Help;

Runnig AIX 4.3.2. F50

I'm receiving the following message.

"A problem was detected on ........date.

The service request number(s)/ probable cause or cause(s):

721-128: Error log analysis indicated a harware failure. 100% hdisk0

20-58-00-8,0 other SCSI Disk / Drive phyloc-code: NA."

I realize that DIAGELA (Diagnostic Error Log Analysys) is doing it's
job.
It reads the error log every morning about 3 am and shoots a note to
root if
it finds a new entry. DIAGELA appears to be trying to tell me hdisk0
(hard drive 0) has failed. But when checked hdisk0 appears to be
functioning fine.

Not long ago /tmp needed expanding but afterwards over 2gb of free
space remained.

Also, where is the error log DIAGELA reads located?

Thanks