[Gluster-users] distribute replicated volume and tons of questions

[Joe Julian]

On 02/22/17 11:25, Gandalf Corvotempesta wrote:
> 2017-02-22 19:27 GMT+01:00 Joe Julian <joe at julianfamily.org>:
>> I can't answer ZFS questions. I, personally, don't feel it's worth all the
>> hype it's getting and I don't use it.
> the alternative would be XFS, but:
> 1) i'm using XFS on a backup server. I've *NEVER* seen so many crashes
> in latest 2 month than in my 15 years by using ext[[2-4]
> 2) ZFS has native bit-rot protection and data scrubbing

So does gluster

> 3) ZFS has de-duplication and compression

dedup requires massive amounts of memory and is seldom worth it.

> 4) In case of hardcrash, try to run a XFS fsck on a server with 12x
> 8TB disks..... Probably you need a week or more. on our backup server
> (8TB raid-6) it took 18 hours.
Which is why I don't like building raid volumes that large.

Personally, I only use raid on the servers to allow the disk i/o to 
match the network i/o. If that means those 12 8TB disks need to be 3 
raid 0 volumes (bricks) where I do sharded replica 3 or disperse volumes 
to meet my redundancy requirements, then that's what I'll do.

This is where people panic about using raid 0. If you've got the 
redundancy, that shouldn't be that scary. Do the math and actually 
calculate your reliability. I can still get 6 nines with raid 0 bricks. 
Not to say you should use raid 0, just to keep an open mind about what 
possibilities exist and engineer to your SLA requirements rather than 
over engineering for things that may not matter in the long run.