Need Help setting up (planning) NAS

[pcace]

Hi there,

i am completely new here, and hope i am not a the wrong spot to ask my questions. furthermore, i am sorry for my english, its not my mainlanguage.

A week ago my old QNAP NAS (for home and office file storage)released some smoke and just died. So now i am looking for a new solution. My new machine is a Core i5 / 8GB DDR3 Ram machine, wich will serve as my new NAS. First of all there are a few things it must be able to do/have:
- work as backuplocation for a debian mailserver (every night an incremental backup via rsync)
- work as backuplocation for 3 Macs with around 5TB space (timemachine)
- and a SMB file location for 5 users

The machine has now 4x 4TB HDD + 1x 8TBHDD + 1x SSD.
My Idea now is to use the 1x8TB as SMB File storage location (one partition) and then the 4x4TB as backuplocation as a RAID5.
There i would put Timemachine, Serverbackup + Backup of the 8TB Disk onto it. The 256GB SSD would be the System Disk.

Firtst of all: is this plan ok? or would it make more sense to make one big raid out of all disks and then put Backup and Data in the same Raid?

What would be a modern approach to this?

Any hint or idea would be great!!

Thank you so much,

pcace

 

[Arwen]

First, TrueNAS does not support RAID-5. ZFS does support a similar concept called RAID-Z1, but that is not recommended for disks larger than 1TB or 2TB. For larger disks, it is recommended to use RAID-Z2, which is similar to RAID-6 in that their are 2 disks worth of redundancy.

You should read up on ZFS and use the right terminology:

Terminology and Abbreviations Primer

We realize that new users have a lot to learn when they come to FreeNAS. There's a certain amount of confusion added to discussions when users pick random/approximate terms to describe things. I've spent a lot of time quietly trying to...

www.truenas.com

Next, most TrueNAS installations use redundant configurations for the primary storage. Thus, your 8TB lone drive could get unrecoverable errors.

Further, it's not really a good idea to use 4 x 4TB disks & 1 x 8TB disk in a single ZFS pool, as half the 8TB disk is wasted.

Last, you might want to list some more details of your computer that you would like to use for TrueNAS. Some gaming or desktop boards have less than ideal network chips which reduce performance noticeably.


ZFS, (used exclusively for storage on TrueNAS), does things differently than most RAID schemes, (software or hardware). So it's best to read up and make sure TrueNAS meets your needs.

 

[pcace]

Hi,

thank you so much for your very informative reply!! Reading my question again i feel like i really showed how little i know about TrueNAS and ZFS.
let me make it a little bit more precise after reading a little bit into ZFS and its capabilities:

there would be the 1x8TB pool (does one call it pool too when there is only one physical device? or is that even possible?) wich would be the actual storage for users. Yes - without any redundancy. This 8TB HDD would be then backupped to the 4x4TB pool as a replication.
On the 4x4TB pool there would also be the timemachine backups and serverbackups from my mailserver.

So in the end, the only "usable" space for users in the network would be the 1x8TB pool via SMB share.
If this disk failes, there would be a replication on the 4x4TB pool wich i would use as a backup.

Does that make more sense?

The Mainboard has a RealTek RTL8111G controller. Wich of what i read here is not a nice option, but still - i am only going to use the machine for very low performance applications - so wouldnt it be enough?

And one more question to the RAID-z2 / RAID-Z decision - what would be the advantage (besides even better redundancy) from Z2 over Z?
Isnt the advantage only the there can be two disks wich can fail?

Thank you so much for your Time and sorry for all these very basic questions!!

 

[pcace]

Since there seems to be no EDIT button here in the Forum i just place one more question here.
If my plane makes some sense, i would then plan to use the replication and its snapshots as a backup. My idea would be to make a snapshot every lets say week and keep them for 3 Years for example. Is this a valid use case?
Thanks again!!

 

[Arwen]

Yes, a single disk can be a ZFS "pool". I used such on my old laptop.

Yes, you can have your 8TB disk, (without redundancy), as your main SMB share.
And you can copy / replicate it to the other pool of 4 x 4TB disks.

The big reason to use RAID-Z2 over -Z1 is that during a disk replacement, statistically a second disk could exhibit an error. This could cause loss of file data, (unless it's in metadata, see below).

Some RealTek network interface chips don't just have lower performance, they can and do lockup. Either loading or odd corner cases of driver actions. This may force you to reboot. How often? We would not know... Some people would just "blame" TrueNAS and force a reboot.


Many recommendations are made to improve reliability. Using TrueNAS, (and then ZFS), comes with limitations as well as suggestions. Some people who don't follow the limitations or suggestions end up with less than ideal, or even unreliable NAS servers.

If those users come back to the forums and ask why that had problems, sometimes it's something new we need to address. But, most of the time it's a known limitation of either TrueNAS or ZFS. Or not following recommended hardware or best practices.

One new issue that came up in the last year or so, is using SMR, (Shingled Magnetic Recording), drives. These are 100% NOT suitable for ZFS. That said, I use 2 with ZFS and live with the limitations and problems. But, I also have not asked for help on why they act the way they do...


Basically I am saying if you use the 8TB disk as a single disk pool, you will need to deal with any errors that come up. Most people here in the forums don't use single disk pools, so any response will likely be restore from backups.

In essence, you may find TrueNAS with ZFS less reliable or require more hands on, than a QNAP or Synology NAS, if TrueNAS is not setup well.

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Note that ZFS metadata, (directory information, etc...), always has at least 2 copies, irregardless of the pool's redundancy. ZFS took the approach that metadata is more important than file data. Thus, even on a single disk pool, their are 2 copies of metadata. Of course, in general metadata is a pretty small percentage of used disk space compared to file data. (The exception is when a user stores tons of tiny files...)

Normal file systems have 1 copy of metadata, which if lost, you loose some or all of the file data too.

ZFS critical metadata has 3 copies, again irrespective of the pool's redundancy.