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Recommended RAID setup for new installation

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  • Recommended RAID setup for new installation

    Hi all

    I am looking for feedback on setting up a new pair of servers. I will be running a pair of machines, using DRBD failover, and pacemaker.

    The machines they are replacing have the following usage patterns:

    * They generate about 2 Gb binary logs per day.
    * About 3 MB/s of data leaves the network cards
    * About 0.4 MB/s arrives on the network cards
    * About 800 select/sec
    * About 180 Update/sec
    * Innodb tables currently take up about 100G

    With those stats in mind, what would be the best way of setting up the hard drives (There are 8 300Gb drives per server). I am leaning towards

    2x 300Gb (Raid 1) for OS
    2x 300Gb (Raid 1) for binlogs
    2x 300Gb (Raid 1) for data
    2x 300Gb as hot spare

    The binlogs and data would be mirrored via drbd
    My issue with this is that out of 16 300 Gb drives, I end up with 300Gb usable storage for the database.

    Alternatively, I could go with
    2x 300Gb (Raid 1) for OS and binlogs
    4x 300Gb (Raid 10) for data
    2x 300Gb as hot spare (or add them above to have 6 drive raid 10 for data with no hot spare)


    Any suggestions/comments?

  • #2
    I wouldn't bother putting the binlogs on their own set of drives. I'd just create a 2-disk RAID1 for the operating system and a 6-disk RAID10 for the data and logs.

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    • #3
      I've always felt that having the binlogs on separate physical disks is good for performance due to physical limitations with fsyncs/sec, and contention for bandwidth.

      I realise that the stats I gave are a bit low, but I am planning for growth of at least 4x over the next year.

      In general, are you recommending keeping logs and data on the same drives, or just in my situation?

      Comment


      • #4
        If you have 20 disks, dedicating 2 of them to the trivial binlog workload is a good idea. If you have a handful of disks, all you're doing is starving the place that needs IO capacity the most: the database itself. The fsyncs/sec are not improved by having many disks. That's what a battery-backed write cache on the RAID controller does for you, and it doesn't matter how many disks are behind the cache.

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