Note: This is a "documenting my process" question that I'll be writing an answer to. Happily, serverfault already helped me solve this, because writing up my situation so others would be able to assess it caused me to realize what was happening.
- I'm using the ext3 filesystem on a Debian server.
- Despite very little activity happening on my main filesystem with respect to files, there's tremendous activity from
- This activity comes in periodic bursts that raise my overall average writes to about 2 MB/sec (which is of great concern to me because I'd like to get some SSDs and that rate is actually enough to seriously threaten the very generous write endurance of current models).
- I've already made the filesystem in question mount with
- I've already increased the filesystem's journal commit interval from 5 sec to 300 sec.
What is going on? (Spoilers: it was a userspace thing. I'm writing this mainly to highlight the possibly-counterintuitive underlying issues.)