Mixed HDD setup in new TureNAS CORE build.

[kstarnicky]

I am turning my old VM Workstation/Plex server into a TrueNAS CORE server as I was just never using it and could use a NAS more. I need help deciding on what the best drive setup would be as I am using mixed drives.

System specs:
Xeon E5-2696v2 CPU
Chinese X79 mobo(cheap one from AliExpress)
64GB DDR3 ECC-Registered RAM
256GB NVMe boot drive
10G NIC connected to 10G switch
LSI SAS9211-8i HBA
450W Gold PSU
Fractal Design Node 804 case (10x3.5 HDD support plus 2x2.5" HDD/SSD)

Available drives:
1x 4TB Toshiba NAS 7200rpm HDD
1x 4TB HGST NAS 7200rpm HDD
4x 4TB Seagate Terascale 5900rpm Enterprise HDD
5x 3TB HGST NAS 7200rpm HDD
4x 3TB WD Red 5400rpm HDD

Also, I have a 5-bay USB 3.0 external enclosure that allows single drive access, so I presume I can just Raid those drives together and use it as a backup. I know, different system and/or offsite is best, but just can't do that at this moment. At some point I'll buy a 10GB or larger single drive external USB and use that as a secondary backup that I will keep offsite except to update it once every few months. The 5-bay enclosure can't handle the 7200rpm drives as they run too hot, so only the 5400rpm or 5900rpm drives can be put in there.

The NAS will have 2 primary uses. First is as a family NAS to safely store our personal files, mostly irreplaceable family pics. Second is to act as a centralized backup for all the PC's in the house. I want heavy redundancy & backup on the Family-NAS, but just basic redundancy and no backup for the Client-Backup. The client backup would have monthly writes to it from the various PC's doing a full backup once a month, but will do it on different days. The Family NAS won't be used that often, just when we need to add pics to it and look at them once in a while.

My initial thoughts on HDD setup is to create 3 pools, one on the USB enclosure for backups, one for the client backups, and one for the family NAS. The backup pool would be the 4x4TB Seagate Terascale HDD's in a RaidZ1 array for a total of 12TB(before formatting & ZFS overhead) of backup storage. The client backup pool would be 4x3TB WD Red also in a RaidZ1 array for 9TB(before formatting & ZFS overhead) of client backup storage. The main family NAS pool would consist of 3 mirrored Vdevs, so a pair of 2x3TB HGST NAS mirrors, and a 2x4TB HGST NAS mirror for a total of 10TB(before formatting & ZFS overhead) of highly redundant NAS storage.

I am not above purchasing a couple more drives as needed, but don't want to spend a ton on drives, so around $250 max. For that price, I could add 4 more 4TB Terascale drives, or two 4TB WD/Toshiba/HGST drives. but I really would prefer to not have to buy any at all.

Looking for opinions on my HDD setup and if it's not ideal, what other options would be. Any comments would help. Thank you.

 

[sretalla]

Available drives:
1x 4TB Toshiba NAS 7200rpm HDD
1x 4TB HGST NAS 7200rpm HDD
4x 4TB Seagate Terascale 5900rpm Enterprise HDD
5x 3TB HGST NAS 7200rpm HDD
4x 3TB WD Red 5400rpm HDD

Check each of those for exact model number against the known SMR list and throw those ones out of that box... use them for something else if you want, but not for ZFS.

List of known SMR drives

Hard drives that write data in overlapping, "shingled" tracks, have greater areal density than ones that do not. For cost and capacity reasons, manufacturers are increasingly moving to SMR, Shingled Magnetic Recording. SMR is a form of PMR...

www.truenas.com

 

[kstarnicky]

None are SMR according to that site.

 

[Yorick]

For family pic storage you do not need performance - Gig speeds are fine - and you can benefit from the additional redundancy of a raidz2 over mirror vdevs. You'd have a little less space, because you'd be limited to 3TB until the 3TB drives are replaced. If you can add two more drives, a 6-wide raidz2 is pretty optimal from a space/cost/redundancy perspective. But even 4-wide raidz2 gives you better redundancy than two mirror vdevs: In a raidz2, any two drives can fail; with two mirror vdevs, two drives in separate vdevs are allowed to fail.

I get the decision to have the backup pools with lower redundancy and a decent-sized risk of failure during rebuild. I agree that's fine for pure backup pools.

USB enclosures are generally a little tricky for ZFS use. This may work out, but be ready to move the backup pool into the main enclosure, which might require a case with sufficient mount points, and maybe an HBA.

And yes. Stay away from SMR at all costs.

 

[kstarnicky]

So you're recommendation is to switch my Family NAS pool from 3 mirrored Vdevs of 10TB to a single RaidZ2 Vdev of 12TB? I thought mirrors were MORE redundant than RaidZ2 even if you have several of them in a Vdev?

 

[Yorick]

Two-way mirrors are almost, but not quite as redundant as raidz2. Three-way mirrors are as redundant, but now you're giving up a lot of storage space.

Three two-way mirrors: Three drives can fail, but it has to be the right three drives: One per mirror. If two drives fail in one mirror, then you lost the entire pool. Others have done the math on this and came to the conclusion that mirrors are almost but not quite as resilient as a raidz2, assuming drives all fail at the same rate.

Raidz2: Any two drives can fail and the pool survives. Lose three drives and the pool is down. With raidz3, any three drives can fail.