4 bay NAS

[Bego2K]

I'm looking at a 4 bay NAS and up until about an hour ago was going to go with raid 5 with 4 3tb WD Red drives. That was until I read that raid 5 is very unreliable on large drives.
I am wondering what the best options are, When I read about failures with raid 5 they were talking about large arrays like 36TB where as I'm only looking at a 12TB array obviously with parity I lose 1 drive so I get 9TB usable storage. What is the likeliness of a second drive failing on a rebuild? then there's the URE issue..
Am I just better going raid 10? but then what's the likeliness of a drive failing from the usable and mirror at the same time?

Advice much appreciated.

 

[Habakkuk]

The odds are low - you're more likely to mess up recovery & damage the data during rebuild.

However RAID is not a back-up - please ensure you have a off-line copy of any sensitive data.

 

[Armageus]

Ultimately depends what you are planning on storing?

If it becomes a minor inconvenience to rebuild e.g. ripped blurays for a HTPC etc, then RAID5 is still a valid option. If it's for irreplaceable content such as family photos then I would go for RAID10.

The odds of 2 drives failing in raid10 is no more likely than having 2 drives fail in raid 5 (and if 2 drives fail in RAID5 you are still looking at data loss) - and providing they aren't in the same mirror you won't lose data anyway. The main benefit of RAID10 over RAID5, is that the rebuild is much quicker (reducing the window for another failure) and only involves 1 drive (rather than stressing all remaining drives)

If your data is important though, as has already been said RAID is not a Backup (in that while it protects against drive failure, it does not protect against corruption, viruses, accidental deletion). 12TB is a lot to backup, but if you haven't already you need to look at USB or similar enclosures, and ideally a cloud backup option.

 

[Bego2K]

Thanks guys looking into cloud backup solution.

 

[DarkMatter]

I use one drive for family photos etc then a flexraid box (on windows 10) for a 4 disc array. Seems to work well.