IBM DS3400 poor write performance

Posted on 2009-04-28
Last Modified: 2013-11-14

I have a DS 3400 and DS 3300 with really poor performance in writings operations.
There is any tunnings changes to do?
I already look for the scripts and made some changes that improve the perfomance, but i´m not sure about what impact this may have to the integrity of the data.
I run the following script:
set logicaldrive mirrorEnabled=false;

Can anyone tell me about this script or share information about tunnings for this storage?
Thanks for all.
Question by:at_user
    LVL 55

    Accepted Solution

    This disables the write cache mirroring, if you've only got one controller the write cache will be disabled by default unless you issue this command since a controller failure will lead to data not being committed to the disks. It is described in the manual, can't give you page number since there aren't any,
    LVL 55

    Expert Comment

    Here's someone with the same problem -

    You can see his write cache is disabled (suspended) until he issues that command because he only has one controller.
    LVL 1

    Expert Comment

    If it all possible, I would really recommend getting the second controller and having two HBAs in your server.  Two dual port HBAs will allow you four separate fiber connections, with each HBA connected to each controller.  In addition to great performance this gives you great redundancy.  I know it really is a night and day difference because we had one controller in our DS3400 fail, and it dropped into the no-cache mode.  Performance fell into the basement, but we did keep running with no loss of data.

    I really think IBM should not even bother selling the DS3400 with one controller card.
    LVL 55

    Expert Comment

    I explained fully the meaning of this statement in the script and gave you a reference to the manual where it is explained in my comment 24258895

    Author Closing Comment

    Yes. its ok. sorry.
    But this no solve the problem.
    LVL 55

    Expert Comment

    Comment from at_user when I objected to cancelatiou:

    "Yes. its ok. sorry. But this no solve the problem."

    Proper solution to the problem is to buy another controller, then the cache will be safely mirrored.
    LVL 55

    Expert Comment

    Ricin should also get cudos for this...

    >I really think IBM should not even bother selling the DS3400 with one controller card.

    There's a good picture of a pair of similar controllers at, you can see the cache on the left is connected to the battery on the right through the board rather than by a wire, if the controller fails the contents of that cache are lost since the cache module isn't transportable and with the above setting you've already told the OS that the data has been committed to permanent media.

    Sure would like a better look at that that blue label on the DIMM though, there might be plug on it to connect to a temporary cable for safe transport.

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