Setting up new NAS

[kingston12]

I’ve just bought a new Synology DS918+ NAS and am trying to work out the best way to set it up.

It has got four 10TB hard drives inside, and my plan was to run them as two pairs with one drive as a back up of the other, and then use the USB port to back up to external drives which I’ll keep elsewhere.

The Synology OS doesn’t seem to have the option to set it up like that. I can combine two 10TB disks into one volume using SHR, but:

1. This only gives me 8.7TB capacity (the drives are recognised as 9.1TB before SHR)

2. Isn’t SHR just a type of RAID and therefore not as good as a real backup?

Any advice appreciated!

[bitchstewie]

You're correct that RAID (traditional or SHR) is not backup, RAID is redundancy, and depending on the type of RAID a way to improve performance.

With 4 drives I'd simply go with a single RAID10.

[thebraketester]

Set all four of them up as raid and then backup to external.

SHR I believe makes future HD expansion easier.

[mikef]

As you’re prepared to run mirrors and trade off capacity for resilience, then I’d definitely set up as RAID 10 (striped mirror). SHR is RAID 5 with some flexibility around different disk capacities.

The problem with RAID 5 with this capacity of disk is that (as you are about to find out), your 10TB disks will take the best part of a day to initialise. If a disk fails, and you slot in a replacement, the remaining disks will be hammered for a day to rebuild the RAID array. That hammering is the single thing most likely to cause a second disk to fail, at which point you have total data loss within the NAS unit

Having said that, I run two 4-disk Synology units, one in RAID 10 and the other (where I can live with total data loss) in SHR