Recovering a Virtualized TrueNAS Storage-Capacity Incident

A Proxmox host storage target reached 100% usage while also holding a large virtual disk presented to TrueNAS. The TrueNAS and ZFS layer could still report logical free capacity even though the underlying host filesystem had no room left.

This supports routine and contained TrueNAS and virtualized-storage troubleshooting. It is not a claim of catastrophic pool recovery, forensic recovery, or guaranteed recovery of irreplaceable data.

The recovery needed to preserve the virtual disk while distinguishing host XFS exhaustion from guest ZFS logical capacity.

• Mapped the affected VM storage through the Proxmox storage layer to the underlying host filesystem.\n- Distinguished host XFS exhaustion from guest ZFS logical capacity.\n- Preserved the TrueNAS virtual disk while reducing pressure on the exhausted host datastore.\n- Recovered host filesystem capacity, reattached the preserved virtual disk, and returned the TrueNAS pool through the correct import path.\n- Verified pool health and added operating guardrails such as capacity, quota, and autotrim planning.

Recovered capacity at the host layer, preserved and reattached the virtual disk, then brought the guest pool back through its proper import path.

The investigation treated the host filesystem, virtual disk format, virtualized NAS, and pool state as separate but connected layers.

Data-preserving sequencing kept the virtual disk intact while host capacity was recovered and the guest pool was returned through the appropriate import path.

The virtual disk was preserved, the TrueNAS storage returned online, and the host recovered substantial usable capacity.

Verification included the recovered host capacity, preserved and reattached virtual disk, and pool health after the correct import path.

This demonstrates layered troubleshooting, Proxmox storage mapping, XFS capacity diagnosis, qcow2 lifecycle handling, TrueNAS and ZFS administration, and data-preserving recovery sequencing.