If a RAID5 system experiences a URE during rebuild, is all the data lost?

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I understand the argument regarding larger drives' increased likelihood of experiencing a URE during a rebuild, however I'm not sure what the actual implications are for this. This answer says that the entire rebuild fails, but does this mean that all the data is inaccessible? Why would that be? Surely a single URE from a single sector on the drive would only impact the data related to a few files, at most. Wouldn't the array still be rebuilt, just with some minor corruption to a few files?



(I'm specifically interested in ZFS's implementation of RAID5 here, but the logic seems the same for any RAID5 implementation.)










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    favorite












    I understand the argument regarding larger drives' increased likelihood of experiencing a URE during a rebuild, however I'm not sure what the actual implications are for this. This answer says that the entire rebuild fails, but does this mean that all the data is inaccessible? Why would that be? Surely a single URE from a single sector on the drive would only impact the data related to a few files, at most. Wouldn't the array still be rebuilt, just with some minor corruption to a few files?



    (I'm specifically interested in ZFS's implementation of RAID5 here, but the logic seems the same for any RAID5 implementation.)










    share|improve this question























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      I understand the argument regarding larger drives' increased likelihood of experiencing a URE during a rebuild, however I'm not sure what the actual implications are for this. This answer says that the entire rebuild fails, but does this mean that all the data is inaccessible? Why would that be? Surely a single URE from a single sector on the drive would only impact the data related to a few files, at most. Wouldn't the array still be rebuilt, just with some minor corruption to a few files?



      (I'm specifically interested in ZFS's implementation of RAID5 here, but the logic seems the same for any RAID5 implementation.)










      share|improve this question













      I understand the argument regarding larger drives' increased likelihood of experiencing a URE during a rebuild, however I'm not sure what the actual implications are for this. This answer says that the entire rebuild fails, but does this mean that all the data is inaccessible? Why would that be? Surely a single URE from a single sector on the drive would only impact the data related to a few files, at most. Wouldn't the array still be rebuilt, just with some minor corruption to a few files?



      (I'm specifically interested in ZFS's implementation of RAID5 here, but the logic seems the same for any RAID5 implementation.)







      raid zfs zfsonlinux






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      process91

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          I would explain it the other way around;



          If the RAID controller don’t stop on URE, what could happen ?



          I lived it on a server, the RAID never noticed the URE and after the rebuild a corruption started to build up on the entire RAID volume.



          The disk started to get more bad sector after the rebuild and the data started to be corrupt.



          The disk was never kicked off the RAID volume, the controller fail is job to protect the data integrity.



          That example is wrote to make you think that a controller can’t thrust a volume with URE at all, its for the data integrity, as the volume is not meant to be a backup but a resiliance to a disk failure






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            I see the new moderators are all constantly checking the site, looking for things to do...
            – Ward♦
            44 mins ago










          • @Ward haha, yeah :)
            – yagmoth555♦
            40 mins ago

















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          I'd suggest reading this question and answers for a bit more background. Then go and re-read the question you linked to again.



          When someone says about this situation that "the RAID failed," it means you lost the benefit of the RAID - you lost the continuous access to data that was the reason you set up the RAID array in the first place.



          You haven't lost all the data, but the most common way to recover from one dead drive plus (some) UREs on (some of) the remaining drives would be to completely rebuild the array from scratch, which will mean restoring all your data from backup.






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            2 Answers
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            2 Answers
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            up vote
            1
            down vote













            I would explain it the other way around;



            If the RAID controller don’t stop on URE, what could happen ?



            I lived it on a server, the RAID never noticed the URE and after the rebuild a corruption started to build up on the entire RAID volume.



            The disk started to get more bad sector after the rebuild and the data started to be corrupt.



            The disk was never kicked off the RAID volume, the controller fail is job to protect the data integrity.



            That example is wrote to make you think that a controller can’t thrust a volume with URE at all, its for the data integrity, as the volume is not meant to be a backup but a resiliance to a disk failure






            share|improve this answer
















            • 1




              I see the new moderators are all constantly checking the site, looking for things to do...
              – Ward♦
              44 mins ago










            • @Ward haha, yeah :)
              – yagmoth555♦
              40 mins ago














            up vote
            1
            down vote













            I would explain it the other way around;



            If the RAID controller don’t stop on URE, what could happen ?



            I lived it on a server, the RAID never noticed the URE and after the rebuild a corruption started to build up on the entire RAID volume.



            The disk started to get more bad sector after the rebuild and the data started to be corrupt.



            The disk was never kicked off the RAID volume, the controller fail is job to protect the data integrity.



            That example is wrote to make you think that a controller can’t thrust a volume with URE at all, its for the data integrity, as the volume is not meant to be a backup but a resiliance to a disk failure






            share|improve this answer
















            • 1




              I see the new moderators are all constantly checking the site, looking for things to do...
              – Ward♦
              44 mins ago










            • @Ward haha, yeah :)
              – yagmoth555♦
              40 mins ago












            up vote
            1
            down vote










            up vote
            1
            down vote









            I would explain it the other way around;



            If the RAID controller don’t stop on URE, what could happen ?



            I lived it on a server, the RAID never noticed the URE and after the rebuild a corruption started to build up on the entire RAID volume.



            The disk started to get more bad sector after the rebuild and the data started to be corrupt.



            The disk was never kicked off the RAID volume, the controller fail is job to protect the data integrity.



            That example is wrote to make you think that a controller can’t thrust a volume with URE at all, its for the data integrity, as the volume is not meant to be a backup but a resiliance to a disk failure






            share|improve this answer












            I would explain it the other way around;



            If the RAID controller don’t stop on URE, what could happen ?



            I lived it on a server, the RAID never noticed the URE and after the rebuild a corruption started to build up on the entire RAID volume.



            The disk started to get more bad sector after the rebuild and the data started to be corrupt.



            The disk was never kicked off the RAID volume, the controller fail is job to protect the data integrity.



            That example is wrote to make you think that a controller can’t thrust a volume with URE at all, its for the data integrity, as the volume is not meant to be a backup but a resiliance to a disk failure







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 54 mins ago









            yagmoth555♦

            10.8k31441




            10.8k31441







            • 1




              I see the new moderators are all constantly checking the site, looking for things to do...
              – Ward♦
              44 mins ago










            • @Ward haha, yeah :)
              – yagmoth555♦
              40 mins ago












            • 1




              I see the new moderators are all constantly checking the site, looking for things to do...
              – Ward♦
              44 mins ago










            • @Ward haha, yeah :)
              – yagmoth555♦
              40 mins ago







            1




            1




            I see the new moderators are all constantly checking the site, looking for things to do...
            – Ward♦
            44 mins ago




            I see the new moderators are all constantly checking the site, looking for things to do...
            – Ward♦
            44 mins ago












            @Ward haha, yeah :)
            – yagmoth555♦
            40 mins ago




            @Ward haha, yeah :)
            – yagmoth555♦
            40 mins ago












            up vote
            1
            down vote













            I'd suggest reading this question and answers for a bit more background. Then go and re-read the question you linked to again.



            When someone says about this situation that "the RAID failed," it means you lost the benefit of the RAID - you lost the continuous access to data that was the reason you set up the RAID array in the first place.



            You haven't lost all the data, but the most common way to recover from one dead drive plus (some) UREs on (some of) the remaining drives would be to completely rebuild the array from scratch, which will mean restoring all your data from backup.






            share|improve this answer
























              up vote
              1
              down vote













              I'd suggest reading this question and answers for a bit more background. Then go and re-read the question you linked to again.



              When someone says about this situation that "the RAID failed," it means you lost the benefit of the RAID - you lost the continuous access to data that was the reason you set up the RAID array in the first place.



              You haven't lost all the data, but the most common way to recover from one dead drive plus (some) UREs on (some of) the remaining drives would be to completely rebuild the array from scratch, which will mean restoring all your data from backup.






              share|improve this answer






















                up vote
                1
                down vote










                up vote
                1
                down vote









                I'd suggest reading this question and answers for a bit more background. Then go and re-read the question you linked to again.



                When someone says about this situation that "the RAID failed," it means you lost the benefit of the RAID - you lost the continuous access to data that was the reason you set up the RAID array in the first place.



                You haven't lost all the data, but the most common way to recover from one dead drive plus (some) UREs on (some of) the remaining drives would be to completely rebuild the array from scratch, which will mean restoring all your data from backup.






                share|improve this answer












                I'd suggest reading this question and answers for a bit more background. Then go and re-read the question you linked to again.



                When someone says about this situation that "the RAID failed," it means you lost the benefit of the RAID - you lost the continuous access to data that was the reason you set up the RAID array in the first place.



                You haven't lost all the data, but the most common way to recover from one dead drive plus (some) UREs on (some of) the remaining drives would be to completely rebuild the array from scratch, which will mean restoring all your data from backup.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 45 mins ago









                Ward♦

                11.4k53855




                11.4k53855



























                     

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