Comment on [Question] Alternative to NFS for Proxmox Backup Server
pyrosis@lemmy.world 5 months agoSo you mentioned using proxmox as the underlying system but when I asked for proxmox filesystem I’m more referring to if you just kept the defaults during installation which would be lvm/ext4 as the proxmox filesystem or if you changed to zfs as the underlying proxmox filesystem. It sounds like you have additional drives that you used the proxmox command line to “passthru” as scsi devices. Just be aware this not true passthru. It is slightly virtualized but is handing the entire storage of the device to the vm. The only true passthru without a slight virtualization would be pci passthru utilizing IOMMU.
I have some experience with this specifically because of a client doing similar with a truenas vm. They discovered they couldn’t import their pool into another system because proxmox had slightly virtualized the disks when they added them to vm in this manner. In other words zfs wasn’t directly managing the disks. It was managing virtual disks.
Anyway, it would still help to know the underlying filesystem of the slightly virtualized disks you gave to mergerfs. Are these ext4, xfs, btrfs? mergerfs is just a union filesystem that unifies storage across multiple mountpoints into a single virtual filesystem. Which means you have another couple layers of complexity in your setup.
If you are worried about disk IO you may consider letting the hypervisor manage these disks and storage a bit more directly. Removing some of the filesystem layers.
I could recommend just making a single zfs pool from these disks within proxmox to do this. Obviously this is a pretty big transition on a production system. Another option would be creating a btrfs raid from these disks within proxmox and adding that mountpoint as storage to the hypervisor.
Personally I use zfs but btrfs works well enough. Regardless this would allow you to just hand storage to vms from the gui and the hypervisor would aid much more efficiently with disk io.
As for the error it’s typically repaired by unmount mount operations. As I mentioned before the cause can be various but usually is a loss of network connectivity or an inability to lock something down in use.
My advice would be to investigate reducing your storage complexity. It will simplify administration and future transitions.
Repost to op as op claims his comments are being purged
brownmustardminion@lemmy.ml 5 months ago
Thanks so much for the detailed reply. I have about 20TB of data on the disks otherwise I would take your advice to set up a different scheme. Luckily, as it’s a backup server I don’t need maximum speed. I set it up with mergerfs and snapraid because I’m essentially recycling old drives into this machine and that setup works pretty well for my situation.
The proxmox host is the default (ext4/lvm I believe). The drives are also all ext4. I very recently did a data drive upgrade and besides some timestamp discrepancies likely due to rsync, the SCSI semi-virtualized thing wasn’t an issue. I replaced the old drive with a larger one, hooked the old one up to a usb dongle and passed it through to OMV and I was able to transfer everything and get my new data drive hooked back into the mergerfs pool and snapraid. I’ll do a test and see if I can still access the files directly in the proxmox host just for educational purposes.
I’ll try to re-mount the NFS and see where that gets me. I’m also considering switching to a CIFS/SMB share as another commenter had posted. Unless that is susceptible to the same estale issue. I won’t be back at that location for about a week so I might not have an update for a little while.