What drives? If they are shingled, your performance will be terrible and the array runs a high risk of failing.
CMR is the way to go.
SMR behavior is about like what you describe... Fast until the drive cache is filled then plummets to nothing.
this post was submitted on 14 Mar 2025
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5 are WD HC530 datacenter drives and two are the 14TB EZAZ from Easystores. I don't think any of the larger WD drives are SMR but I don't have a definitive answer.
Hmm, at a glance those all look to be CMR.
To rule this out ideally, a tool like iostat (part of sysstat tools) can help. While moving data, and with the problem happening, if you run something like "iostat 1 -mx" and watch for a bit, you might be able to find an outlier or see evidence of if the drives are overloaded or of data is queueing up etc.
Notably watch the %util on the right side.
https://www.golinuxcloud.com/iostat-command-in-linux/ can help here a bit.
The %util is how busy the communication to the drive is.. if maxed out, but the written per second is junk, then you may have a single bad disk. If many are doing it, you may have a design issue.
If %util doesn't stay pegged, and you just see small bursts, then you know the disks are NOT the issue and can then focus on more complex diagnosis with networking etc.
Thinking the same here.
Does the Proxmox host have the driver installed for your 2.5Gb NIC? Can't use it if it's not installed. Connect to the host and run ethtool <device>. Should show the link speed as Speed: .
I have roughly 40TB of media to transfer and 8MB/s isn’t going to cut it.
If you need ultra-speed data, why not do a 100GbE switch with JBOD? 40TB isn't a small amount of data. Generally no matter what setup you have it's going to take a significant amount of time to swap data here.
I haven't installed any drivers on the Proxmox machine. That one has the 2.5Gb NIC built into the motherboard so I probably misspoke when I called it a "card" in the OP if that makes a difference. I'll try this when I get home but I have run 'lspci' and it shows the NIC on both the host and container (Intel Killer 3100 2.5Gb though it's listen as Killer 3000 2.5Gb) plus my iperf3 tests were showing ~2.3Gb speeds between both machines and the container.
As far as the 100GBe switch, I only need to transfer the media off the old machine once so I was just trying to go with something inexpensive since the standard 1Gb ethernet should be fine for most things after this initial transfer.
Linux doesn't have drivers like Windows does. The kernel either supports the hardware or it doesn't.
This is categorically untrue. The kernel includes most open source drivers however it does not include proprietary drivers (or even all open source drivers) which require recompiling the kernel itself or installing secondary headers...
I've used many networking cards in the past that required you to recompile the kernel for them to work properly...
I, like you, will be migrating from Windows to ProxMox soon. Can you give a link to the guide you mentioned?
Can you do a speed test of your zpool?
dd if=/dev/null of=<mount-point>/test.file bs=1G count=10 status=progress
Better to use iostat
zpool iostat
dd if=/dev/null of=/test.file bs=1G count=10 status=progress
/dev/null tests from dd are not an accurate indicator of performance unless you only have one disk in your pool. fio is a much more accurate tool for zfs pool testing.
How much RAM your system has? Zfs is pretty hungry for memory and if you don't have enough it'll have quite significant impact on performance. My proxmox had 7x4TB drives on zfs pool and with 32 gigs of RAM there was practically nothing left for the VMs under heavy i/o load.
I switched the whole setup to software raid, but it's not offically supported by proxmox and thus managing it is not quite trivial.
ARC will give way to other memory uses. Were you actually seeing memory shortage or did you just see the usage and think that you couldn't overprovision?
Actual shortage. Performance drops significantly when zfs doesn't have enough memory. It might have been an option to tweak configuration for zfs pools, add SSD for caching and so on, but I needed to change drive configurations anyways for other reasons so for me it was easier to drop zfs and switch to software raid.
Lots of variables here, we would need to pare them down:
- architecture of zfs pool? This can be done well or very poorly, zfs gives you a lot of rope, if you know what I mean.
- memory?
- have you tuned samba ?
- are you trying to do anything fancy like jumbo frames ?
- what networking equipment lies between the two?
- do you have the correct and correctly configured 2.5gb driver for linux ? Intel 2.5 NICs had some issues for a while.
- what does the windows net hardware look like?
In troubleshooting transfer speeds , there are solo many variables, as you can see.
Start with the network and reduce variables until you have a likely source of the problem.
What's your throughput to another Windows box from your source machine? Samba isn't known as a fast transfer protocol. You could also try NFS services on the windows box and export your shares to try that.
You might also enable jumbo frames if it's a lot of larger files.
I don't know about the Ubuntu LCX. I don't container much.
I'd do this with a virtual machine and TrueNAS. Those are just the tools I like to use.
The TrueNAS Scale ISO will install qemu-guest-agent, so you don't need to worry about drivers.
Make sure to build it with Virtio SCSI Single disk controllers.
Use one 50gb OS disk for the install. Add huge data disk(s) after the install.
Promox Disk options ... SSD emulation, Discard, IO Thread, No cache ... and I use Write Back (unsafe).
Use the Virtio NIC.
And try it again. Hopefully faster this time.
What's the benchmark on the disks? Are these SAS drives?