SQL Server Performance

Finding Specs on SAS - SATA - SCSI

Discussion in 'SQL Server 2005 Performance Tuning for Hardware' started by DBADave, May 17, 2007.

  1. DBADave New Member

    I'm trying to do a crash course on SAS technology and want to see a chart or paper on performance comparisons. I always request 15k SCSI drives for our database servers, but for a new project we purchased 10k SAS for our QA environment despite me requesting 15k SAS. The production environment is on a SAN and we wanted to reduce costs a bit for QA so that's why SAS drives were purchased. However, we need to match production performance as closely as possible with our drives so stress testing can be performed. The problem is I don't know how 10k SAS compares with 15k SCSI or EMC SAN drives. A nice chart comparing the types of disks we be nice to reference.

    Thanks, Dave
  2. joechang New Member

    unless you are just swimming in money,
    it is reasonable to make adjustments to save money on the QA system

    SAS has better sequential BW than SCSI or FC
    random stays the same

    so 15K has 50% better random IO than 10K

    if you have 28 10K drives in QA,
    and prod has 28K 15 drives
    then prod should support 50% more random IO

    SAS will beat the SAN by a wide margin on sequential if you configured it right
    if not, then oh well
  3. DBADave New Member

    Thanks Joe. What about comparing SAS drives to Fiber Channel drives on the SAN? Would 10k SAS drives be a big drop-off in performance from Fiber Channel? I'm trying to get a feel for how stress testing results on QA (SAS) will translate to production (SAN).

    Production
    Data - SAN/Fiber Channel - RAID 10 (Dedicated controller)
    Logs - SAN/Fiber Channel - RAID 10 (Dedicated controller)
    Tempdb - SAN/Fiber Channel - RAID 10 (Dedicated Controller)

    QA
    Data - SAS 10k - RAID 10 (Dedicated controller)
    Logs - SAS 10k - RAID 10 (Dedicated controller)
    Tempdb - SAS 10k - RAID 10 (Dedicated controller)

    Dave
  4. joechang New Member

    SAS is 3Gbit/sec, and you are most likely using a x4 wide SAS connector,
    meaning 12Gbit/s

    FC is either 2Gbit/sec for pre-2006/07
    or possibly 4Gbit/sec for very new models

    run my scripts in the top post

    for get RAID levels, how many disks behind each, and are the disks shared or dedicated
  5. CG2000 New Member

    Seagate and Adaptec have brochures(specs) and whitepapers available. You can usually get a sales engineer by calling customer support at Seagate in North America - or at least you could a year ago when I did it last (or go through your h/w vendor).

    SAS is quicker in bursty read/writes and sustained throughput - not as flexible in overall config as FC especially with larger raid implementations. Those FC fabric switches are bags of coin though.

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