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Where is my bottleneck RRS feed

  • Question

  • I have been running my WHS for a few weeks now and can't seem to imporve the network response time from my pc to the server. I have just added a new HP dual port network card (HP NC7170 Gigabit Server Adapter) which I have setup to work in team mode (ie both ports acting as a single network port with the combined speed). I had hoped that this would sort the problem, hoping that it was the old built in network card that was the problem, but the speed still dosen't seemed to have imporved.

     

    Is there anything else that I could try to idenify where my speed bottleneck is?

     

    I should say that the server is running with a pair of SATAII, 250 GB drives.

     

    Any ideas?

     

    Mark

    Thursday, November 15, 2007 11:02 PM

All replies

  • There are a number of things that could be causing your bottleneck, there's really not enough info to make a guess.  Could be processor, RAM, drive setup (RAID, etc.), switch.

     

    Even on a full gigabit network where you have the NIC's and switch running at 1000 Mbps/Full, you won't be seeing that speed on any analyzer.  Overhead will usually reduce transfer speeds to around 40% - 50% of 'stated' network capacity, that overhead can consist of packet size, internal bus speeds, processor, RAM, hard drive connection.  Or to put it another way; EVERYTHING can affect your transfer rates.

     

    While it looks good on paper, you won't achieve 2000 Mbps connectivity on the machine with your dual port card.  You'll still be limited by whatever is sending/receiving your data.

    Friday, November 16, 2007 7:08 PM
  • Just to add to what pdbuzz said, think of it this way. SATA II supports a maximum transfer rate of 3Gb/s. That's about 384MB/s.

     

    But if you look at storagereview.com, the max transfer rate (sequential) that has been achived by a SATA drive is just a hair over 100MB/s. And that's under the best possible conditions. (An artifical benchmark that ensures that all data is read sequentially.)

     

    Most of the I/O on WHS will be a mix of sequential and random, which will cut performance subsantially. You're lucky to get 10MB/s of random I/O out of a SATA II disk. SCSI isn't much better.

     

    Add to that the fact that there is a lot of other stuff going on, and you're very unlikely to see performance gain by using both ports of your gigabit NIC.

     

    Indeed, there is a great chance that your network itself would never be able to hit 1Gb/s, much less 2Gb or more, unless you're using 10Gb switches and CAT6 cabling. And, even then, you're disks simply can't meet that demand.

     

    To achieve the tranfer rates you're looking for, you'll probably need solid state disks, or some kind of storage array (network or attached) that has 10 or more physical disks. Either way, it's probably well out of your budget. Smile

    Sunday, November 18, 2007 6:47 PM