How to back up a folder that's bigger than one disc

Choose the folder in the Backup Assistant of Burn by Zaweba and let it plan the discs. When a backup is bigger than one disc, Burn works out how many it needs, splits any very big files into numbered pieces, asks for each disc in turn and labels them Set 2 of 4 and so on. Every disc carries a restore index for the whole set.

Plain disc burning gives up when the files don't fit. A backup program has to handle the overflow for you, and that's what spanning does.

Picking a disc size that suits the job

A backup set includes the disc size, so the first choice is which blanks to use. Bigger discs mean fewer of them to burn, label and store, and fewer to swap during a restore. If a folder would take a dozen DVDs, it may be worth using Blu-ray if your drive writes it. Tools > Drive information shows what your drive can write.

You can also make a big backup smaller. A set can include every kind of file or only chosen kinds, and can leave kinds out, so you can skip things you don't need on disc. Hidden and system files are left out.

What happens during a spanned backup

Start the Backup Assistant from Home or with Ctrl+B, add the folder, set the options and give the set a name. Burn plans the discs before it starts. Files bigger than a disc's space are split into numbered pieces, so even one huge video file can be backed up across discs.

Burn then asks for the discs one at a time, with a message such as Insert disc 2 of 4. Each disc is burned and, with Check every disc after burning on, read back and checked file by file against the SHA-256 fingerprints taken before burning. A disc that fails can be burned again before you move on.

Every job shows its progress on the taskbar button and the tray icon, and a chime and notification tell you when it's done, so you can get on with something else between discs.

Keeping a set of discs in order

Numbering matters with a multi-disc backup. After the backup, Burn offers labels and covers with a label for each disc, marked Disc 2 of 3 and so on, made as an A4 PDF with crop marks for printing. If you'd rather write on the discs by hand, copy the set name and number from Burn's prompts.

Keep the whole set together. Because the restore index is on every disc, any one of them can tell Burn what the backup holds and which disc each file is on. When you restore, Burn asks for each disc it needs, joins the split pieces back into whole files and checks them all.

Making the next backup smaller

The set is saved as a chip on the home screen. Next time, open it and choose Only files changed since the last backup. Burn then writes only new and changed files, and its index points the unchanged ones back to the earlier discs. For a large folder that barely changes, that can mean one new disc instead of several.

The backup log records each run with its date, discs used, number of files and check result, and exports as CSV, which helps when the shelf of discs starts to grow.