Depending on how it's configured, it is possible to have a double drive failure occur without data loss or loss of availability. For example, if only certain drives fail (such as one from each mirror) then there will be no loss of data or availability. On the other hand, if both drives in a mirror set were lost, then the RAID-10 volume would be compromised.
If your concern is a double drive failure yet you need the performance of a RAID-10, then look at doing a six drive scenario, in which there are three drives per mirror. Or, look at a hybrid model such as a vertical and horizontal stripe across controllers again using multiple drives.
- Read more on RAID 10 minimum drives in this expert tip
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