Known issues with Linux VOB hosts accessing VOB storage on NAS over NFS

Preventive Service Planning


This technote provides information about known issues with Linux VOB hosts (both SUSE and Red Hat) accessing VOB database storage over Network File System ( NFS).


Various defects in the Linux implementation of the NFS client can cause VOBs to become inaccessible (worst case) or cause significant performance degradations (best case).
The following versions of Linux are known to work correctly (as of June 2012) when VOBs are hosted on a Network Attached Storage (NAS):

  • Red Hat Enterprise 4 Update 8
  • Red Hat Enterprise 5 Update 3
  • Red Hat Enterprise 5 Update 5 with Advisory RHSA-2010:0504-1
  • SUSE 10 with all Updates

  1. Use one of the Linux versions listed above.
  2. Do not use NFS to mount the VOB database storage.
  3. Version introduces a new alternate configuration which involves moving the almd files (used for VOB database concurrency control) to local disk storage on the VOB server, that reduces the impact of the NFS defects on ClearCase.
    Review technote 1637860 for more details on this solution.
  4. Version added the new alternate configuration described above..


If you choose to avoid using NFS for VOB database storage (workaround "b" above), consider the following:
  • Split the VOB database storage from the VOB pools and keep the VOB pools on the NAS.
  • Use fiber channel or iSCSI to connect the VOB host to the VOB database storage on the NAS.

This configuration not only side steps potential NFS defects but also improves and optimizes the performance of VOB hosts.

Refer to the Rational ClearCase System Requirements List for additional information about supported platforms.

Related information

Server processes consume 100% CPU
Server processes may not terminate
ClearCase on NetApp Data ONTAP in Cluster-Mode

Cross reference information
Segment Product Component Platform Version Edition
Software Development Rational ClearCase VOB Linux

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Rational ClearCase

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7.0,,,,,,,,,, 7.0.1,,,,,,,,,,,,, 7.1,,, 7.1.1,,,,,,,,,, 7.1.2,,,,,,,,,,,, 8.0,,,,,,,, 8.0.1,

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