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