Spanning (old)
Last updated
Last updated
When a source doesn't fit the mounted tape, Canister will ask you if you want to span your data across multiple tapes.
You can use both preformatted tapes and non-formatted tapes. If a tape isn't formatted, Canister will prompt to format during the Spanning process.
When starting a Spanning transfer, you can add a Spanning Label to make it easy to find your spanned data later:
In turn, Canister will group your tapes in the Catalog:
How Canister's spanning technically works is described in depth on our blog:
As with all things LTO, stuff happens. Where with hard disks it's easy to redo something, due to LTO's linear nature, errors tend to be showstoppers - at least temporarily. When spanning the chance that a tape runs into an issue or that an archive fails for some reason, is of course compounded.
Canister gets around this problem by using its Dupe Detection implementation to the fullest: in case an error happens with any tape during a spanning archive, simply start over. Select the source, feed in the first tape, and start the archive. Canister will automatically understand tape 1 is full, and ask for the next. Rinse, repeat.
It's important to feed Canister all tapes that were finished properly, and then feed it the tape that had the error. If the tape still mounts, Canister will proceed as is. If not, Canister will offer to format the tape, and then you're back on track.
It's likely that you won't fill up the last tape in a spanning set. Therefore you can add anything you want to that last tape at a later time - no previously archived data will be affected.
If the to-be-archived files will fit on your last tape, Canister will just add it to the tape. If it doesn't, you'll be asked to add a Spanning Label. If this is new data that belongs to the whole spanned group of tapes, then it's useful to use the same label as before. This way, all newly added data gets grouped in Canister's Catalog.
When using a tape library instead of a desktop LTO drive, format all LTO tapes before starting with spanning data. Due to how libraries work with LTFS, Canister currently cannot offer mid-transfer formatting of new tapes.
Spanning while creating simultaneous archives is not supported.
