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    Slow performance: checkpoint waits, ZFS pools

    • Article Type: General
    • Product: Aleph
    • Product Version: 20

    We are experiencing extremely slow performance on our production Aleph server. The problem has been with us for over three weeks. It became significantly worse over the weekend - March 3-4 - and continued into today. Our DBAs are attempting to resolve the problem, and have opened a Level 2 service request with Oracle. The database (and Aleph application) was restarted this morning at 09:03 local time.

    On the database side we are seeing an extremely high number and duration of "enq: KO - fast start checkpoint" waits.

    [From site:] On the Aleph (Solaris) server, one of the administrators noted that ZFS pools can perform poorly for things like database logging activity if they become more than 80% full. There is a technical explanation of this here:
    We have been running several databases servers on ZFS up to now and had never seen this problem before. I requested additional storage (on the Aleph server) and the checkpoint waits subsided.

    • Article last edited: 10/8/2013