Currently have two mechanical 14TB drives (neither SMR) with one data and one parity. Doing a new build, something a tiny bit more power efficient than my Z420. Going to replace one of the 14TB drives with a 15.36TB U.2 SSD. Don't worry, I've already been told that I should under no circumstances use an SSD as a drive in an unRAID array, but I'm going to anyway 😀

 

Currently using xfs, but I'd really, REALLY like to have native snapshot support. I figure now is as good a time as any to change filesystems, so, what would you do?

 

Switch to the new hotness ZFS, because it's new and awesome and features!!!!

Switch to BTRFS. It's not as flashy, but it is a bit more mature...at least when it comes to unRAID support.

Stay with XFS, snapshots are for wimps!

 

I wouldn't be looking to setup a ZFS pool as cache, so I know that a lot of ZFS's awesomeness would be lost on my setup (just a single drive/vdev in an array, plus a mechanical drive for parity). I also don't need ZFS's ability to eat RAM to speed up access, since the data drive would be an enterprise ssd. Yes, writes would be abysmally slow, but that hasn't been a concern yet (read speeds are another issue, I'm having the infamous MacOS smb issues, but I've stopped messing with that until the new system is up and running).

 

One minute I'm leaning ZFS because it really was made for this, even if I'm severely limiting its potential; the next minute I'm leaning toward BTRFS because I envision much lower system resource usage and better overall stability (not because BTRFS is better than ZFS, but because there's been more time to work out the kinks between unRAID and BTRFS). Or perhaps I should just rip out the old data drive, throw in the new U.2 drive, do a rebuild, and ask again next decade.

Edited January 11, 20242 yr by josetann

Both zfs and btrfs are good options, but note that currently there's an issue affecting zfs write performance when used in the array, it does not affect pools.

 

 

My extremely biased opinion is that, within the unRAID array, zfs provides no benefits over BTRFS. The only time I would suggest using zfs on an array disk is if you are making use of zfs cache pools and want to be able to easily send snapshots between the pool and arrays. 

Edited January 11, 20242 yr by primeval_god

Back when Unraid added BTRFS and XFS file systems it was recommended to use XFS for the array disks.  Is this this recommendation no longer valid?

XFS is still a valid option, and if you don't care about snapshots, send/receive, checksums, etc, might as well keep using it.

Ok thanks.  I was under the impression there was corruption issues at one time with BTRFS in the array.

Btrfs usually is not a problem on the array, since they are single device filesystem, 95% of my array disks are btrfs for like 6 years or more and never had a problem, it can be more of a problem with multi device pools if used with unreliable hardware and users don't monitor them for errors, or if there are RAM issues, btrfs is also very susceptible to bad RAM, much more than XFS.

11 hours ago, JorgeB said:

Both zfs and btrfs are good options, but note that currently there's an issue affecting zfs write performance when used in the array, it does not affect pools.

 

Do you know if it's slow relative to the disk speed, or just slow period? Since the data drive would be an nvme ssd, slow relative to the disk speed may still be faster than the mechanical parity drive can handle.

 

2 hours ago, Gragorg said:

Back when Unraid added BTRFS and XFS file systems it was recommended to use XFS for the array disks.  Is this this recommendation no longer valid?

It may still be the recommendation. I've had literally zero problems using xfs, I have no problem recommending it. I just really like the idea of being able to take snapshots (I had a nightmare where one of my family members who knew better, clicked something they shouldn't and now everyone's mad at me because I should have known about ransomware). I've been a bit lazy when it comes to proper backups, snapshots would help mitigate some of the risk that's a result of said laziness. Plus it's cool, I like cool.

2 hours ago, JorgeB said:

Btrfs usually is not a problem on the array, since they are single device filesystem, 95% of my array disks are btrfs for like 6 years or more and never had a problem, it can be more of a problem with multi device pools if used with unreliable hardware and users don't monitor them for errors, or if there are RAM issues, btrfs is also very susceptible to bad RAM, much more than XFS.

I've read about issues with btrfs, but haven't seen anything saying WHY. I've only used btrfs in a proxmox setup with two 1TB NVME drives in a mirror, with unRAID I've only used xfs (except when unRAID was ReiserFS only, but we don't talk about that).

 

So you're saying that if I use at least somewhat quality hardware (currently using enterprise drives, I have used SMR consumer drives in the past though) and have ECC RAM (so shouldn't have ram issues), I shouldn't have the issues others are reporting with btrfs? Do you think it's more reliable than zfs with semi-quality hardware?

Edited January 11, 20242 yr by josetann

12 hours ago, josetann said:

Do you know if it's slow relative to the disk speed, or just slow period? Since the data drive would be an nvme ssd, slow relative to the disk speed may still be faster than the mechanical parity drive can handle.

Relative to the disk speed, issue only shows when the source is faster, more info here:

https://forums.unraid.net/bug-reports/prereleases/zfs-write-speed-issue-array-disk-no-parity-on-6120-rc6-r2414/

 

12 hours ago, josetann said:

Do you think it's more reliable than zfs with semi-quality hardware?

I would still consider zfs more robust for pools, for single device filesystem they should be more close together, and yes, with ECC RAM and decent quality hardware there shouldn't be any issues.

On 1/11/2024 at 10:13 AM, JorgeB said:

Both zfs and btrfs are good options, but note that currently there's an issue affecting zfs write performance when used in the array, it does not affect pools.

 

 

Has this been resolved already? Running Unraid 7 RC1

46 minutes ago, TallMan206 said:

Has this been resolved already? Running Unraid 7 RC1

If you mean the performance issue for ZFS in the main array then I do not believe so.   

It may not be soluble if it is due to an interaction between the way ZFS works and the way the main array handles parity.

1 hour ago, TallMan206 said:

Has this been resolved already?

Not yet, it may not be an easy fix, it's related to how zfs interacts with the md driver.