2128 Views 6 Replies Latest reply: Jun 13, 2007 4:25 PM by Calvados
You can compress individual files or folders by selecting the item and pressing CTRL-mouse click to open the contextual menu. Select "Create Archive ..." from the contextual menu. You will need a de-archiver to extract the files from the archive. Try the freeware The Unarchiver - VersionTracker or MacUpdate.
OS X does not support compressed disks or files similar to Windows' filesystem.
Yes, older Macs did but not as part of the OS. Doublespace and Stacker were third-party add-ons. Such products do not exist for OS X to my knowledge.
You can create disk images using Disk Utility that support compressing data as they are added to the image file. You don't have to burn the disk image to a CD or DVD but can simply leave it on the hard drive and mount it when needed. You can specifically create a sparse image that starts off as a small image and will grow automatically as needed. Open Disk Utility and select Disk Utility Help from the Help menu to learn more about creating and using disk images.
I would caution against relying on compression too much. It is better to get a larger drive, or burn to CD and DVD than try to compress so much that data gets corrupted more easily. Secondly, compression software may not always be available in the future. So if there is a critical file you need, it is better to keep it in its native format. And of course always keep at least two copies of your data at all times.
I dunno, I think compression is pretty much a requirement for contemporary archive. One could even argue that storing files in a contemporary format is superior to just letting them sit on the filesystem.
For example, nearly all compressed files store some kind of CRC or digest of the data, so you at least know when your file becomes corrupt. Some include error correcting information and duplicates of the directory structure stored in a linear format, so that if the master directory goes down it can still manually scan through and find things that are still present. In addition, storing things in a compressed archive means that you're storing over fewer sectors, meaning that you have a lower probability of a bad sector appearing underneath your data. (though it will do greater damage to that file if it does)
This is part of my process of keeping two copies of my data at all times. In this case, I archive my images to flickr as well as burn them off to DVDs. However, it's nice to have them all instantly accessable, but nice to not have them take up more space than they need. When dealing with Tiffs (even compressed), this can be a very substantial savings.
Backup media have gone obsolete on me a lot more often than compression software. I now have no way to read most of the tapes and disks that I once used for backups, but I can still uncompress compressed files and archives that I compressed more than 20 years ago.
I agree that generally disk space is cheap, that compression can slow down processing, and that with compression corruption can cause more damage than otherwise. Backups will help protect against the risk of corruption.