Read Before Installing Updating HP-UX 11i v2, September 2004

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System Hangs After Issuing Large I/O (>512 KB in
size) to Fibre Channel Devices
System hangs may be experienced after issuing large I/O (>512
KB in size) directly to physical disks accessed by a single port
Fibre Channel adapter (product number A6795A or A5158A,
claimed by the td driver).
I/O through file systems and/or logical volumes will not issue
such a large I/O. But LVM operations, for example, lvextend
and lvremove, performed on a volume group with a large
number of disks may issue large I/O for updating LVM metadata
on the physical disks. A fix will be provided at a later date.
What To Do
A workaround is available which basically limits the maximum
I/O to a Fibre Channel device to 512 KB. But some performance
degradation may result from this workaround. Contact HP
Support to discuss the problem.