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<div>And hashes are not just for security. Ms Aurora worked on both ZFS and btrfs. Those filesystems use the hashes for ECC. If the hash for a block is wrong, they get the dupe block (in RAID-1, etc) with a good hash and fix it. Object FS like S3, swift, ceph use hashes also.</div>
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<div>Collisions are particularly bad for ECC.</div>
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<div>Val's kinda awesome, though I haven't seen her around much lately (she used to be a semi-regular contributor to LWN). And, yeah: in addition to finding silent corruption, it's also how block-level de-duplication happens. (Again, hopefully without collisions.) Decent, if not unbroken, hashes can still serve multiple purposes -- especially ones where performance is important.</div>
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<div>-Ken</div>
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