Is there a way to convert an existing storage volume attached to a container to a dependent volume attached to the same container? Without having to copy to a newly created volume, etc.
Unless I’m missing something, the online docs only mention dependent storage volumes briefly in the API docs but not in the main storage info (as at 24 Oct 2026)
Dependent volumes only arrived with Incus 6.23 (March 2026), and the feature is currently described in the 6.23 announcement and the API notes rather than the main storage guide. Reading the current Incus source, “dependent” is validated as a normal configuration key on custom volumes with no create-only restriction - unlike block.filesystem, which is explicitly guarded against later changes - so
incus storage volume set POOLNAME VOLUMENAME dependent=true
should be accepted on an existing volume. That is my reading of the source rather than something I have run, so treat it as a hypothesis. Two things before trying it: test it only on a throwaway volume and instance with a backup of anything you care about, because per the 6.23 announcement deleting the instance afterwards also deletes the dependent volume and its data; and the announcement example also sets dependent=true on the disk device when attaching, so you likely want both the volume key and the device flag. On a server older than 6.23 the key will not exist at all.
An important warning to add to my post above, because the lifecycle tie is destructive by design: per the 6.23 announcement, deleting the instance afterwards also deletes the dependent volume and everything on it, and instance snapshots, backups and migrations will include it from then on. So do not flip the flag on a volume holding data you cannot afford to lose without a backup, and if you try my suggestion, test it on a throwaway volume and instance, not on production data. On the documentation point, to be precise: the feature is currently described in the 6.23 announcement and the API notes, while the main storage guide does not cover it yet.