I'm adding a bunch of 10TB drives to my system next week, I've got 6 of them.
I'm currently torn between making a striped mirror (3x vDevs of 2 drives) or a 5 disk RAIDZ2 with a hot-spare. They equate to approx the same amount of usable storage.
The striped mirror here is only gaurenteed to tolerate the loss of 1 drive. (In theory it could tolerate the loss of 3 but only if they were the 'right' drives).
So the RAIDZ2 setup is twice as reliable as it could tolerate the loss of 2 drives, plus I'll have a spare?
On the surface the RAIDZ2 is a clear winner. However I've always had a weird affinity to mirrors because (probably just in my head) the data is always in one place, rather than being spread accross many drives, so from a disaster recovery stand-point this seems... safer. Plus I read this article https://jrs-s.net/2015/02/06/zfs-you-should-use-mirror-vdevs-not-raidz/ which suggests RAIDZ is the worst possible choice. It seems to suggest that rebuilding a RAIDZ2 member is far more risky in terms of further drive failure than accepting the slightly reduced drive failure tolerance of the mirrored setup.
So then I went down the rabbit hole of reading up about the rebuild times of large (i.e. 10TB) drives and that seems to be a world of rumor and conjecture without a great deal of empirical evidence, some people assume a rebuild rate of 10MB/sec others 150MB/sec - so it's very hard to be able to draw a conclusion!
Help?!
I'm currently torn between making a striped mirror (3x vDevs of 2 drives) or a 5 disk RAIDZ2 with a hot-spare. They equate to approx the same amount of usable storage.
The striped mirror here is only gaurenteed to tolerate the loss of 1 drive. (In theory it could tolerate the loss of 3 but only if they were the 'right' drives).
So the RAIDZ2 setup is twice as reliable as it could tolerate the loss of 2 drives, plus I'll have a spare?
On the surface the RAIDZ2 is a clear winner. However I've always had a weird affinity to mirrors because (probably just in my head) the data is always in one place, rather than being spread accross many drives, so from a disaster recovery stand-point this seems... safer. Plus I read this article https://jrs-s.net/2015/02/06/zfs-you-should-use-mirror-vdevs-not-raidz/ which suggests RAIDZ is the worst possible choice. It seems to suggest that rebuilding a RAIDZ2 member is far more risky in terms of further drive failure than accepting the slightly reduced drive failure tolerance of the mirrored setup.
So then I went down the rabbit hole of reading up about the rebuild times of large (i.e. 10TB) drives and that seems to be a world of rumor and conjecture without a great deal of empirical evidence, some people assume a rebuild rate of 10MB/sec others 150MB/sec - so it's very hard to be able to draw a conclusion!
Help?!