On Wed, 2011-04-13 at 13:06 -0700, Florin Andrei wrote:
Running v5 64bit on a Dell 1950.
A cluster of 3 DB machines, identical hardware. One of them suddenly became slower 2 weeks ago.
tar -zxf with a large file on this machine takes 1.5 minutes, but takes only 10 seconds on any of its siblings. CPU usage seems high while untarring, with lots of user and sys cycles being used, but almost no wait cycles. It doesn't matter whether I untar on a local disk, or on a fiber channel SAN volume, it's slow anyway.
scp a file over the network is slow too: 6 MB/s to this machine, 70 MB/s to its siblings.
However, this is just as fast on all systems, including the "sick" one:
# time dd if=/dev/zero of=/dev/null bs=1M count=100000 100000+0 records in 100000+0 records out 104857600000 bytes (105 GB) copied, 2.59213 seconds, 40.5 GB/s
real 0m2.600s user 0m0.025s sys 0m2.550s
/proc/cpuinfo looks fine. Nothing suspect in dmesg.
Reboot doesn't fix it. Power off / power on doesn't fix it. Single mode is slow too, and I tried a couple different kernels.
Dell's online diagnostics program could find nothing wrong with it.
/var/log/messages was full of "ntpd[7313]: frequency error -1707 PPM exceeds tolerance 500 PPM" messages. There was a lot of messages about "the system limit for the maximum number of semaphore sets has been exceeded"; there was indeed a lot of leftover semaphores created by NRPE (owned by the nagios user); I deleted them but nothing has changed, so they were a symptom, not the cause.
Are the system times different between the siblings? Are all 3 siblings running ntpd and using the same time source (server(s))? Do the symptoms change with ntpd stopped/running? Are the frequency offsets the same on each sibling?
Since your log messages appear to be ntp related, you might try resetting your frequency offset and drift values. Having a -1707 PPM offset could cause many issues like you describe.
service ntpd stop ntptime -f 0 echo "0" > /var/lib/ntp/drift service ntpd start
I'm still kind of hoping it's a software issue, but chances are slim. OTOH, I can't imagine any hardware problem that would exhibit these symptoms.
Any idea what to test?