Testing EXT4 & Btrfs On A Serial ATA 3.0 SSD
Last month I wrote a review on the OCZ Vertex 3 240GB solid-state drive, which was a very impressive Serial ATA 3.0 SSD. The performance of this solid-state drive was terrific and a huge improvement over previous-generation SATA 2.0 SSDs and over SATA 3.0 hard drives. All of that testing was done when the drives were formatted to the common EXT4 file-system type, but in this article are more benchmarks from the OCZ Vertex 3 as it's tested with Btrfs and various mount options.
The OCZ Vertex 3 was benchmarked using the Linux 3.1 development kernel with the EXT4 file-system and its default mount options, with Btrfs using its default mount options, and then when applying several different mount options. The mount options tested on the SATA 3.0 solid-state drive were nossd, compress=zlib, compress=lzo, and space_cache.
The nossd option is to disable the SSD optimizations of the Btrfs file-system. Previously an SSD mount option had to be manually applied, but now Btrfs attempts to auto-detect if the file-system is residing on a solid-state medium. The Btrfs SSD mode has been around for over two years and early tests I did showed that it was of some benefit, but the nossd results show what the difference is at for the modern Btrfs in the Linux 3.1 kernel.
The compress=zlib and compress=lzo mount options are for enabling file-system-level data compression. The zlib mode has been the longest standing Btrfs compression mode that is the default. The LZO compression mode was added in the Linux 2.6.39 kernel and provides the fastest level of compression. Btrfs compression can be used to enhance disk performance and just earlier this year are some other benchmarks of Btrfs LZO compression.
Lastly, the space_cache option stores the free space disk data on-disk to make the caching of a block group much faster. This feature was added to the Btrfs file-system in the Linux 2.6.37 kernel. Last December I put out benchmarks of the Btrfs space cache option.
Now it is a test to see Btrfs and these mount options work for this blazing fast OCZ solid-state drive. Testing was done on a system with an Intel Core i5 2500K Sandy Bridge CPU and 4GB of RAM. An Ubuntu 11.10 development snapshot was the operating system with the latest Linux 3.1 development kernel at the time of testing.
All benchmarking was carried out by the Phoronix Test Suite.