3 ms·
The effects are exactly as significant either way: corrupt data is written to disk. Whether the corrupt data is written one time or several times is immaterial.
by empthought 10y ago
The effects are exactly as significant either way: corrupt data is written to disk. Whether the corrupt data is written one time or several times is immaterial.
- jonathankoren 10y agoMay I introduce you to error correction? Having an error on one disk, versus multiple disks in a RAID totally matters.
- empthought 10y agoHow do you figure? If the single disk has bad data written to it, it contains bad data. If the RAID has bad data written to it, it contains bad data. Either way, the bad data is bad, because it was undetectably corrupted in memory before being written out.
- jonathankoren 10y agohttps://www.youtube.com/watch?v=osS9EaKNSI4 https://www.youtube.com/watch?v=osS9EaKNSI4 Serious question: Do they not teach Hamming codes in undergrad anymore?
- empthought 10y agoDo you not understand the problem here? The problem isn't detecting data corruption in storage, which parity checking also helps with. The problem is detecting data corruption in memory. ECC only matters after irrecoverable data loss _in memory_ has occurred. Without ECC the system will continue to operate; with ECC the system will halt without writing data at all, or correct it before storage even comes into play. Writing corrupt data once or writing it a thousand times redundantly with parity data looks exactly the same, if it's allowed to happen. It's a valid write of invalid data. Either way, the data you have on your cheap laptop drive or your six-figure storage array is corrupt. This is why the ancestor commenter is correct about the storage technology being irrelevant to the choice to use or not use ECC. I haven't been in school for many years. They taught Hamming codes, but they also taught garbage-in, garbage-out.