Tape (LTO-9 / LTFS)
Updated July 17, 2026
Tape (LTO-9 / LTFS)
Tape is the archival spine of a 3-2-1 setup, and a real air gap once the cartridge is on a shelf. This article explains how Hiberden's tape destination works, how cartridges are identified, and what actually ends up on the tape. The supported configuration is LTO-9 through an LTFS-capable drive.
LTFS: tape as a filesystem
Hiberden never talks to the drive over raw SCSI. It drives the vendor's LTFS tooling (the open Linear Tape File System) to mount the cartridge, then treats the mounted cartridge like any other filesystem: it writes files, reads them back, and verifies them. LTFS is what makes that possible, and it is also what keeps your tapes readable outside Hiberden.
Because the on-tape format is delegated entirely to LTFS, nothing in Hiberden is tied to a specific drive generation. LTO-9 is the configuration we claim, and we do not claim a tested generation matrix beyond it.
LTFS tooling on Windows
On Windows, the wired implementation is IBM's LTFS (Single Drive Edition). It is separate vendor software, not part of Hiberden, and it is only needed for a real tape drive: the built-in virtual tape drive is self-contained and needs no vendor software. Hiberden auto-detects IBM's LTFS in the standard install locations; if yours lives somewhere else, set a custom path in Settings > Tape.
A fresh LTFS install often leaves its Windows service stopped until a reboot. Hiberden detects that as its own distinct state and offers a one-click Start service. The app also distinguishes the other states you might hit: no drive on the bus, no cartridge loaded, a cartridge that needs formatting, and one that just needs mounting. If the drive is not showing up at all, see Tape drive not detected.
Adding a tape destination
Pick "Tape (LTO)" when adding a destination. There is no path to configure: archives are written to the connected tape drive. Save & test runs a real probe, checking that a drive is present and a cartridge can be mounted.
Cartridge identity: the volume label
Hiberden identifies a cartridge by its LTFS volume label. A blank, unlabeled cartridge is refused for writing, on purpose: if Hiberden wrote to an unlabeled cartridge, the segments on it could not be attributed back to that cartridge, and could not be found again on restore. Label the cartridge with mkltfs first, then Hiberden will accept it.
Spanning across cartridges
An archive too big for one cartridge is split across several. Hiberden prompts you to swap cartridges as each one fills, and every segment is read back and hash-verified as it is written. A span can start on a partially used cartridge: Hiberden fills the remaining space, keeping 64 MiB of headroom for the LTFS index, before prompting for the next cartridge.
Each cartridge in the set carries its own sidecar recording its segment's offset, length, and hash, plus the volume label and ordinal; a chain manifest describes the whole set. Restoring a spanned archive works the same way in reverse: cartridge by cartridge, with swap prompts and per-segment hash verification.
The catalog knows what is on which cartridge
You should not have to mount a tape to find out what is on it. The catalog tracks each cartridge's capacity, used space, and contents, so "what is on tape X" and "which cartridges do I need for this restore" are answered from the catalog with nothing in the drive.
One tape caveat worth knowing up front: per-file restore from tape is not supported, because tape is sequential media. Restore the whole archive from the tape copy, then take the files you need from the restored folder.
What actually lands on the tape
An archive on tape is an ordinary file on the LTFS volume: one standard TAR plus a JSON sidecar. Any LTFS-capable system can mount the cartridge and open the TAR with standard tools, no Hiberden required. The full layout, including spanned sets, is documented in On-tape format (LTFS and the JSON sidecar).
An honest note on testing
This build's tape workflow (write, span, verify, restore) is exercised end to end against Hiberden's built-in virtual tape drive, which presents the mounted cartridge as a real drive letter. We have not validated this build on physical tape hardware, and we will not claim otherwise. The virtual drive is also the easiest way to evaluate the whole tape workflow before buying a drive.