Comment by Polizeiposaune
4 days ago
In some circumstances it can.
Every ZFS block pointer has room for 3 disk addresses; by default, the extras are used only for redundant metadata, but they can also be used for user data.
When you turn on ditto blocks for data (zfs set copies=2 rpool/foo), zfs can fix corruption even on single-drive systems at the cost of using double or triple the space. Note that (like compression), this only affects blocks written after the setting is in place, but (if you can pause writes to the filesystem) you can use zfs send|zfs recv to rewrite all blocks to ensure all blocks are redundant.
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