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submitted 9 months ago* (last edited 9 months ago) by [email protected] to c/[email protected]
 

A year ago I set up Ubuntu server with 3 ZFS pools on my server, normally I don't make copies of very large files but today I was making a copy of a ~30GB directory and I saw in rsync that the transfer doesn't exceed 3mb/s (cp is also very slow).

What is the best file system that "just works"? I'm thinking of migrating everything to ext4

EDIT: I really like the automatic pool recovery feature in ZFS, has saved me from 1 hard drive failure so far

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[–] [email protected] 36 points 9 months ago* (last edited 9 months ago) (1 children)

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?

[–] [email protected] 3 points 9 months ago* (last edited 9 months ago) (1 children)

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

[–] [email protected] 7 points 9 months ago (2 children)

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.

[–] [email protected] 2 points 9 months ago* (last edited 9 months ago) (2 children)

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:

  • Performance is better than even RAIDZ2, especially as individual disk size increases.
  • Fault tolerance is better as you could have up to 50% of the disks fail, so long as one disk in a mirrored set remains functional.
  • Fault recovery is better. With traditional arrays with distributed chunks, you have to resilver (rebuild) the entire array, requiring more time, costing performance and shortening the life of the unaffected drives.
  • You can stripe mismatched sets of mirrored drives, so long as the mirrored set is identical, without having the array default to the size of the smallest member. This allows you to grow your array more organically, rather than having to replace every drive, one at a time, resilvering after each change.

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.

[–] [email protected] 1 points 9 months ago* (last edited 9 months ago)

Thanks for all the help!

I don't have any redundancy, my system has an SSD (the one being slow) and 2 500Gb HDDs, in the hdds I only have movies and shows so I don't care is that goes bad.

I have a lot of important personal stuff in the SSD but is new (6 months old) from crucial and I trust that because I don't have the money to spare on another drive (+ electricity bills) and I trust that I'll only lose 1-2 files if it goes bad because of the ZFS protection

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[–] [email protected] 27 points 9 months ago (4 children)

Ext4 does not have snapshots, COW or similar features. I am very happy with BTRFS. It just "works" out of the box.

[–] [email protected] 14 points 9 months ago (2 children)

I use BTRFS on everything too nowadays. The thing that made me switch everything to BTRFS was filesystem compression.

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[–] [email protected] 6 points 9 months ago (1 children)

FWIW lvm can give you snapshots and other features. And mdadm can be used for a raid. All very robust tools.

[–] [email protected] 6 points 9 months ago (1 children)

Yes but BTRFS can this out of the box without extra tools. Both ways have their own advantage, but I would still prefer BTRFS

[–] [email protected] 4 points 9 months ago (1 children)

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/


_ /\ _

[–] [email protected] 1 points 9 months ago

Never had problems, but I wish you all the best for your ZFS problem 🤗

[–] [email protected] 3 points 9 months ago (12 children)

Yes and BTRFS, unlike Ext4, will not go corrupt on the first power outage of slight hardware failure.

[–] [email protected] 5 points 9 months ago

Wut? Ext4 is quite reliable.

[–] [email protected] 3 points 9 months ago

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.

[–] [email protected] 2 points 9 months ago

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.

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[–] [email protected] 16 points 9 months ago (1 children)

3mb/s sounds more like there is something else going on.

[–] [email protected] 3 points 9 months ago (1 children)

Yeah, but I don't know how to diagnose it...

[–] [email protected] 3 points 9 months ago (1 children)

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.

[–] [email protected] 2 points 9 months ago

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.

[–] [email protected] 11 points 9 months ago (2 children)

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.

[–] [email protected] 4 points 9 months ago

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.

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[–] [email protected] 9 points 9 months ago (2 children)

XFS has "just worked" for me for a very long time now on a variety of servers and desktop systems.

[–] [email protected] 1 points 9 months ago (1 children)

Careful as it is obscure enough that you could blow off your leg.

[–] [email protected] 4 points 9 months ago (1 children)

I don't see how the default filesystem of the enterprise Linux distro could be considered obscure.

[–] [email protected] 1 points 9 months ago (1 children)

I don't believe that XFS is the default for anything these days. I could be wrong though.

[–] [email protected] 1 points 9 months ago* (last edited 9 months ago) (3 children)

Default since RHEL 8. Consider looking up such facts before posting wrong facts.

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[–] [email protected] 9 points 9 months ago (1 children)

How full is your ZFS? ZFS doesn't handle disk filling and fragmentation well.

[–] [email protected] 4 points 9 months ago (1 children)

Around 70% full with 10% fragmentation

[–] [email protected] 2 points 9 months ago

At around 70%, fragmentation issues start becoming apparent with ZFS IIRC. Though they shouldn't be this apparent.

[–] [email protected] 8 points 9 months ago* (last edited 9 months ago)

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]

[–] [email protected] 6 points 9 months ago

I host my array of HDD drives with btrfs, works well and is Linux native.

[–] [email protected] 5 points 9 months ago (2 children)

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/

[–] [email protected] 2 points 9 months ago (1 children)

From the article it looks like zfs is the perfect file system for smr drives as it would try to cache random writes

[–] [email protected] 2 points 9 months ago

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.

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[–] [email protected] 5 points 9 months ago* (last edited 9 months ago)

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.

[–] [email protected] 5 points 9 months ago (2 children)

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.

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[–] [email protected] 4 points 9 months ago (1 children)

ZFS should have better performance if you set it up correctly.

[–] [email protected] 4 points 9 months ago (3 children)

That's exactly their gripe: out of the box performance.

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[–] [email protected] 4 points 9 months ago (1 children)

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...?

[–] [email protected] 1 points 9 months ago (1 children)

Same NAS, same filesystem on an SSD without redundancy

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[–] [email protected] 2 points 9 months ago

Use zfs sync instead of rsync. If it's still slow, it's probably SMR drives.

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