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3 replies Latest Post - ‏2009-08-08T14:41:55Z by musthalie
musthalie
musthalie
3 Posts
ACCEPTED ANSWER

Pinned topic Recommended Block Size On Disk Array

‏2008-11-10T10:18:20Z |
1) What is recommended block size needs to be configured in a disk array?
2) How to tune the block size parameter in Informix IDS 11.0?
Updated on 2009-08-08T14:41:55Z at 2009-08-08T14:41:55Z by musthalie
  • dkremen
    dkremen
    7 Posts
    ACCEPTED ANSWER

    Re: Recommended Block Size On Disk Array

    ‏2008-11-10T17:02:54Z  in response to musthalie
    Which OS, IDS, ...?
    • dkremen
      dkremen
      7 Posts
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      Re: Recommended Block Size On Disk Array

      ‏2008-11-10T17:18:00Z  in response to dkremen
      Oops, pressed submit too fast...

      In general, you want to spread your load as evenly as possible.
      Use as many disks as you can (you don't mention if these are internal disks, SAN maybe, ...). Preferably in RAID10. Block size should not be too small, otherwise you can generate too much IO request during peak times. Consider that today's disk are supposed to max out around 200 to 300 IO requests per second.

      This is a bit vague topic (at least for me). What I've learned thus far (and I might be completely wrong, all corrections welcome) is Informix will read/write either in one page (2K/4K, depending on OS) or in 8 pages (big buffers).

      Next, it depends if you're on file system or raw. File system implementation might decide to merge some blocks so you may end up with bigger IO block sizes. On raw it should stay 1pg/8pg.

      Also, you have to decide for what you're optimising: everyday or peak time. We do the latter so we set block size to 8 pages on our SAN disk volumes. It's a trade-off: we are (probably) wasting 7 pages out of every 8 during normal load, but during high load we are not generating excessive number of IOs.

      Hopefully someone else will also help to demystify this...

      Cheers

      Davorin
    • musthalie
      musthalie
      3 Posts
      ACCEPTED ANSWER

      IDS 11.5 Vs Oracle RAC

      ‏2009-08-08T14:41:55Z  in response to dkremen
      Hi,

      In IDS 11.5 "All types of secondary servers can be configured to perform write operations" it looks like not similar to Oracel RAC (comparing with ASM etc.)! Any one who have experience in 11.5 cluster Active/Active configuration?

      Thanks
      Musthalie