SQL Server Performance

DL580G3 L3 cache and database performance

Discussion in 'Performance Tuning for Hardware Configurations' started by obrp, Mar 31, 2005.

  1. obrp New Member

    Hello,

    We are looking for dl580 as a new hardware for our sqlserver2000 application (mix OLTP+Queries). Options are:

    3.60 w 1MB L2
    3.33 w 1MB L2 + 8MB L3 (but +3K$)

    How L3 cache will affect performance. Is it worth of getting less Ghz's but with more L3?

    Thanks in advance,
    Ed
  2. joechang New Member

    the big cache improves oltp type queries, ie, small row count operations.
    it does not do much for big DW queries,
    it does improve scaling from 1 CPU to 2 to 4.
    hence, there may not be much difference (not accounting for frequency difference) in tests that run 1 CPU, but there will be more at 2 and even more at 4
    you could always buy the 580 with 2 1M L2 only CPUs,
    if CPU load is heavy, then replace them with 4 CPUs with the 8M L3.
  3. obrp New Member

    2joechang<br /><br />Thanks for the answer. Hard question, since the difference between 2 servers, with L3 cache and without - is more than 15K$!<br />For me is not clear, how much scaling will be improved, is it 1%, 10%? What is that performance gain in case of my apps? This things needs to be tested, but in my case this is allmost impossible. So, this question is about argument weighing &gt;15K$ <img src='/community/emoticons/emotion-1.gif' alt=':)' /><br /><br />TIA,<br />Ed<br />
  4. joechang New Member

    it does depend on the app, but with all 4 CPU sockets populated, i would say it is reasonably to use 15% for these calculations.
    i think it will be less for DW apps, but possibly more for OLTP queries.
    also, my assumption of 15% is based on the previous Xeon MP line, comparing
    1M->2M->4M when all cache levels were equivalent.

    perhaps the big thing to factor is the value of the application, if you are running SQL Std Ed ($3K/CPU?) and a low cost app, the 15% might not be worth it.
    but if you are running Ent Ed ($16K/CPU) and an expensive, app, the extra 15% might be very much worth the higher cost
  5. derrickleggett New Member

    What are you running on now? What does your processor performance look like? What is the latency and complexity of your requests? What kind of growth are you expecting on the new hardware? What kind of environment is it? Are there other apps running?

    There's no sense in buying it if you won't use it. Like Joe said though, if this is a complex app that uses the processor heavily, than it would be well worth the cost.

    On the DW apps, it depends on the nature of the analytics processing, and where you're actually doing that processing. They can be very processor intensive, depending on where this particular piece lives.

    There are a lot of consideration here. I would definitely answer the above questions though, and see if we can pinpoint something more specific.

    MeanOldDBA
    derrickleggett@hotmail.com

    When life gives you a lemon, fire the DBA.

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