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  1. #1
    Join Date
    Jul 2003
    Location
    Chicago, IL
    Posts
    2

    Unanswered: Performance degradation writing to a SAN / building a cube

    Is anyone aware of performance degradation writing to a SAN over fibre optic network? We r using SQL Server 2000 (Enterprise version) with Compaq Proliant DL580 G2, writing to Compaq SAN. Is any network tuning needed? A gigabit ethernet card pushes the data over to the SAN.

    Also, we r taking about 37 hours building a cube for a database barely 15GB. Database is shipped by Microsoft and is used by their product Microsoft Proect Server. So, database level tuning is out of question.

    Any help would greatly be appreciated.

    Thanx in advance,

    Bhushan

  2. #2
    Join Date
    Dec 2002
    Posts
    63
    You should try the basic performance tuning practices to find out where your bottle neck is. Here are a few we use to help us troubleshoot our san...

    *check CPU utilization on the sql node -- this could be caused by a lot of things
    *Check disk idle time -- if your disk is below 20% idle, then you are spindle bound.
    *check disk queue length. -- if the disk queue is higher than twice the number of disks in your raid array, then you have a problem. High disk queue could also be a problem with the NIC. it is possible it cant send data as fast as the cable and disks can handle it.
    *check memory usage. -- if you are trying to cache everything and the pc starts paging, this will kill performance
    *check your query plans (not sure if that is possible, but if it is running poorly it can make a huge difference.)
    *check your network traffic between the pc and the san. are you seeing any collisions?

    basically it comes down to finding the bottleneck and then fixing it.

  3. #3
    Join Date
    Jul 2003
    Location
    Chicago, IL
    Posts
    2
    Originally posted by Pigeon
    You should try the basic performance tuning practices to find out where your bottle neck is. Here are a few we use to help us troubleshoot our san...

    *check CPU utilization on the sql node -- this could be caused by a lot of things
    *Check disk idle time -- if your disk is below 20% idle, then you are spindle bound.
    *check disk queue length. -- if the disk queue is higher than twice the number of disks in your raid array, then you have a problem. High disk queue could also be a problem with the NIC. it is possible it cant send data as fast as the cable and disks can handle it.
    *check memory usage. -- if you are trying to cache everything and the pc starts paging, this will kill performance
    *check your query plans (not sure if that is possible, but if it is running poorly it can make a huge difference.)
    *check your network traffic between the pc and the san. are you seeing any collisions?

    basically it comes down to finding the bottleneck and then fixing it.
    Thanx a lot, Pigeon. I did check the Queue length originally; but was told by Compaq that the Queue length reported by Windows 2000 (for Compaq hardware) is not reliable for various reasons.

    Anway! I personally think NIC card is slow and thats why I am seeing NETWORKIOWAIT within SQL Server. Just wanted to confirm, if I am not missing anything....

    Thanx again.

    - Bhushan

  4. #4
    Join Date
    Dec 2002
    Posts
    63
    The NIC can be a big bottleneck. WHat protocol does it use to send the data across the network? UDP, TCP, is it using a SCSI miniport driver (Encapsulating scsi calls into a udp or tcp packet) Many times, if this driver or protocol is not working, it will cause an increase in processor utilization, or the disk queue will be high. No matter what compaq tells you, if your queue is high, something is stopping the traffic from getting to the disk. Good Luck with it. I know these types of problems can sometimes be a real pain to find.

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