4 ms·
In RAID6 you can find which of the different combinations shows a mismatch and which combination doesn't. Run through all combinations and find the one that sho
by baruch 11y ago
In RAID6 you can find which of the different combinations shows a mismatch and which combination doesn't. Run through all combinations and find the one that shows no mismatch, the dropped drive is the one with the bad data, rewrite it and go on with your life.
This can only detect one bad drive, if you have two you are toasted.
- Ded7xSEoPKYNsDd 11y agoFWIW Linux software RAID doesn't do that. I think the argument was that differences like this were mostly related to power loss where some disks have the new data and others the old data. And at the block layer, it's impossible to tell which is which and so the code just picks a winner basically at random. I'm not 100% convinced myself that a 'majority wins' strategy like you described wouldn't be superior, but I can see why they decided otherwise.
- SirMaster 11y agoExcept Synology uses MDRAID (Linux Kernel RAID) and even in RAWID 6 mode it doesn't do this. It just overwrites the corrupt sector with a new value to make the parity data consistent. It doesn't know which is right or wrong even though technically with RAID6 it would be possible to determine.