6 Replies Latest reply on May 31, 2013 2:57 PM by Nicolas Wipfli -Oracle

    Storage 6000 slow I/O, cache options


      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
          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
            I have another problem about this thread
            • 3. Re: Storage 6000 slow I/O, cache options

              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
                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
                  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:


                  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
                    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.