[PVE-User] Shared ZFS storage that supports LXC's

Fiona Ebner f.ebner at proxmox.com
Tue Oct 31 10:20:33 CET 2023


Am 29.10.23 um 11:16 schrieb Bryan Fields:
> I do  get a warning in proxmox when moving a VM into it or making a
> snapshot:
> Warning: volblocksize (8192) is much less than the minimum allocation
> unit (32768), which wastes at least 75% of space. To reduce wasted space,
> use a larger volblocksize (32768 is recommended), fewer dRAID data disks
> per group, or smaller sector size (ashift).
> I can't find exactly what this is referring to or how to fix it.  Does
> anyone have insight into this message?

You can set the default blocksize in the storage configuration in
Proxmox VE, either in the UI (Block Size option) or via 'pvesm set <your
storage ID> --blocksize 32K'. Note that this will only apply to newly
allocated or moved volumes and not change existing ones.

> With the LXC's I've found they don't support this backend storage.  (and
> it's not mentioned in the docs) I assume this is do to them needing a
> filesystem, not a block device.  My option here would be to run NFS for
> shared storage, but this loses the ability to do snapshots (a must
> have).  LVM would work, but it's not able to be shared.

It is documented via the content types (only 'images' for ZFS over
iSCSI, but not 'rootdir'):


>From a quick glance, the only storage type that fits your needs, i.e.
snapshots, shared and support for 'rootdir' content type is Ceph/RBD.
Everything else requires workarounds and won't be fully integrated.

Best Regards,

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