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>