This discussion is archived
6 Replies Latest reply: May 31, 2013 7:57 AM by Nicolas Wipfli - Oracle RSS

Storage 6000 slow I/O, cache options

tien86 Newbie
Currently Being Moderated
Hi,

My storage 6540 is running slow. Volumes I map to server have write speed average at 5MB/s.

I want to tray this issue from cache policy. This is cache options I find from collection data about a volume.
Read cache active: true
Write cache enabled: true
Write cache active: false
Write cache without batteries: false
Write cache with mirroring enabled: true
Write cache with mirroring active: false

Is it affect to my I/O ? Can I change this option? Where to find documents about cache policy of storage 6000 family.

Thank and Regards.
  • 1. Re: Storage 6000 slow I/O, cache options
    tien86 Newbie
    Currently Being Moderated
    Hi i found this today, so i will have to replace a new Battery before furthur tracking.

    Battery Faults.

    A battery fault can cause write cache to become disabled. Write cache will not be re-enabled until the battery has been replaced and fully charged. A newly replaced battery can take upwards of 12 hours to recharge. 

    Pasted from <https://support.oracle.com/epmos/faces/ui/km/SearchDocDisplay.jspx?_afrLoop=1483553035068416&type=DOCUMENT&id=1411763.1&displayIndex=2&_afrWindowMode=0&_adf.ctrl-state=106iryozc1_173>

    Thanks and Regards.
  • 2. Re: Storage 6000 slow I/O, cache options
    tien86 Newbie
    Currently Being Moderated
    I have another problem about this thread
  • 3. Re: Storage 6000 slow I/O, cache options
    tien86 Newbie
    Currently Being Moderated
    Hi.

    We cannot obtain a battery at this moment. Is there any way to enable write cache without battery to true?
  • 4. Re: Storage 6000 slow I/O, cache options
    McW (Oracle) Explorer
    Currently Being Moderated
    Battery is there to ensure write cache can be maintained during a power failure. Enabling write cache without battery (btw, not a user option) is a dangerous proposition bec. once an I/O request is written to cache by the controller, it is considered complete and the host application will be informed with an i/o success. The lost of write cache before the content is written to disk, means data lost that is completely undetectable by the host application unless the host file system structure provide alternative error detection mechanism (such as a block level checksum). This data corruption can potentially go undetected forever since as far as the host is concerned it was successfully written, while on the storage side, the RAID structure (if any) is intact and there would be no parity check error since write cache was "lost" and not bec. it was partially written.

    It's a good idea to keep write cache disabled while waiting for a new battery.
  • 5. Re: Storage 6000 slow I/O, cache options
    800381 Explorer
    Currently Being Moderated
    It can be done. If you have SANtricity, it's an option you can easily select.

    With CAM, you have to use the CLI. See:

    http://docs.oracle.com/cd/E19259-01/820-6662-10/820-6662-10.pdf

    Page 177 or thereabouts is apropos.

    But as pointed out, doing so is playing with serious fire. You shouldn't even think about doing it unless your array is on a UPS that you trust entirely.
  • 6. Re: Storage 6000 slow I/O, cache options
    Nicolas Wipfli - Oracle Expert
    Currently Being Moderated
    With CAM you can also use the Browser User Interface (BUI) to enable "Write Cache Without Battery" for each individual volume. The CAM CLI is not the only option.

    Nicolas

Legend

  • Correct Answers - 10 points
  • Helpful Answers - 5 points