Machine slows down during heavy I/O and retries on AS3up4

Hi All,

We are facing some problem with below environment.

Processor : Intel Itanium 2 (IA64)
OS : AS3 Update 4 (Errata kernels  2.4.21-27.0.2.EL)
Memory : 32 GB
Number of processor =3D 4
HBA Card:Qlogic. 4 HBA ports

Observations:
- Heavy I/O is going on 2/3 raw devices bind to SCSI devices.
- Path plug pull was done. (Fiber channel cable was plugged out.)
- Upper layer application retries I/O due to fiber channel pullout.

In above scenario the machine slow down was observed. Simple
command like `ls` was taking considerable time.

When we reduced memory from 32GB to 8GB behaviour was not
reproducible. Please let us know whether it is issue due to
high memory (32GB) usages.As per Redhat on ia64 processor on AS3up4 works
fine with 128GB memory.

Please let me know the probable causes of the above problem.Please inform
if anybody has faced the similar problem.Any information on this regard
will be highly appreciated.

Thanks in advance.

Regards
Sandhya Suman