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If I'm not mistaken, the tape drive automatically adds ECC to each written block, and then uses it to verify the block next time you read it. So if there's bit
by dmitrybrant 5y ago
If I'm not mistaken, the tape drive automatically adds ECC to each written block, and then uses it to verify the block next time you read it. So if there's bit rot on the tape (i.e. too much for ECC to fix), it will just be reported as a bad block with no data, and there wouldn't be any point of adding "second-order" ECC from the user end.
- BenjiWiebe 5y agoThere might be a point if you interleaved data and/or had a much higher amount of EC, such that you could recover from isolated bad blocks.
- metabagel 5y agoYou’re exactly right. There is substantial ECC in the LTO format. If the drive can recover the data, then it’s valid.
- kortex 5y agoI'm not using tapes through, I'm using ssds, flash drives, and hdds. I'm sure they have some internal ecc, but is it enough?
- dmitrybrant 5y agoCorrect, all modern storage media perform plenty of internal ECC. That's basically what "bad sectors" means: the drive wasn't able to correct the data on that sector using ECC. The drive will never return the actual "raw" data -- it's either valid data or a bad sector. This means that if you want to add your own application-level ECC, it would need to be enough to correct an entire sector's worth of missing data. For most applications this would be a prohibitive amount of extra overhead.