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Opinions about RAID 1 and protection against Data Corruption
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Opinions about RAID 1 and protection against Data Corruption

Hi,

I wanted an opinion from you guys about this article about RAID: https://blog.storagecraft.com/truth-raid-data-corruption/

Mainly about the paragraph:

The goal of RAID, particularly level 1, is creating two equal disks so if one fails physically, your data is still available on the other. Unfortunately, RAID is incapable of determining which of the two disks is bad. Therefore, if no failure is detected, the system assumes everything is accurate and data from the corrupted drive is automatically copied to the second drive.

Is this correct? Is it true that there is no system alarm when one of the drives suffers from bit rot? I still see many hosts offering RAID 1.

So the question is: Is RAID 1 worth having? Has it saved you (a sysadmin/hosting provider) from potential problems?

Thanks.

Comments

  • deankdeank Member, Troll
    edited September 2018

    I prefer JBOD in personal servers.

    Raid 1 or 5 or 10 in production simply because you need to have a combined storage with some protection.

    When it rains, it pours. When raid fails, you are going to cry along with your clients.

    Thanked by 1simpleguy8288
  • @simpleguy8288 said:
    So the question is: Is RAID 1 worth having? Has it saved you (a sysadmin/hosting provider) from potential problems?

    Repeat after me:
    "Raid is not a backup, Raid is to maintain uptime"

    Thanked by 2dfmcvn simpleguy8288
  • WebProjectWebProject Host Rep, Veteran

    @Actavus said:

    @simpleguy8288 said:
    So the question is: Is RAID 1 worth having? Has it saved you (a sysadmin/hosting provider) from potential problems?

    Repeat after me:
    "Raid is not a backup, Raid is to maintain uptime"

    >

    The other one repeat after me: Backup, backup and again backup :smile:

  • deankdeank Member, Troll
    edited September 2018

    And don't repeat after me: Backup is for pussies. Real men thrive on danger. You live only once. Risk it.

    Thanked by 2Actavus dfmcvn
  • What's a backup?!

  • I use BTRFS RAID1 so I can have both increased availability (mirroring) as well as data corruption detection (weekly scrubs).

    Thanked by 1simpleguy8288
  • deankdeank Member, Troll

    Backup: Back + up ↺

    A slang used to refer arse intercourse.

    Thanked by 1Yura
  • @WebProject said:

    @Actavus said:

    @simpleguy8288 said:
    So the question is: Is RAID 1 worth having? Has it saved you (a sysadmin/hosting provider) from potential problems?

    Repeat after me:
    "Raid is not a backup, Raid is to maintain uptime"

    >

    The other one repeat after me: Backup, backup and again backup :smile:

    And the last after me : test your backup, test your backup of backup

    Thanked by 1WebProject
  • jsgjsg Member, Resident Benchmarker

    @simpleguy8288 said:

    ... Unfortunately, RAID [1] is incapable of determining which of the two disks is bad. Therefore, if no failure is detected, the system assumes everything is accurate and data from the corrupted drive is automatically copied to the second drive.

    Is this correct?

    Yes that is correct and has been demonstrated in tests.

    Note however that there are Raid 1 implementations which go beyond merely mirroring. ZFS with its checksums is an example.

    Thanked by 1simpleguy8288
  • simpleguy8288 said: Unfortunately, RAID is incapable of determining which of the two disks is bad.

    Partially, any RAID worth its salt can detect and repair errors that were caused by hardware problems (e.g. bad sectors). Many hardware RAID controllers will scrub to detect these types of errors automatically.

    Bit Rot is a completely different problem, and be definition, is not a hardware error. Some RAID 1 implementations, e.g. BTRFS, Ceph, Storage Spaces, etc. can detect and repair Bit Rot automatically. Traditional RAID was never designed with that feature.

    Also remember, RAID 1 is not just for data redundancy, but it also improves read performance.

    Thanked by 1simpleguy8288
  • mfsmfs Banned, Member

    If you're that concerned use an appropriate filesystem, e.g. RAIDZ1, or a btrfs raid if you're a #yolo fellow; RAID alone isn't a protection against bit rot pretty much as it isn't a backup. Whether or not is it worthy to be concerned by bit rot with nowadays' disks is open to discussion and it has been challenged already by some. Chances are that you're wrapping your head for something well beyond your threat model

    Thanked by 1simpleguy8288
  • @Actavus said:

    @simpleguy8288 said:
    So the question is: Is RAID 1 worth having? Has it saved you (a sysadmin/hosting provider) from potential problems?

    Repeat after me:
    "Raid is not a backup, Raid is to maintain uptime"

    Real men no need backup 😎🆒

    Thanked by 1WebProject
  • Thank you, everybody, for your views and advice. Much appreciated!

  • You should be getting larm at os level if 1 disk fails else raid of no use. IT IS better not to have raid but instead a separate backup storage to save data. use disk as it is. btw better go for raid10 but you will end up buying many disks.

    Thanked by 1simpleguy8288
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