths have been lost, the device is unable to create a new table with no paths. Consequently, the following unusual output may be returned from the multipath -ll output command:

mpatha (3600a59a0000c2fd0003079284c122fec) dm-0,
size=2.0G hwhandler='0'
|-+- policy='round-robin 0' prio=0 status=enabled
| `- #:#:#:# -   #:#  failed faulty running
`-+- policy='round-robin 0' prio=0 status=enabled
  |- #:#:#:# -   #:#  failed faulty running
  `- #:#:#:# -   #:#  failed faulty running

Output of this type indicates that there are no paths to the device. The erroneous lines in the output preceded by the string #:#:#:# will be removed in a future release.

dracut currently only supports one FiberChannel over Ethernet (FCoE) connection to be used to boot from the root device. Consequently, booting from a root device that spans multiple FCoE devices (e.g. using RAID, LVM or similar techniques) is not possible.

pvmove cannot currently be used to move mirror devices. However, it is possible to move mirror devices by issuing a sequence of two commands. For mirror images, add a new image on the destination PV and then remove the mirror image on the source PV.

$> lvconvert -m +1 <vg/lv> <new PV>
$> lvconvert -m -1 <vg/lv> <old PV>

Mirror logs can be handled in a similar fashion:

$> lvconvert --mirrorlog core <vg/lv>
$> lvconvert --mirrorlog disk <vg/lv> <new PV>

or
$> lvconvert --mirrorlog mirrored <vg/lv> <new PV>
$> lvconvert --mirrorlog   disk   <vg/lv> <old PV>