3 Replies Latest reply on Oct 17, 2014 11:58 AM by sylvia_intel

    Is Rapid Storage Technology RAID compatible with TLER-aware disks like Western Digital Re disks (RAID edition)?

    Mark_DZ77GA-70K

      My motherboard is DZ77GA-70K. I configured software RAID that my OS provides (Windows 7). I didn't use Intel Rapid Storage Technology because I have Western Digital Re disks that support TLER (I was inspired that DZ77GA-70K provides RAID and bought Re RaidEdition disks). But to work properly that disks should be controlled by RAID controller or errors could occur. There is only one Intel System/Chassis device type item included in WD Re  compatibility list. Rapid Storage Technology is not mentioned. http://www.wdc.com/wdproducts/library/cs/2579-771897.pdf

      But OS like Windows and Linux are included in the list. Consequently, by my opinion OS-provided software RAID is preferable when using RAID specialized disks: both OS and Rapid Storage Technology are software RAID (CPU performes computations mostly) and have comparable performance but OS RAID is safer because some OS are included in above mentioned list. Maybe somebody have more information about compatibility of Rapid Storage Technology with RAID specialized disks like WD Re with regard to TLER? Is it safe to use Western Digital Re disks with Intel blue SATA ports in Rapid Storage Technology RAID mode turned on?

        • 1. Re: Is Rapid Storage Technology RAID compatible with TLER-aware disks like Western Digital Re disks (RAID edition)?
          sylvia_intel

          Hello Mark_DZ77GA-70K, I’m trying to get accurate information about your question.

           

          In the mean time, let me share this article with you http://www.wdc.com/wdproducts/library/other/2579-001098.pdf

          • 2. Re: Is Rapid Storage Technology RAID compatible with TLER-aware disks like Western Digital Re disks (RAID edition)?
            Mark_DZ77GA-70K

            Hello!

            Thank you for very comprehensive introduction. Let’s consider two scenario ( both with TLER-capable hard drives):

            Let CRITICAL_ERROR means unrecoverable error code message that leads to disk removal from RAID array. Let DEFER_HANDLING error code message means deferred error handling .

             

            1.       With TLER-capable RAID controller. Let me quote from WD article provided by you (quotation in italic):

            TLER-capable hard drives will perform the normal error recovery, and after 7 seconds, issue an error message to the RAID controller and defer the error recovery task until a later time.

            The error handling is further coordinated between the TLER-capable hard drive and the RAID card. The TLER-capable drive will respond without waiting on the error to be resolved. RAID cards are very capable of handling this with a combination of parity protection and journaling. The RAID card flags the error in the error log and proceeds to deliver data using parity protection until the drive retries its own error recovery and corrects the error”.

            So, disk encounters error, tries to handle for 7 seconds but it can’t within such period and sends error message DEFER_HANDLING, controller understands it (it can differentiate it from CRITICAL_ERROR), switches to degraded mode, recovers required data by redundant information from other disks and after some time returns from degraded mode to standard mode after considering disk has recovered from failure controller .

             

            2.       With NOT TLER-capable RAID controller:

            TLER-capable hard drives will perform the normal error recovery, and after 7 seconds, issue an error message to the RAID controller and defer the error recovery task until a later time.

            How not TLER-aware controller will understand such message and differentiate it from critical failure that must lead to disk removal from array? Most likely it can’t and it will remove disk from array and switch to degrade mode until administrator rebuilds the array. Are you agree?

            The error handling is further coordinated between the TLER-capable hard drive and the RAID card.

            How will NOT TLER-aware controller coordinate error handling further?

            • 3. Re: Is Rapid Storage Technology RAID compatible with TLER-aware disks like Western Digital Re disks (RAID edition)?
              sylvia_intel

              Mark_DZ77GA-70K, I’m still waiting to receive this information from the engineering team.

               

              In the mean time what I am going to do is to include these new questions.