I've done some reading and it seems like the only real difference is the level of error checking that happens, but if I've got a pair in RAID 1 that should counteract this to some extent. Currently I'm looking to put them into my QNAP TS-230, but I'm considering building my self a little home server where I'd use all three in RAID5.
Whilst it true about them being optimised for video streaming, the error correction behaviour can be considerably different to either desktop drives or specific NAS drives.
- Desktop drives upon encountering an error will continue to retry reading the data, in the hope that they can recover the data (during this time the drive is basically unavailable and is what causes desktop drives to drop out of RAID arrays)
- NAS drives upon encountering an error, normally don't try and recover the data - they immediately report the error back to the raid controller (either hardware or software), and that makes a decision what to do (e.g. recover from another copy in RAID1, or reconstruct using Parity in RAID5/6)
- Surveillance and drives used in e.g. TV Set top boxes often just ignore the error - particularly when writing (as what does it matter if a frame of a CCTV or TV recording is missing - you just get a tiny glitch in playback), in theory meaning that a RAID controller may not get the expected results to be able to make a "safe" decision.
I personally wouldn't consider using them for important data.
Probably more importantly: a reminder that raid 1 with 2 drives will only flag an error, it cannot attempt automatically correct the value. You need 3 drives or more in the array to be able to spot a single drive error and for the drives to "vote" on what's correct. The only edge case on that I guess is if one of the 2 totally dies then there's a majority of one anyway in the vote...
That's not exactly correct - Drives don't vote - it's up to the RAID controller (either hardware or software) to make that decision
Thanks I was not aware of that, but it makes a lot of sense having a validation drive. So I guess I'd be foolish to use these in RAID 1, but set them up as RAID 5 might be a possibility.
RAID5 isn't a great choice for important storage (although with any type of storage make sure you have a separate backup), as RAID5 rebuilds for larger disks take a long time (and during which they put more strain on the remaining disks, which increases the chance of another failure)
If you are looking at building a home server anyway - then Unraid is often a much better option. It offers the reliability of a RAID5 (i.e. parity protection of data), but data isn't striped, and is stored conventionally on disk, so even if several disks fail - you can still read the remaining disks.
