Login freezes after entering pbuttword Obscurity, linux

We have seen this on some RHEL 4 DELL systems we have and it has been maddening to trouble shoot. You may be seeing something different, but our big symptoms when this occurs, is the failure to login, some application 'seem' to keep running for a while, no disk writes succeed, i.e. if you look invar-log for stuff that might normally be logged 1-min -- you can see that logging also stopped as the system started to fail.

If you were logged in on an xterm, you could give ps commands, but a file system access would lock up, and an 'init 6' would never complete. We did have the Magic sysreq key enabled, so we could, through keyboard shortcut, sync and unmount the disks in a somewhat controlled manner.

On one system we did isolate it and actually 'fixed' it. It was a name server, and we discovered that doing 'service named restart' -- was buttociated with the system becoming unstable. We started doing 'service named reload' -- and things have been good.

We worked with RedHat on this, and it looked like memory was getting fragmented, and that was the root cause of the problem. Still don't know why? Very strange.

Hope this helps.

-- John John Murtari Software Workshop Inc.