As not a NAS specialist. It’s hard to find on the rockstor website weather Rockstor has a self correcting feature from FreeNAS. In FreeNAS if one drive is mirrored on another and on file on one for the drives is corrupted then FreeNAS automatically makes a new copy from the good file on on drive with the corrupted file This is done automatically every time the file is read or written. This feature is turned on by default in FreeNAS.
Does Rockstor have this feature and is it turned on by default when installed on two drives mirrored?
Yes - BTRFS, the filesystem that Rockstor is built on, has the same behaviour as ZFS, the filesystem that FreeNAS is built-on, in this respect. If a block is read and detected as faulty i.e. a checksum for the data read doesn’t match the checksum recorded in the directory when the block was written, and there is another version of the block available i.e. using a parity block or a mirror, this correct version of block will beread and the data rewritten to a different location on disc, ‘healing’ the disc. Recommended for both systems is to have a background task to read every block in the system, healing any problems found. This task is known as ‘scrubbing’, and allows you to detect any problems early e.g. may be a disc/controller is failing, and needs attention.