High Load on Cassandra

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Revision as of 17:06, 29 November 2010 by Cocodude (talk | contribs)
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High loan on Cassandra (the main domU on node00004) can be caused by tasks that run during the night (around 3 - 5am) or by an issue with the VPS. High load at 3-5am can usually be ignored, but other issues need to be examined as soon as possible.

  • If you can log in to Cassandra (the domU), examine the currently running processes by typing ps | aux and top.
  • Feel free to restart any high-load processes by usign /etc/init.d/XXX restart as required. These are often apache or pure-ftpd.
  • There will often be a load of at least 4 because of the distributed.net process that runs across all four cores.
  • If you cannot log in directly to Cassandra, log in to the dom0 as root and type xm console xen01. You should then be at the Emohawk console and can run commands from there.
  • Follow instructions at Cassandra (domU) is not responding as expected

If an issue cannot be put down to Cassandra itself, it's worth seeing what others are doing on the dom0.

  • Log in as root on the dom0 and type iostat -k -d -N 1 100. This will view the I/O status each second for the next 100 seconds.
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