I've got an odd situation that I need some advise on. I have two
computers that I am planning to use as a cluster. I initially started
with some left over Compaq Presairos with 667MHz CPUs. I loaded CentOS
4.3 and later updated to 4.4. Things ran normally, albeit slowly. I
had an opportunity to upgrade to a pair of IBM Netvistas with 2.26 GHz
CPUs, I did this by transferring the 160GB Western Digital IDE disks and
NICs but did not re-install the OS, just migrated the disks. Since then
they have had the following symptoms:
-Systems frequently boot faster than the disks can be spun up and have
to be soft booted to recognize and boot from the disks.
-Systems will bog down critically after approximately 24 hours loosing
system time at an increasing rate, ofrr instance a for loop that runs
date, hwclock ans then sleeps for 10 minutes will show time in sync for
the first few hours then the system time will begin to fall behind at an
increasing rate, after 24 hours the system time essentially stops
elapsing. It almost feels like the box has trouble processing
interrupts. Once it gets to this state performance becomes very
sluggish, for instance top will take up to 90 seconds to display it's
first screen and will not update on it's own, only when Enter is
depressed. At times top will show 0's across the utilization line for
everything including idle. I have gone as far as to boot one of the
boxes into single user mode and run the date/hwclock loop and even in
that state the system will bog down and gradually stop elapsing time
after 18-24 hours. Even shutting down is impacted. A reboot will take
well over an hour to process.
I had a copy of Ubuntu on my desk and have booted into that distro from
cd and it passes the date/hwclock test (actually lost 2 seconds over a
24 hour period but I can live with that via ntp). I'm downloading a
copy of the CentOS live 4.4 cd and will try this with that as well but
at this time does anyone see that this could be something other than a
disk incompatibility with the newer systems? Should I try
re-installing? If it is the disks, any thoughts on something I could
try to avoid buying new disks (I have tried setting the BIOS to both the
high performance and legacy disk modes (not entirely sure what's behind
that IBMism)).
Regards,
Chuck
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