Yrurtj

I'm trying to understand what could have gone wrong.

for context:

I have a mirrored set with 3 drives and non-ECC memory. Not sure what else to share.

I was under assumption that having a 3-way mirror would keep me relatively secure from incidental corruptions, like failing drives, or that memory corruption would be recoverable (from one of 2 remaining disks).

But I'm probably misunderstanding.

Can anyone explain what could have gone wrong so I can secure myself for the future? I'm not too experienced with zfs.

Thanks!

$ sudo zpool status -v

  pool: dozer

 state: ONLINE

status: One or more devices has experienced an error resulting in data

    corruption.  Applications may be affected.

action: Restore the file in question if possible.  Otherwise restore the

    entire pool from backup.

   see: http://zfsonlinux.org/msg/ZFS-8000-8A

  scan: scrub repaired 0 in 8h36m with 1 errors on Sun Jan  6 02:12:32 2019

config:



    NAME                                          STATE     READ WRITE CKSUM

    dozer                                         ONLINE       0     0     1

      mirror-0                                    ONLINE       0     0     2

        ata-WDC_WD40EFRX-68N32N0_WD-WCC7K1ZKZLYK  ONLINE       0     0     2

        ata-WDC_WD40EFRX-68N32N0_WD-WCC7K6VCAZXL  ONLINE       0     0     2

        ata-ST4000DM000-1F2168_S301LW48           ONLINE       0     0     2



errors: Permanent errors have been detected in the following files:



        /dozer/path/to/my/file

You do understand that if any single non-RAIDed drive has a failure, you lose data and the same is true if one of the non-ECC memory chips has a failure: you lose data.

And even if you have:

• dual processors


• dual NICs


• dual hard drives


• ECC memory


• High-availability fail-over servers in a different data centre on a different continent

...any kind of uncorrectable error (Bug, human, Electro-Magnetic Pulse, .. ) can still lead to data loss.

And that's why, with all this nifty technology, we still have multiple off-line backups today.

_{Note: On-line backups / Data replication to a secondary Data Centre can be corrupted too in this way}