Problem/Justification
In TrueNAS Scale 25.04, there is no way to import vdisk with a sector size of 4096 bytes that were created with a previous version of TrueNAS Scale or TrueNAS Core.
On TrueNAS Scale 25.04, the virtual machines are managed with Incus 6.0.3 instead of libvirt but Incus (actually) supports only vdisks with a sector size of 512 bytes.
Impact
- TrueNAS users cannot easily recreate their VMs if they can at least import their previous zvols.
- Copying data between vdisks with different sectors size is sometimes impossible (see User Story below)
- Today, the only workaround would using iSCSI instead of vdisk. I have not tested yet but it may work because you can specify the sector size of iSCSI LUN. Nevertheless, it is really more complicated setup that may work only for data disks and not for boot disks.
Unlike other enterprise storage vendors like Dell, Netapp, etc., TrueNAS is the only storage platform that can run virtual machines. This huge competition advantage make possible to create all-in-one backup appliances for any application (Veeam, Proxmox Backup Server, etc.). It’s a pretty annoying to break these devices by removing support for virtual disks with 4096-byte sectors.
User Story
I run Veeam on TrueNAS. (I guess that it is a very popular use case). In my case:
- I run a Veeam Repository with XFS Fast Clone
- I have a 100TB zvol (with 4096-byte sector size)
- Thanks to Veeam deduplication based on XFS Fast Clone, this vdisk holds 230 TB of multi-year backup archives that takes physically only 60 TB.
- Recreating the data will take years because of the multi-year retention policy I need.