Re: high load, no bottleneck

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

> We want fsync to do a disk sync, and client are unlikely to be fixable.
In my case, the culprit was SQLite used by browsers and dropbox.
As these were not fixable, I ended up writing a system that re-directs these
SQLite files to local storage (http://www.math.uni-bonn.de/people/ef/dotcache).

> RMW?
Read-Modify-Write.
On a RAID 4/5, writing anything that's not an entire stripe needs either to
read the rest of the stripe (to be able to compute the new parity) before 
writing the modified part and the parity; or it (if you modify less than half 
the stripe) reads both the old data and old parity to compute the new parity.
You don't have that on RAID 1, of course.