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Thread: iSCSI performance unacceptable

  1. #11

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    Make sure the LUN has the Write Back enabled. Also check the test.log and tell me what the hdparm are for the reads - cut an past on your post.

    Also SeanLeyne is correct that those drives are slow "Seagate 5900 RPM" with the seek times at that rate dont expect great performance values especially again a RAID controller with faster drives again slow drives with no RAID controller to tune with the Write Cache that is available with the RAID controller.
    All the best,

    Todd Maxwell


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  2. #12

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    Just for the fun I build another unit with exactly the same spec & this time used FreeNAS FreeNAS-8.0-RELEASE-amd64.Full_Install

    Default install with same tweaks as per Gr-R recommendation

    Both servers connected to the same switch via identical Cat6 cable

    So all in all the hardware is a TWIN, just the OS is different

    Then I used Copy Handler 1.32 to copy same 1.59Gb of data from internal HD to both units:

    First FreeNAS:

    45 sec, avg 36.26 MB/s

    Then DSS:

    4 min 16 sec, 6.37 MB/s

    Surely not what one should/could expect?


    And that is exactly what I see during normal use of the machine.
    Open-e ISCSI volume can not be accessed when something is writing to it

    With FreeNAS I can read (open large rar) while another process writes to the volume (ie file copy)

    sebus

  3. #13

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    Can you check the test.log and tell me what the hdparm are for the reads - cut an past on your post.
    All the best,

    Todd Maxwell


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  4. #14

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    And where is test.log?

    sebus

  5. #15

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    Status > Hardware > Log then click on the Download button and open the log file and look for the test.log

    Or learn here:

    http://www.open-e.com/library/webcasts-and-videos/

    2010.11 How to view and understand the log file from DSS V6
    All the best,

    Todd Maxwell


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  6. #16
    Join Date
    Aug 2010
    Posts
    404

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    Quote Originally Posted by Gr-R View Post
    Try this:

    1. From the console, press CTRL+ALT+W,
    2. Select Tuning options -> iSCSI daemon options -> Target options,
    3. Select the target in question,
    4. change the MaxRecvDataSegmentLength and MaxXmitDataSegmentLength values to the maximal required data size

    (check w/ the initiators to match).

    maxRecvDataSegmentLen=262144
    MaxBurstLength=16776192
    Maxxmitdatasegment=262144
    FirstBurstLength=65536
    DataDigest=None
    maxoutstandingr2t=8
    InitialR2T=No
    ImmediateData=Yes
    headerDigest=None
    Wthreads=8
    As an update, please keep in mind when using latest builds of DSS, MaxBurstLength variable cannot be set to 16776192 because such value was only supported in iSCSI Enterprise Target (IETD), additionally With reads variable also works only with (IETD).

    Max value in SCST for MaxBurstLength is 1MB, 10485760.

    In case when you use MaxBurstLength=16776192 and make the update, scripts during starting the system fix the values to default one (262144).

    So you may leave MaxBurstLength variable values as the default value or you may use the max value which is 10485760.

  7. #17

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    @Al-S

    You got a bad Typo there:

    Max value in SCST for MaxBurstLength is 1MB, 10485760
    .
    .
    So you may leave MaxBurstLength variable values as the default value or you may use the max value which is 10485760.
    should read:

    Max value in SCST for MaxBurstLength is 1MB, 1048576
    So you may leave MaxBurstLength variable values as the default value or you may use the max value which is 1048576.


    Just one "0" to much...

    Regards,
    Ralph

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