Topic
  • 3 replies
  • Latest Post - ‏2009-08-08T14:41:55Z by musthalie
musthalie
musthalie
3 Posts

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

    Re: Recommended Block Size On Disk Array

    ‏2008-11-10T17:02:54Z  
    Which OS, IDS, ...?
  • dkremen
    dkremen
    7 Posts

    Re: Recommended Block Size On Disk Array

    ‏2008-11-10T17:18:00Z  
    • dkremen
    • ‏2008-11-10T17:02:54Z
    Which OS, IDS, ...?
    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

    IDS 11.5 Vs Oracle RAC

    ‏2009-08-08T14:41:55Z  
    • dkremen
    • ‏2008-11-10T17:02:54Z
    Which OS, IDS, ...?
    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