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Thread: XServe RAID and catalyst

  1. #1

    XServe RAID and catalyst

    Hugh and myself made some rather surprising discoveries this week, about the performance of a networked XServe RAID connecting multiple Macs using a fibre channel switch:


    we configured one channel ( one half of xserve raid ) - to drive 3 catalysts.
    the one half was set up as 3 separate 2 drive raids.

    3 catalyst systems running on dual g5's were then connected to the xserve raid via the Qlogic 5200 fibre switch - everything was connected to a fibre channel switch.

    each raid volume called 'Raid 1', 'Raid 2', 'Raid 3' mounted on all the macs! through the switch - without any configuration!
    meaning volumes are totally shareable - WITHOUT any extra configuration of anything.
    XSAN was not required.

    We started off by playing back 4 layers on each catalyst - all worked fine.


    i think we might be able to drive up to 6 ( or even 8 ) catalyst media servers - each with 4- 6 layers from a single xserve raid.

    Ultimate performance will depend on the data saturation characteristics of the fibre channel switch, and the end user content requirements.

    we have not finished testing yet.
    im still not yet sure whether this will work so well with long clips, which cannot be completely loaded in the cache.

    the key to this is to divide the xserve raid up into smaller drive sets- 2 or 3 drives /raid set.
    as reagan initially reported the performance at standard definition is not better with 7 drives than with 2 - a 7 drive raid set can playback 7-8 layers - but so can a 2 volume raid set.

    this is because playing back 6-7-8 layers the bottleneck problem becomes a processor limitation.

    So dividing up 14 drives in the biggest xserve raid will give you 3 raid sets/channel, each with 2 or 3 drives.

    Each Catalyst mac media server runs from its own RAID set - so the data access for each server does not collide across raid volumes.
    But all volumes are readable on all macs networked through the fibre channel card.

    The fibre channel system means that you have actually directly networked all your volumes together.

    This has an enormous potential to help in the content management of large shows, as any mac connected to the fibre channel switch can see all RAID volumes.

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  4. #4
    I drew a diagram of the proposed network layout.

    Each mac should ideally access files only on its own RAID set- to maximise performance, but all volumes will mount on desktops of all macs.


    We dont have multiple XServe RAIDS to test but we believe that multiple units can also be plugged directly into the fibre channel switch, and shared between computers.
    Attached Files Attached Files

  5. #5

    XServe RAID Economics

    Is the XServe RAID expensive?

    If you consider that each single XServe RAID - configured as 6 RAID sets, you get 4 volumes with 800GB and 2 volumes with 1200GB.
    You are getting a LOT of storage capacity in one unit.5.6TB

    The retail price of the largest XServeRAID is $13000.
    Using this to drive 6 Catalysts is then ~$2000/server.
    Add 8 port Fibre switch. $2000
    Fibre channel cards are about the same cost as scsi cards

    A SCSI disc array with 800GB capacity using 140GB drives at $600/drive is 5*600= $3000

    The XServe RAID is 50% cheaper per RAID set for the same drive size than using SCSI.
    And you can network this between multiple macs, you cannot do this with SCSI.

  6. #6

    Which Raid Levels did you run the Xserv on?


    Jan Opseth

  7. #7
    Quote Originally Posted by Jan Opseth

    Which Raid Levels did you run the Xserv on?


    Jan Opseth
    RAID 0.

    No redundancy

  8. #8
    Another possible nice thing with this, is that you can rent Xserve RAID systems from a number of vendors....

  9. #9
    Quote Originally Posted by jasonrudolph
    Another possible nice thing with this, is that you can rent Xserve RAID systems from a number of vendors....
    if you do rent-
    Make sure you have enough time to configure the raid. it takes a day or so to change the raid setup!

    I like it because really it was almost plugnplay.
    Fibre channel cards didnt need configuring, fibre switch didnt need configuring.
    Maybe we got lucky.

  10. #10
    Quote Originally Posted by samsc
    RAID 0.

    No redundancy

    I know you folks have planty to but do you have the time/"wanto" too
    test raid 5? to see any performance drops/or rices?

    Can u change stripe sizes on an Xserv Raid?


    Jan O
    Last edited by Jan Opseth; 18-03-2005 at 01:20 AM.

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