Isn't there an option to mount an NFS share as read-only?

[mcx808]

I'm trying to mount a read-only NFS ISO store in PVE 8.1.4, however when trying to access this through the UI I get the error:
mkdir /mnt/pve/Images/template: Read-only file system at /usr/share/perl5/PVE/Storage/Plugin.pm line 1390. (500)

This is of course by design, I don't want PVE writing anything here, so how do I stop it?
I added options ro to my Images entry in /etc/pve/storage.cfg and I can actually ls /mnt/pve/Images and see the files, but it's not much use since the error appears whenever I try to attach an ISO to a VM.

Is there some way to achieve this?

 

[UdoB]

Is there some way to achieve this?

Workaround:

1) give PVE write access
2) establish the storage. It will create some folders, that's why it needs write access...
3) disable the storage
4) switch to readonly
5) enable the storage

You should be able to access those .iso's now in this state.

 

[mcx808]

It's read-only. So no write access at all, not even temporarily. Why does it need to create folders on a read-only volume and what are they for? Is it documented anywhere?

 

[BobhWasatch]

https://pve.proxmox.com/pve-docs/pve-admin-guide.html#storage_directory

See section 7.5:
We use a predefined directory layout to store different content types into different sub-directories. This layout is used by all file level storage backends.

There's a table that follows.

ETA: Maybe if you create the appropriate directory structure for the content type PVE won't try to write there.

 

[bbgeek17]

The other option is to create a "Directory" type storage pool. PVE will create the structure as described in the documentation provided by @BobhWasatch . Then, you can RO NFS mount the ISO storage to the "path/template/iso" subfolder directly.

Keep in mind that PVE does not, currently, recursively search for ISOs.

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[Kingneutron]

> Keep in mind that PVE does not, currently, recursively search for ISOs

https://github.com/kneutron/ansitest/blob/master/proxmox/symlink-samba-isos.sh

I got around that limitation by mounting a Samba share R/O and flat-mapping everything into /var/lib/vz with soft symlinks. Unless you have ISOs with the same name in different directories, should be able to adapt it to NFS - or even sshfs - fairly easily.

 

[mcx808]

https://pve.proxmox.com/pve-docs/pve-admin-guide.html#storage_directory

See section 7.5:
We use a predefined directory layout to store different content types into different sub-directories. This layout is used by all file level storage backends.

There's a table that follows.

ETA: Maybe if you create the appropriate directory structure for the content type PVE won't try to write there.

This works for preventing the write error, but the root NFS share is already called Images and already contains the ISOs, so none are recognised presumable because they're not in the /images subdirectory.

This is an ISO store accessed by many other types of OS, it's an odd design choice to try and force proxmox' folder structure preference on it.

 

[mcx808]

The other option is to create a "Directory" type storage pool. PVE will create the structure as described in the documentation provided by @BobhWasatch . Then, you can RO NFS mount the ISO storage to the "path/template/iso" subfolder directly.

Keep in mind that PVE does not, currently, recursively search for ISOs.

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

Thanks, after some experimentation I created the directory structure on my NFS store but symlinked templates/iso to .. on the actual NFS host. That way the NFS share can be defined in the Datacenter storage for all nodes but the ISOs in the root of my Images mount can be loaded by proxmox.