New Home Build Recommendation

[suhlhorn]

Hello-

New to FreeNAS, but not to storage servers in general. 'Back in the day', I put together a bunch of linux raid+lvm systems using spare parts and *never* had a problem using old junk.

However, I had a recent *near loss* of all our baby photos (my wife almost killed me!) using "the best desktop backup solution". Nevertheless, I decided it was time to make a *real* NAS using FN for a home backup+file server. I knew I wanted a ZFS based system. I dug through my old hardware and decided I had enough parts to put a machine together. Then I started reading the docs and forums...

SO... New plan. I'm going to build a machine from *mostly* new hardware:
Supermicro X10SL7
Xeon E3-1220V3 (Haswell)
Crucial 2x8Gb ECC UDIMM (yes, I read the ECC threads (and the X10 mem thread) )
4x 4TB WD Reds

My plan is/was to make a 4-disk RAIDZ2 vdev for the pool. But as I considered how to backup the pool, I wasn't sure this was the best plan since ~50% of the pool is primarily used for backup from desk/laptops. The other ~50% will be used for file storage that would be the primary data destination (personal files, pictures, movies, etc). Given that I want to use the pool for both backup and primary storage purposes, what is the best way to allocate the disks?

My first thought was to use a 4-disk (Z2) vdev for all storage and then make another striped vdev that can hold replicated snapshots from the Z2 array. That way, I could continually add disks to the snapshot vdev to to accommodate the growing size. Maybe this vdev will be in the same pool as the Z2 vdev at first, or perhaps it will be migrated to an offsite system if necessary. Is this dumb?

Then, I thought that maybe the best use of the space was to simply make a RAID10 system, ie- 2 striped disks that are mirrored to the other 2 striped disks. Considering that this is meant for a home server and that my storage requirements are small compared to the 16TB in disk space, perhaps this makes more sense from a redundancy/safety standpoint?

I think I have a pretty good grasp of the principles of ZFS, but need a little guidance with the details. I would rather spend some more time planning up front, rather than have to redo the whole system later. If my primary objective is have a 'cosmic-ray' proof storage box, then:

1) Does RAID10 (ZFS-mirrored-stripes) make more sense than RAIDZ2 with replicated snapshots?

2) Do I need to have the snapshot backup vdev (or mirrored array) in another box? Off-site?

Any insight you can offer will be appreciated. I am still learning and open to [constructive] criticism.

Thanks-
-stephen

 

[Robert Trevellyan]

1. ZFS doesn't do mirrored stripes. It does striped mirrors, but that doesn't give you additional redundancy. RAIDZ2 is more reliable than striped mirrors for four disks.
2. Depends on what types of risks you want to mitigate. Accidental deletion? Hardware failure? Fire/theft?

 

[anodos]

Don't forget about backups. A few guidelines:

• Even the best designed system will fail one day.
• If you only have one copy of your data, you don't have a backup.
• If you never test restoring your data, you probably don't have a usable backup.
• You can never have too many backups.

 

[suhlhorn]

OK Thanks-

I think I get it. After reading a little more about replication, it sounds like the best method would be to have an off-site fNAS to hold replicated snapshots.

If I setup the off-site pool to be a simple striped array allowing me to grow it as needed, what is the size requirement to start? Does a snapshot require the same amount of space as the size of the entire Z2 pool? Or, just the size of the data in the pool?

Thanks-
-stephen

 

[Ericloewe]

OK Thanks-

I think I get it. After reading a little more about replication, it sounds like the best method would be to have an off-site fNAS to hold replicated snapshots.

If I setup the off-site pool to be a simple striped array allowing me to grow it as needed, what is the size requirement to start? Does a snapshot require the same amount of space as the size of the entire Z2 pool? Or, just the size of the data in the pool?

Thanks-
-stephen

Replication only needs to be able to fit the replicated snapshots.

So, you'd need 5TB (plus overhead - 80% rule, etc.) on the destination server if you had 5TB on the sender, even if the sender is a 100TB pool.
There are details that change this slightly, but you can count on that as a rule of thumb.

 

[Robert Trevellyan]

If I setup the off-site pool to be a simple striped array

For your backups? The last-resort, when all else fails, and no redundancy?

 

[David Dyer-Bennet]

You have to have your backups in another box. In act, in another building. Otherwise, a fire, flood, or burglary can easily deprive you of both.

In general, any situation which has both the real data and the backup online on the same system at the same time is suspect. In the old days, doing rotating tape backup sets, the set currently being written was never considered a backup; that was scratch tapes being made into a backup, and there had to be at least one actual backup somewhere!

 

[suhlhorn]

Thanks for the pointers.

I'm sure I'll have more questions as the boxen get built.

-stephen

 

[suhlhorn]

Quick update....

I got freeNAS installed and I'm starting to configure my pool. I followed the recommended HW guidelines and everything "just worked". AMAZING!

Super X10SL7-F/Xeon E3 1220v3/2x8G Crucial ECC UDIMM

4x4TB WD Reds for RAIDZ2 pool
2xSSD mirrored for fNAS (I had them already!)

Jut want to say thanks to everyone here for supporting such a great system!
-stephen