On occasion, you will see the advice that the ext3 file system is not suitable for Solid State Disks (SSD’s) due to the extra writes caused by journaling — and so Linux users using SSD’s should use ext2 instead. However, is this folk wisdom actually true? This weekend, I decided to measure exactly what the write overhead of journaling actually is in actual practice. For this experiment I used ext4, since I recently added a feature to track the amount of writes to the file system over its lifetime (to better gauge the wear and tear on an SSD).

In one of the comments to my last blog entry, an anonymous commenter writes: You seem to be taking a different perspective to linus on the “adapting to the the disk technology” front (Linus seems to against having to have the OS know about disk boundaries and having to do levelling itself) That’s an interesting question, and I figure it’s worth its own top-level entry, as opposed to a reply in the comment stream.

I recently purchased a new toy, an Intel X25-M SSD, and when I was setting it up initially, I decided I wanted to make sure the file system was aligned on an erase block boundary. This is a generally considered to be a Very Good Thing to do for most SSD’s available today, although there’s some question about how important this really is for Intel SSD’s — more on that in a moment.