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Performance improvements consume additional VOB host memory

Question & Answer


What are the memory consumption implications of the performance improvements?


In this release, commands that access all VOBs mounted at the VOB mount point execute substantially faster than they did in previous releases. Examples of such commands are:

  • ls -l /vobs
  • ls -F /vobs
where /vobs is the VOB mount point. The change involves allowing a vobrpc_server process associated with every VOB on a VOB host to persist indefinitely. Where activity against a VOB results in several vobrpc_server processes running for a VOB, only one such process persists indefinitely; the supplementary vobrpc_servers exit when they are idle, as in earlier releases.

However, each long-lived vobrpc_server process consumes about 2 MB of private memory (its address space will be larger, about 9 MB, because of its use of shared libraries). Thus on VOB hosts where, for example, 500 VOBs are mounted, 1 GB of additional memory may be consumed by all such vobrpc_server processes.

Before migrating to a version of ClearCase that provides this performance improvement, estimate and acquire sufficient additional memory for your VOB hosts to avoid performance degradations.

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Document Information

Modified date:
24 October 2018