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ZFS is a very robust choice for a NAS. Many people, myself included, as well as hundreds of businesses across the globe, have used ZFS at scale for over a decade.
Attack the problem. Check your system logs, htop, zpool status.
When was the last time you ran a zpool scrub? Is there a scrub, or other zfs operation in progress? How many snapshots do you have? How much RAM vs disk space? Are you using ZFS deduplication? Compression?
I don't even know what a zpool scrub is lol, do you have some resources to learn more about ZFS? 1TB pool and 2 500GB pools, with 32GB of RAM, No deduplication and LZ4 compression
Yeah, you should be scrubbing weekly or monthly, depending on how often you are using the data. Scrub basically touches each file and checks the checksums and fixes any errors it finds proactively. Basically preventative maintenance.
https://manpages.ubuntu.com/manpages/jammy/man8/zpool-scrub.8.html
Set that up in a cron job and check zpool status periodically.
No dedup is good. LZ4 compression is good. RAM to disk ratio is generous.
Check your disk's sector size and vdev ashift. On modern multi-TB HDDs you generally have a block size of 4k and want ashift=12. This being set improperly can lead to massive write amplification which will hurt throughput.
https://www.high-availability.com/docs/ZFS-Tuning-Guide/
How about snapshots? Do you have a bunch of old ones? I highly recommend setting up a snapshot manager to prune snapshots to just a working set (monthly keep 1-2, weekly keep 4, daily keep 6 etc) https://github.com/jimsalterjrs/sanoid
And to parrot another insightful comment, I also recommend checking the disk health with SMART tests. In ZFS as a drive begins to fail the pool will get much slower as it constantly repairs the errors.
Adding on to this:
These are all great points, but I wanted to share something that I wish I'd known before I spun up my array... The configuration of your array matters a lot. I had originally chosen to use RAIDZ1 as it's the most efficient with capacity while still offering a little fault tolerance. This was a mistake, but in my defense, the hard data on this really wasn't distributed until long after I had moved my large (for me) dataset to the array. I really wish I had gone with a Striped Mirror configuration. The benefits are pretty overwhelming:
Yes, you pay for these gains with less usable space, but platter drives are getting cheaper and cheaper, the trade seems more worth it than ever. Oh and I realize that it wasn't obvious, but I am still using ZFS to manage the array, just not in a RAIDZn configuration.
Wow that's a lot of info, thank you!
Ext4 does not have snapshots, COW or similar features. I am very happy with BTRFS. It just "works" out of the box.
I use BTRFS on everything too nowadays. The thing that made me switch everything to BTRFS was filesystem compression.
Yes compression is cool. Zstd level 3 to 6 is very quick too 😋
I use zstd too, didn't specifiy a level tho, so it's just using the default. I only use like ⅔ of the disk space I used before and I don't feel any difference in performance at all.
FWIW lvm can give you snapshots and other features. And mdadm can be used for a raid. All very robust tools.
Yes but BTRFS can this out of the box without extra tools. Both ways have their own advantage, but I would still prefer BTRFS
I'm in BTRFS, and wish I wasn't.
Booting into a failed mdadm RAID1 is normal,
whereas booting into a failed BTRFS RAID1 requires competent manual intervention, and special parameters given to the boot-kernel.
mdadm & lvm, with a fixed version of ZFS would be my preference.
ZFS recently had a bug discovered that was silently corrupting data, and I HOPE a fix has been got in.
Lemme see if I can find something on both of these points..
https://linuxnatives.net/2015/using-raid-btrfs-recovering-broken-disks
https://www.theregister.com/2023/11/27/openzfs_2_2_0_data_corruption/
_ /\ _
Never had problems, but I wish you all the best for your ZFS problem 🤗
Yes and BTRFS, unlike Ext4, will not go corrupt on the first power outage of slight hardware failure.
Wut? Ext4 is quite reliable.
I've run btrfs for years and never had a issue. They one time my system wouldn't boot it was due to a bad drive. I just swapped the drive and rebalanced and I was back up and running in less than a half an hour.
Corruption on power only regularly happened to me on xfs a few years ago. That made me swear to never use that fs ever again. Never seen it on my ext4fs systems which are all I have for years in multiple computers.
This will also happen to Ext4. You just wouldn't know it.
I'm confused with your answer. BTRFS is good and reliable. Ext4 gets fucked at the slightest issue.
Never had an issue with EXT4.
Had a problem on a NAS where BTRFS was taking "too long" for systemD to check it, so just didn't mount it... bit of config tweaking and all is well again.
I use EXT* and BTRFS where ever I can because I can manipulate it with standard tools (inc gparted).
I have 1 LVM system which was interesting, but I wouldn't do it that way in the future (used to add drives on a media PC)
And as for ZFS ... I'd say it's very similar to BTRFS, but just slightly too complex on Linux with all the licensing issues, etc. so I just can't be bothered with it.
As a throw-away comment, I'd say ZFS is used by TrusNAS (not a problem, just sayin'...) and... that's about it??
As to the OPs original question, I agree with the others here... something's not right there, but it's probably not the filesystem.
3mb/s sounds more like there is something else going on.
Yeah, but I don't know how to diagnose it...
You could try to redo the copy and monitor the system in htop, for example. Maybe there's a memory or CPU bottleneck. Maybe one of your drives is failing, maybe you've got a directory with tons of very small files, which causes a lot of overhead.
Yes, file size, drive types, the amount of RAM in the server, in the source and destination of the operation, can all have an effect on Performance. But generally if he’s moving within the same pool, it should be pretty quick.
Most filesystems should "just work" these days.
Why are you blaming the filesystem here when you haven't ruled out other issues yet? If you have a drive failing a new FS won't help. Check out "smartctl" to see if it reports errors in your drives.
they may be using really slow hard drives or an SSD without DRAM.
or maybe a shitty network switch?
maybe the bandwidth is used up by a torrent box?
there's a lot of possible causes.
How full is your ZFS? ZFS doesn't handle disk filling and fragmentation well.
Around 70% full with 10% fragmentation
At around 70%, fragmentation issues start becoming apparent with ZFS IIRC. Though they shouldn't be this apparent.
XFS has "just worked" for me for a very long time now on a variety of servers and desktop systems.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| LVM | (Linux) Logical Volume Manager for filesystem mapping |
| NAS | Network-Attached Storage |
| PSU | Power Supply Unit |
| SSD | Solid State Drive mass storage |
| ZFS | Solaris/Linux filesystem focusing on data integrity |
5 acronyms in this thread; the most compressed thread commented on today has 9 acronyms.
[Thread #486 for this sub, first seen 5th Feb 2024, 15:05] [FAQ] [Full list] [Contact] [Source code]
I host my array of HDD drives with btrfs, works well and is Linux native.
MergerFS + Snapraid is a really nice way to turn ext4 mounts into a single entry point NAS. OpenMediaVault has some plugins for setting this up. Performance wise it will max out the drive of whichever one you are using and you can use cheap mismatched drives.
ZFS is by far the best just use TrueNAS, Ubuntu is crap at supporting ZFS, also only set your pool's VDEV 6-8 wide.
Make sure you don't have SMR drives, if they are spinning drives. CMR drives are the I ly ones that should be used in a NAS, especially with ZFS. https://vermaden.wordpress.com/2022/05/08/zfs-on-smr-drives/
From the article it looks like zfs is the perfect file system for smr drives as it would try to cache random writes
Possibly, with tuning. Op would just have to be careful about reslivering. In my experience SMR drives really slow down when the CMR buffer is full.
It's an SSD, that's what worries me the most
ZFS should have better performance if you set it up correctly.
Where are you copying to / from?
Duplicating a folder on the same NAS on the same filesystem? Or copying over the network?
For example, some devices have a really fast file transfer until a buffer files up and then it crawls.
Rsync might not be the correct tool either if you're duplicating everything to an empty destination...?
Use zfs sync instead of rsync. If it's still slow, it's probably SMR drives.