Topic
  • 6 replies
  • Latest Post - ‏2012-04-27T10:06:09Z by SystemAdmin
Webio
Webio
20 Posts

Pinned topic DS3400 (two controllers) and mirrorEnabled - is it safe to disable?

‏2012-04-25T21:00:39Z |
Hello,

I'm trying to tune my DS3400 (two controllers) and I've found in few places that setting mirrorEnabled to disabled can make things work faster. Is it safe to set this param to disabled in DS3400 with two controllers?

Current LUN configuration:

Read cache: Enabled
Write cache: Enabled
Write cache without batteries: Disabled
Write cache with mirroring: Enabled
Flush write cache after (in seconds): 5.00
Dynamic cache read prefetch: Disabled

Enable background media scan: Enabled
Media scan with redundancy check: Disabled

Pre-Read redundancy check: Disabled

If someone is willing to take a look at stats then I can upload result of:

on error stop;
set performanceMonitor interval=5 iterations=360;
upload storageSubsystem file="c:\perfstats01.txt" content=performanceStats;

(script from https://www.ibm.com/developerworks/forums/thread.jspa?messageID=14470999&#14470999 from anthonyv post).

Thank you

Regards
Updated on 2012-04-27T10:06:09Z at 2012-04-27T10:06:09Z by SystemAdmin
  • Webio
    Webio
    20 Posts

    Re: DS3400 (two controllers) and mirrorEnabled - is it safe to disable?

    ‏2012-04-26T10:46:31Z  
    EDIT: I'm adding perf stats results

    Thank you.
  • SystemAdmin
    SystemAdmin
    4779 Posts

    Re: DS3400 (two controllers) and mirrorEnabled - is it safe to disable?

    ‏2012-04-26T16:16:33Z  
    • Webio
    • ‏2012-04-26T10:46:31Z
    EDIT: I'm adding perf stats results

    Thank you.
    If you'll disable cache mirroring and some volume will migrate from one controller to another (change ownership), you'll lose data left on first controller cache (write cache) not yet written to the disk. This may happen often than you think.
  • Webio
    Webio
    20 Posts

    Re: DS3400 (two controllers) and mirrorEnabled - is it safe to disable?

    ‏2012-04-26T16:32:24Z  
    If you'll disable cache mirroring and some volume will migrate from one controller to another (change ownership), you'll lose data left on first controller cache (write cache) not yet written to the disk. This may happen often than you think.
    Thank you for responding. So probably it's better to leave it enabled. On the other hand is there a way to force to have one volume attached to one controller (I have two controllers and two LUNs - so one LUN = one controller)?
  • SystemAdmin
    SystemAdmin
    4779 Posts

    Re: DS3400 (two controllers) and mirrorEnabled - is it safe to disable?

    ‏2012-04-27T07:46:43Z  
    • Webio
    • ‏2012-04-26T16:32:24Z
    Thank you for responding. So probably it's better to leave it enabled. On the other hand is there a way to force to have one volume attached to one controller (I have two controllers and two LUNs - so one LUN = one controller)?
    I am afraid it's not possible, at list hard to configure. And moreover it's dangerous, you may lose data in case some controller fail.
  • Webio
    Webio
    20 Posts

    Re: DS3400 (two controllers) and mirrorEnabled - is it safe to disable?

    ‏2012-04-27T07:52:53Z  
    I am afraid it's not possible, at list hard to configure. And moreover it's dangerous, you may lose data in case some controller fail.
    OK. Thank you. There is one more thing I'm wondering. I'm using DS3400 with XenServer (6.x) until now I was using default DMP driver but I've found that I should use RDAC instead. Is it possible that after switching to RDAC I can expect some performance improvements?
  • SystemAdmin
    SystemAdmin
    4779 Posts

    Re: DS3400 (two controllers) and mirrorEnabled - is it safe to disable?

    ‏2012-04-27T10:06:09Z  
    • Webio
    • ‏2012-04-27T07:52:53Z
    OK. Thank you. There is one more thing I'm wondering. I'm using DS3400 with XenServer (6.x) until now I was using default DMP driver but I've found that I should use RDAC instead. Is it possible that after switching to RDAC I can expect some performance improvements?
    RDAC is very close to kernel and had to be recompiled on every kernel upgrade. Newest versions of DMP have native support of LSI rdac. I don't see any "palpable" advantages of RDAC instead of DMP.