![]() You can create a sparse bundle using Disk Utility in Mac OS X, as shown below. The size of the bands is determined by the size of the total image, and might be 1, 2, 4, or 8 MB. Then it will grow as you write to it, creating new few-MB files one after another to handle your data. ![]() So it’s very efficient to keep sparse bundles images in sync between media using a command like rsync.Ĭreate a 1 TB sparse bundle disk image and it will take up only a few megabytes of physical space until you add some data to it. And they consist of many (many!) “bands” of data, each stored in a separate file. Sparse bundles are thin provisioned, meaning they grow as you add data. Happily, Mac OS X supports a “sparse bundle” disk image that solves these issues. And the entire image is treated as a single huge file, so it’s not efficient to update a copy of it after you’ve changed something. When you create a disk image, you must specify the size of the virtual disk drive, and this space is typically consumed immediately regardless of how much data you actually write to it. So a 1 TB disk image will take up 1 TB of actual capacity on whatever drive you write it to. Sure, you could encrypt your whole drive but this isn’t always desirable for removable media (portable hard disk drives and thumb drives) since you often want to have some “wide open” space, too. Create a disk image with encryption and you can move it around from drive to drive or machine to machine without having to worry that someone else will get their hands on the content. ![]() My favorite use of disk images is as a secure, encrypted drive for important data. It could be a virtual hard drive for a virtual machine, a copy of a DVD or Blu-Ray disc, or an archive for an application that wants to use an entire disk. A disk image is a file on a disk that acts like a separate disk. Buy a 4 TB hard disk drive and you can format it and store (about) 4 TB of stuff on it.ĭisk images are a little less familiar to average folks, but they work pretty much the same way. We’re all used to dealing with hard disk drives and thumb drives: They offer raw “block” storage that is formatted with a file system and used by the operating system, applications, and us users. I suppose I should start with a bit of background info on why I love sparse bundles so much. So I thought I’d write up a bit on what they are and how they can be used. I’m a big fan of “sparse bundle” disk images in Mac OS X. They allow me to create encrypted repositories for valuable data that can efficiently be rsync-ed between disks and don’t waste a lot of space.
0 Comments
Leave a Reply. |