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I use a sparse bundle disk image, i.e. a disk image with variable size and consisting of multiple files under the hood, because it is more efficient to back up
by tqkxzugoaupvwqr 9y ago
I use a sparse bundle disk image, i.e. a disk image with variable size and consisting of multiple files under the hood, because it is more efficient to back up over a network. Instead of uploading a 50 GB file to a cloud storage on every backup, only a fraction of data has to be uploaded (the sparse bundle’s changed files) which makes backing up the 50 GB file very fast if only a few megabytes were added.
If anyone is curious: I use restic[1] as backup client and Backblaze B2[2] as backup storage. Works well with sparse bundles.
[1] https://restic.net https://restic.net
[2] https://www.backblaze.com/b2/cloud-storage.html https://www.backblaze.com/b2/cloud-storage.html
- woodfall 9y agoWait, why would the 50 GB need to be transferred fully every time if it was a fixed size image?
- tqkxzugoaupvwqr 9y agoThe very first backup of a fixed size image will be the full size of the image, e.g. 50 GB, no matter which backup software you use. Even if inside the image no files exist. The very first backup of a sparse bundle disk image will be ~100 MB (the initial size of that image). On repeated backups, some backup softwares operate on file level and upload the whole file if it changed. So if you have a fixed size 50 GB image, mount it, add a file, unmount it, it changed, and the whole 50 GB image file has to be uploaded (with some backup softwares).
- Nullabillity 9y agoSure, but any halfway competent backup program would split it into chunks before deduplication anyway, rendering the exercise pointless.