SQL Server Performance

How to Carve a SAN

Discussion in 'Performance Tuning for Hardware Configurations' started by kyang, Aug 7, 2006.

  1. kyang New Member

    Hello Guys,

    We are going to host 12 large DB, 150GB + each, they will be hosting on a SAN that contain 9 VLUN which make up of 36 * 150GB disk drives. For Disk I/O subsystem performance, would it help if we create 72 LUNs and put each type of data files on each LUN. For example
    LUN1 = VLUN1, VLUN3, VLUN5, VLUN8 for Reference Datafile
    LUN2 = VLUN3, VLUN4, VLUN7, VLUN1 for Indexes Datafile
    LUN3 = VLUN2, VLUN8, VLUN0, VLUN1 for App Type A Datafile
    … for App Type B Datafile
    LUN72 = VLUN0, VLUN2, VLUN3, VLUN6, VLUN5 for historical Datafile

    any help will be highly appreciated.


  2. Luis Martin Moderator

    I've moved to relevant forum.

    Luis Martin

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  3. joechang New Member

    the VLUN is very bad for performance critical databases
    it is also absolutely essential for each high volume database to have dedicated physical disks for the log. normally 2 disks in RAID 1 is sufficient, however SAN drives generally have poor sequential performance, so 4-6 disks for the log is better. figure 10MB/sec for each pair, then determine how many disks you need for each

    multiple databases can share disks for the data file, but low latency transaction db should share one pool, while DW apps should share another.

    the other criteria is that the data files should be able to sustain > 300MB/sec, preferably >700MB/sec, test this with a table scan returning few rows, this is so that a large query does not shut down transaction processing capability.

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