How to limit SATA link speed?

[ajp_anton]

I’m having problems with HDD transfer errors, and I’d like to troubleshoot by limiting the SATA link speed. The signals go through a hotswap backplane, which might be built with SAS in mind with its support for longer cables? Who knows, but I’m fine with not having 6Gbit speeds.

I’ve tried the command
midclt call system.advanced.update '{"kernel_extra_options": "libata.force=1.5Gbps"}'
and it does put this parameter into the grub file, and it does survive a reboot.

But smartctl -i /dev/sdX still reports
SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)

What am I doing wrong?

[SmallBarky]

Really need your hardware, software and pool setup details

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[ajp_anton]

I have two completely different systems:

• Main system, which has the transfer errors. I don’t want to play around here unnecessarily. Tried it once, didn’t work, moved on.
• Secondary system, which doesn’t have errors. I don’t mind tinkering with this, so I’m trying to figure this out here first before trying on the main system.

So since I’m now trying this on the secondary (and simpler) system, here’s its info:

Hardware:
Four spinning SATA drives connected to an IBM M1215 controller in IT mode, so it acts as a dumb HBA. No backplanes on this system, just direct connections from HBA to drives. Boot and app drives are virtual drives.

Software:
Proxmox → TrueNAS 24.10.0.2, the whole HBA being passed through so TrueNAS has full control over it and the drives.

Pool setup:
Not sure what’s being asked here, but the main storage pool has all of those drives in one RAIDZ1 vdev.

[SmallBarky]

You will have to provide details on the one with the problems and may be asked to run commands and post the results back.

Provide details on all the hardware, software setup of Proxmox, how drives are attached (you mentioned HBA passthrough in Proxmox) , drive models (looking CMR vs SMR tech, other issues).

Proxmox is a cause of a lot of problems with TrueNAS.

[ajp_anton]

This secondary system doesn’t have the transfer issues, but it does have the same problem of not being able to limit the SATA link speed. Once I find a solution on the secondary system, I can try applying that to the main system, but I’m not there yet. Only reason to even mention the main system was to motivate the reason behind limiting the speed.

The main system is kind of the same, just more complicated. More VMs in Proxmox, more passed through HBAs, more drives, backplanes between the HBAs and the drives, metadata vdevs… just more hardware in general. Even from that perspective it’s easier to troubleshoot on the slightly simpler system first, because it’s having this same issue with limiting link speeds.

So, back to the secondary system, where I’m currently trying to solve this. Proxmox is version 8.2.7, it has two other VMs: pfSense and Home Assistant. It has no control over the drives in question, as they are connected through the HBA, which is being passed through to TrueNAS. Drives are Toshiba MG10 20TB, I’ve made sure to avoid at least SMR.

I know running TrueNAS in a VM is not recommended, but here TrueNAS should have full control over the HBA, the drives, and all SATA related stuff inbetween.