3 ms·
True, and I’ve considered doing that, but it means you’re doing 2/1 or at best 3/2 storage storage rates. Raid only uses XOR, but Reed-Solomon or other FEC code
by elcritch 7y ago
True, and I’ve considered doing that, but it means you’re doing 2/1 or at best 3/2 storage storage rates. Raid only uses XOR, but Reed-Solomon or other FEC codes can produce way better error correction rates. Say full recovery for standard storage error rates using only 1/10 the extra space along with more computation at recovery time. Add CPU hardware support like AES and then even battery devices could use it.
- elcritch 7y agoArticle on fec’s and storage, seems Ceph utilizes FEC: https://www.networkcomputing.com/data-centers/putting-erasure-codes-work https://www.networkcomputing.com/data-centers/putting-erasur...
- zozbot234 7y agoThe device mapper framework is open source. You could just extend it with additional ECC modes if those would be useful to you, and then these would become usable in both RAID and unRAID setups.
- p_l 7y agoRAID uses more than XOR once you get past RAID5, usually. The lesser known bit about ZFS RAIDZ for example is that each level introduces new error correction code. RAIDZ1 uses plain XOR. RAIDZ1 has one disk with XOR one disk with Reed-Solomon. RAIDZ3 adds third disk which has Reed-Solomon but implemented differently. The effect is that you have 3 different codes available.