SquashFS: Not Just for Embedded Systems
Jun 10, 2009, 22:32 (0 Talkback[s])
(Other stories by Jeffrey B. Layton)
"The original file was 3.2MB and after using gzip, with the "-9
option that provides maximum compression, the file is 268KB. Also
notice the the extension ".gz" to indicate that the file has been
compressed with gzip. The compression ratio, which is the ratio of
the original size to the compressed size, is 11.9:1. The
compression ratio is very dependent on the uncompressed data (how
compressible is the data?) and the compression algorithm.
"There are generally two types of algorithms - lossless and
lossy. Since this article is about data it will focus on lossless
algorithms that have an encoding that be reversed to recreate the
data exactly. There are a huge number of compression algorithms
that take data and find a new encoding of the data that is much
smaller. The difference between algorithms focuses on the
techniques that create the new encoding. From the user perspective
two of the biggest concerns are how much compression can be
obtained and how much time and/or CPU usage it takes to perform the
compression (or uncompression). However, the goal of all of them
remains the same, to reduce the size of data to save space.
"The primary trade-offs in compressed file systems is that it
takes CPU cycles and time to compress and uncompress data in return
for reduced storage space. If you have the cycles and don't need a
fast file system then you can save space. Alternatively, if you are
severely memory or storage space constrained, then compressed file
systems may be the only choice. This is most common in embedded
systems that have severe storage restrictions."
Complete
Story
Related Stories:
- NILFS: A File System to Make SSDs Scream(Jun 03, 2009)
- Now ready for testing, Tiny Core V2.0 Release Candidate 4(Jun 01, 2009)
- FS_scan: Getting Detailed with Your Data(May 27, 2009)
- Btrfs Is Not Yet The Performance King(Apr 30, 2009)
- Linux Don't Need No Stinkin' ZFS: BTRFS Intro & Benchmarks(Apr 22, 2009)
- That massive filesystem thread(Apr 16, 2009)
- Btrfs, Squashfs, and Tuz, oh my!(Mar 26, 2009)
- Btrfs and Squashfs merged into Linux kernel(Jan 12, 2009)
- Squashfs Aiming For Mainline Kernel(Nov 08, 2007)
