First a brief history:
---------------------
The system is an AlphaServer 2100 4/200 with 192 Mb Ram, which was
upgraded from Digital Unix 2.0 to 4.0b in March 1997.
The machine's primary purpose in life is to be a news server, using Inn.
Around the same time as the OS upgrade, NNTP feeder software was
upgraded from nntplink to innfeed.
The news spools are on UFS file systems, split (fairly evenly) between
two SCSI controllers. Most everything else, (except / ) is on AdvFS.
The problem:
-----------
The system is not performing up to our expectations. Since the OS
upgrade in March, the cpu spends most of its time in system time. Idle
time is consistently near 0%. User time has increased, but not
dramatically. Essentially, we lost the cpu's idle time to system time
when the OS was upgraded.
Our attempts to track this down:
-------------------------------
We added an 8 Mb Prestoserve board, hoping to increase the performance
of the disk subsystem. Note that we only cache the news spools on the
Prestoserve board.
We switched the history database from AdvFS to UFS.
We altered our expiry runs from three times daily to twice daily during
times when there are the least number of reader connections.
None of these have appeared to give any significant improvement to our
system's performance.
Top shows that the cpu is normally >80% in system time, <10% in user
time, and the rest in nice ('nice top'). 0.0% idle, very consistently.
Occasionally system time will drop to >60% with user time picking up to
<=35%, but idle remains at 0.0%
We collect iostat and vmstat data regularly which indicates very much
the same as top shows.
What I'm hoping to find out:
---------------------------
Is there anyone else out there, using a similar system (past or present)
who has seen the same performance problems we are seeing? Does anyone
have any suggestions as to what I might do to try and get some of the
performance back on this system?
Thanks for your time.
----------------------------------------------------------------------
Sylvain Robitaille syl_at_alcor.concordia.ca
Assistant to the System Managers Concordia University
Computing Services Department Montreal, Quebec, Canada
----------------------------------------------------------------------
Received on Tue Jan 06 1998 - 00:20:43 NZDT