8 Replies Latest reply on Apr 28, 2011 5:00 PM by ECBowen

    Enterprise vs Desktop Hard Drives

    mikeklar Level 1

      Is it really worth the extra cost to go with enterprise hard drives especially when used in a RAID system?

      Having switched to desktop hard drives some years ago when the price difference was half, but now that difference (while still significant) is no longer that much, I'm wondering if it is worth going back to enterprise drives for the added rliability.

      Admitedly, I have not had any problems over the past four years with failed drives in my existing RAID arrays.

      Cheers,
      Michael

        • 1. Re: Enterprise vs Desktop Hard Drives
          Harm Millaard Level 7

          Michael,

           

          I have no definite answer for you, opinions on this seem to differ, but let me give you three examples of people with very large arrays in their system, who have no problems with consumer disks.

           

          Baz, Studio North and myself use 12+ disk arrays consisting of Samsung Spinpoints, F3 and F1's respecively and Bill Gehrke uses a similarly large array consisting of - IIRC - Seagate 7200.12's. None of us has ever had trouble with our arrays.

           

          With the number of disks involved the price difference adds up between consumer and enterprise disks and I have not seen negative effects on either of our parity raids. Beware however that the same does not apply to WD Caviar Blacks, there are numerous reports about the problems with TLER making them unsuitable for parity raids but reports say that for raid0 they are OK.

          • 2. Re: Enterprise vs Desktop Hard Drives
            mikeklar Level 1

            Thank you Harm

            I was hoping for an answer like this.  Hence I'm going to stay with my existing Seagate 2TB Barracuda XT ST32000641AS's.

            Needless to say after contacting Areca to get part number for a cable and having mentioned the HDs I will be using, their response was to consider enteprises version for reliability issues.  Not unlike the response received from Adaptec some months ago.

            Thank you again.

            Cheers,

            Michael

            • 3. Re: Enterprise vs Desktop Hard Drives
              ECBowen Most Valuable Participant

              All of the desktop drives including Seagate and Samsung besides WD do not have the time out error recovery feature the Enterprise drives have. This means if you get desktop drives regardless of manufacturer you have a chance of a drive dropping out on a parity raid just for a bad sector/sectors on the drive. A raid controller can mitigate that some but the problem is there still. The WD Tler is the same as Samsung CCTL which the Samsung drives Harm mentioned do not have either. Don't think you have avoided the issue if you get Samsung drives instead of Western Digital or Seagate. If you want to avoid it with a parity raid then you have to get the enterprise drives.

               

              http://www.samsung.com/global/business/hdd/learningresource/whitepapers/LearningResource_C CTL.html

               

              Eric

              ADK

              1 person found this helpful
              • 4. Re: Enterprise vs Desktop Hard Drives
                mikeklar Level 1

                Thank you Eric

                That web site is very informative.

                Wouild it be correct to assume that reports from the "Storage Manager" (Adpatec's Storage Manager properties report) of "Aborted commands" are indicative of this problem, i.e. lack of the error recovery feature?

                Cheers,

                Michael

                • 5. Re: Enterprise vs Desktop Hard Drives
                  ECBowen Most Valuable Participant

                  I am not familiar with Adaptec's management software anymore since I have not worked with one of their controllers in years. I would contact their tech support and ask them if that is likely the case. It likely depends on the error code for the aborted command but again that is guessing only.

                   

                  Eric

                  ADK

                  • 6. Re: Enterprise vs Desktop Hard Drives
                    RjL190365 Level 4

                    Eric,

                     

                    By a similar token, enterprise drives should not be used as single drives or in a RAID 0 configuration because the TLER/CCTL/ERC feature (which is enabled and set to a time of around 7 seconds by default) actually works against reliability in systems with no data redundancy whatsoever. The feature on the drive actually sends a command to recover the data from a redundant drive after 7 seconds or so - and if no such data exists on other drives, that data simply gets lost (which eventually leads to a corrupted drive).

                     

                    Very recent WD RE series hard drives now have TLER permanently enabled and permanently fixed at 7 seconds for both reads and writes - with absolutely no way whatsoever to change the default TLER time or even disable the feature completely. That makes such drives suitable only for use in a parity RAID array.

                     

                    For RAID 1 or RAID 10 use, it doesn't matter whether or not the drives have TLER/CCTL/ERC because entire drives or entire RAID 0 couplings get mirrored, which results in complete redundancy.

                     

                    Oh, by the way, many desktop drives allow the user to change the CCTL or ERC settings. However, such features are disabled by default although one of my desktop 1TB Samsung F3's have CCTL enabled and set to 7.5 seconds by default. That F3 came with firmware version 1AJ10002, which was short-lived (used on drives manufactured in March 2010) and quickly replaced with 1AJ10001 (which has CCTL set to Disabled by default like it should be for desktop drives).

                    • 7. Re: Enterprise vs Desktop Hard Drives
                      mikeklar Level 1

                      Thanks again Eric

                      I'm about to sell the Adaptec RAID card, right after receiving the Areca ARC-1880ix-12.  Hence, I don't feel like contacting Adaptec especially since they are very slow in responding.

                      My reason for changing cards is to increase the internal capacity as well provide expansion to external RAID enclosures.

                      Since there is a prepoderance of heavy users on this site praising Areca's cards, who am I to argue with their wisdom , but to comply

                      Cheers,

                      Michael

                      • 8. Re: Enterprise vs Desktop Hard Drives
                        ECBowen Most Valuable Participant

                        As stated in my original post, Parity raids.

                         

                        However The Time out feature should not effect a raid 1 or 0 as you state. My understanding is the controller will resend the command again to the next available block on a write instruction after the drive times out in a non parity raid on the bad block. Hence what NCQ is for besides performance increase. Also why raid controllers have their own cache or use system ram that is shadowed.

                         

                        On a read instruction the data is corrupt anyway so there is no change in the results. If the timeout limited recovery caused issues with mirrored arrays, the drive manufacturers would warn about it in the read me files or white papers and give an option to disable.

                         

                        I have seen forum posts about scripts to enable the feature on some desktop drives but it does not last after a power cycle on the current firmware  from what I have read.

                         

                        The problem in mirrored arrays has to do with the drives corrupting over time. If they do then the data loss on a rebuild due to corruption is significant. Hence why Raid 1's are good for server OS drives that require 24/7 up time but not so good for data arrays. Parity arrays minimize the data loss to corruption if you run your scheduled integrity checks weekly. Hence one of the big reasons parity raids are far more common for data storage. Raid 6 is even far less likely to corrupt with 2 levels of parity. I would not be overly confident with the raid 1 or 10's. I have seen to many mirrored arrays corrupt to be to confident in them for critical data storage especially with today's drive failure rates and symptoms. 

                         

                        Eric

                        ADK