The choice of one compared to the other depends on the depth of encryption needed, the level of compatibility aimed, and the power of the Mac to complete the task Mac OS X manages by default 2 encoding schemes: AES-128 and AES-256. Cons: bigger than sparseimage when created. Pros: the modification of only one file affects only one band, and not the entire disk image, which turns backups more efficiently, even for a disk image sizing many GB. Sparse bundle disk image (Sparsebundle): this format is equivalent to Sparseimage, except that it is adapted to the local and networked incremental backups (like Time Machine or Personal Backup do), because, instead of creating a monolithic file of only one block, it gathers a package of bands.It always requires to define its size during its creation. Sparse disk image (Sparseimage): this format behaves like the standard Read/write, without its disadvantage: it grows bigger as it fills.It remains effective for cases where the size must be set from the beginning, in order to limit fragmentation, for example. Cons: its size is determined at the disk image creation (a 40MB disk image volume will take 40MB of real disk space). Read/write: the default format when continuing to work with files and to hide them from inquisitive eyes. ![]() This way to store files become useless: either you keep the disk image on your startup drive as a reference, or your archive it on a dedicated external medium. Once created, the resulting disk image is read-only (it cannot be modified any more). Compressed: the usual format to freeze a folder content taking up less possible space.There are many kind of disk images, but the most commonly used are the following ones, which refer to 4 different uses: It doesn't sound like it was reported as a bug, or opened as a case with AppleCare.Creating Disk Images as Substitute for SafesĪmong the tools provided by Apple with Mac OS X, the disk images are very similar to FileGuard safes. (Not a very good combination in several ways, but that's how it manages to avoid full backups of the encrypted sparse bundle.)Īnd I don't think the reference to a "guy at the Genius Bar" means anybody at Apple was really looking at anything to do with this. That's how Time Machine deals with a home folder that has File Vault enabled. A sparse bundle will be backed up band-by-band, not file-by-file. Unless I'm missing something, I don't think that applies here, or is likely to be changed. Would love to see some movement on this.here's the link to the thread: ![]() ![]() I tinkered with it this morning (on 10.6.4) and it's still a problem. At one point someone indicated that Apple Engineers were "working on the issue.", but nothing seemed to come from it. There is an archived thread that describes this in detail. It used to work in 10.5, but broke in 10.6.x. So I converted my encrypted sparse image to an encrypted sparse bundle, and now I can include it along with all my other files in my ordinary backups. Your backup software only has to copy the 8 MB band(s) containing any of that file's data (often only one). As a result, assuming your backup software treats the contents of bundles as individual files, you no longer have to back up a huge disk image just because a tiny file changed. What's cool about this is that if you change something on a sparse bundle (adding or modifying a file, for instance), only the band(s) containing that data change, not the whole bundle. (To verify this, you can Control-click or right-click a sparse bundle, choose Show Package Contents from the pop-up menu, and browse through its contents.) Inside that package is a folder full of bands - files that are each 8 MB in size, as many as are needed to hold the image's data. ![]() It's a bundle (also known as a package) - a folder that Mac OS X treats as a single file, which is also true of applications. What's different is that it isn't actually a single file, as all previous disk image formats were. :Ī sparse bundle looks and acts just like a sparse image - it can grow in size, can optionally be compressed or encrypted, and so on. Sparsebundle disk image instead of a sparseimage, that shouldn't happen. And since the image is large I run out of Each time I add/modify a file inside the image, then TM marks the whole image asĬhanged and hence backs it all up.
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