Page life expectancy

  • I'm getting page life expectancy low alert. Threshold is set to 300. Any idea what to look for and how to correct this?

  • Who says it needs correcting? PLE < 300 is not necessarily a bad thing. It could be that your system just has a highly volatile memory use. I'd want to see a lot more information before I started worrying. You should look at wait statistics to see what's causing the system to slow down. Here's an article [/url]I wrote on a few things you can look at on a system to get a quick idea where the real problems might be.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
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  • Well firstly start by fixing that silly threshold value. 300 is insanely low for a sustained value for PLE, unless you still have a server with < 4GB memory

    Chapter 4: http://www.red-gate.com/community/books/accidental-dba

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • IMHO any PLE value smaller than 1,000, let alone 300, is a serious issue if it stays there and never increases. We try and maintain 10,000 or better on all of our SQL Servers (650+ and growing). We do have one old problem child that we address when PLE drops below 1,000 (it is WIndows 2003 R2 32 bit with SQL 2005 - it is on the fast track for upgrade to 2012 since we are capped at 32 GB of RAM and need 48 GB.

    In perfmon I would look at Reserved Pages, Target Pages, Stolen Pages initially.

    If Target Pages is consistantly significantly greater (at lest 10-20+%) than Reserved Pages you probably need to add more RAM (at a minimum look for extremely bad and or poorly performing queries).

    If Stolen Pages is significant, say 100's of MB to multiple GB, for an extended period of time, say hours to days, compare that value to the current pagefile usage then you'll need to again, add more RAM (at a minimum look for extremely bad and or poorly performing queries).

    Mind you these are 'diagnosis at 30,000 feet steps'.

    RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."

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