Compressing a CentOS 6.5 root image file

Let start our analysis compressing a mostly executables-rich dataset: a minimal CentOS 6.5 root image. Executables and binary files can often be reduced – albeit with somewhat low compression ratios.

As you can see, both lz4 and lzop maintain their promise to be very fast, both at compression and decompression – albeit lz4 is the absolute winner. On the other hand, they have relatively low compression factor. However, ask them to increase their compression ratio (via “-9” switch) and they slow down immensely, without producing appreciably smaller files.

Gzip and especially bzip2 shows are not so good – while their compression factor is better (3X), they suffer a massive performance hit.

7-zip and xz have very low compression speed, but very high compression ratio and acceptable decompression speed.

Remember that these are single-threaded results. Moder CPU, with multiple cores, can be put to good use using some multi-threaded compression programs:


Pigz, pbzip2 and pxz all produce way better results than theri single-threaded counterparts. However, while compression scaling is often very good, only pbzip2 is capable of decompression acceleration also.