I help to support a system (similar to mine) with a 3ware 9750-24i4e and
when you rm -rf a directory with too many files, the system will act
lagged, lock up for periods of time and drop connections (including samba
shares) to and from the host. Its so bad it cannot even talk to the UPS
for example (ups: communications lost, e.g. from nut). This is pretty bad
and I've remounted my XFS FS w/out delaylog but for the xfstests package,
it really needs to test with a few million files in a directory or two,
and you should easily be able to reproduce the problem.
When the delaylog option is removed, the files are removed slowly, but
there are no errors, SSH/samba connections do NOT drop, etc, please look
into this, thanks.