In Snapshot RAID, what happens if I lose a drive while my RAID is unsynchronized?

If your Snapshot RAID is unsynchronized because you’ve only added new files, then recovery will be based of the following two scenarios:

  • If the failed drive did not contain new data, you are fine. The failed drive will be fully recovered. Note that renamed and moved files are a non-issue during recovering, and FlexRAID will recover despite them and without issues.
  • If the failed drive did contain new data that is unsynchronized, you will lose that new unsynchronized data but all other data will be fully recovered.

However, if you edited or deleted data then you run a higher risk of losing some data on the failed drive, but only up to the unsynchronized portion. The remainder of the data will be recoverable. So, if you edited or deleted only 1GB of data, only 1GB would not be recoverable. Note that when running multiple parity levels, 100% recovery is possible even if the RAID is unsynchronized.

When using Snapshot RAID, you should always ensure to re-synchronize the RAID after data changes have occurred.
If you re-synchronize the RAID often, the probability of a drive failing while the RAID is unsynchronized will be extremely low.

Again, this is only a limitation of the Snapshot RAID feature of FlexRAID as the Real-Time RAID feature has no such limitation.

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2 Responses to “In Snapshot RAID, what happens if I lose a drive while my RAID is unsynchronized?”

  1. Jeff June 19, 2011 at 9:27 PM #

    What do you mean “If the failed drive did contain new data”, I am pretty sure I know what you mean (the data is being stripped across X number of drives) but anything added to that array before it has been synchronized will not be recovered if there is a drive failure. But the data is never on just one disk… right?

  2. Brahim June 25, 2011 at 8:26 AM #

    FlexRAID does not stripe data. In Snapshot mode, new data that was added onto the drive that failed and has not been synchronized will not be recoverable.

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