Windows Storage - Compression

You use compression to save on disk space, but the act of compression to store, then de-compression to read, uses CPU power. Its a trade off, you need to decide which is the most important, saving CPU cycles or saving disk storage. Generally, you would compress files which are not used much, and not compress very active files. Compression could reduce your disk usage by about 60%. Compression does not work well on files that are already compressed, for instance .jpg, .mp3 or .mpg files. Microsoft also does not recommend that you compress files bigger than 30MB as the files become fragmented and performance suffers.

So, compression saves some disk space but burns your CPU and does not work well for some files. Is compression worthwhile? In my opinion, no as it is cheap enough to add more disk space to a server. However if you have an old, historical text folder about that you rarely use, it could be worthwhile to compress it. An other useful reason to compress is if you are sending a few text files by e-mail.

On NTFS volumes, you can compress individual files, folders, or entire drives by simply right clicking on the object, selecting 'properties' then the 'advanced' tab. You should see a box like the one below. Just click on the 'Compress contents to save disk space' button. When you compress a whole folder, any new files added to that folder are automatically compressed as well.



How do you know if compression is active? Open any folder window; choose 'View', 'Options'; and on the View tab check the box labeled 'Display Compressed Files and Folders with Alternate Color'.

Older releases of Windows gave you the option to compress old files with the 'Disk Cleanup' utility, but that was removed in Windows 7, which probably indicates how useful Microsoft thinks compression is.

The other useful option is to be able to zip up a folder or a group of files to send by email. To do this, either select the files you want by clicking on them with your mouse while holding the ctl key down, or select an entire folder. Right click on them, then take the 'Send to' option then 'Compressed (zipped) folder'. This will create a new, zipped folder while leaving your original data intact.

Remote Differential Compression

If you are working with a very distributed infrastructure, maybe using Distributed File System, then you could end up transferring a lot of data around your network.
Remote Differential Compression (RDC) is intended to help manage this data transfer over limited-bandwidth networks. If a file is updated, RDC will only transfer the changed parts of files, called deltas, instead of the whole file. Microsoft claims that RDC can reduce bandwidth requirements by as much as 400:1.