Hello,
Ive got a funny problem with ADVfs. Sometimes it takes 30 seconds or
more to delete a 20 kbyte file.
I have a news spool on an ADVfs filedomain. The news spool is 3 gbytes
in size, and used the defaults during the creation of the file domain
and fileset. The file domain is shared by other filesets. The disk size
is 9 gbytes, and the file domain shows a fragmentation aggregate i/o
throughput of 91%.
The system is OSF/1 3.2a on a 3000/400 with 96 mbytes of memory. The
only processes active are the rm command, and monitor/top. (INN is dead).
I am deleting the entire news spool, retaining the directory structure
with a command along the lines of
find /news/spool -print | xargs -l48 rm
which seems to be the most efficient way of doing it.
Also the script;
foreach file (/news/spool/rec/cooking/*)
echo $file
rm $file
sleep 1
end
Is a handy way of watching this problem.
All the files are small, with an average of 20-30kbytes.
What happens is that the rm command will delete files very sporadically.
Some files get deleted quickly (ie normally) others take 30 seconds
or more to delete. There seems to be no pattern to the 'problem files'
but one in 10 files seems affected on average. The disk (elite-9) seems
capable of sustaining 1500 kbps in normal operation looking at monitor,
but during these freezes the drive light goes on permanently, and the
transfer rate drops to a few hundred kbps, with a tps of 50 or so.
Also every other access to this disk freezes too. 'ls' commands,
nfs, - everything.
The symptoms seem the same as trying to delete a Large (several 100
mbyte), badly fragmented file on a ufs partition. ie. disk thrashing.
In 10 hours the find command above has managed to delete 40 mbytes
of files. The find and rm commands mostly are in the WAIT state.
Questions:
Anyone else seen this?
Is there anything else I can check/tune?
(cpu is idle, no other disk accesses, plenty of memory used by UBC.)
Is there a Fix?
I remember that ADVfs had a problem with lots of small files a while ago
(vn 2.0 OSF/1). Is this still the case? Should I be using a suitably
tuned ufs for this?
- Also, Is there any real information on tuning ADVfs? Or is it a case
of 'no user serviceable parts'?
Thanks,
Andy.
--
atp_at_mssly1.mssl.ucl.ac.uk Andy Phillips
atp_at_mssl.ucl.ac.uk Mullard Space Science Laboratory,
phillips_at_isass1.solar.isas.ac.jp Dept. Space and Climate Physics,
mssly1::atp University College London.
Received on Sat Jul 29 1995 - 14:36:31 NZST