Performance Considerations - HP e3000 MPE/iX Manual

Special Considerations
In order to remedy this, you must change the system primary path from 8 to 15.
Please refer to the "System Startup, Configuration, and Shutdown Reference
Manual" for information on changing the system primary path. After the system
primary path is changed to 15.0.0, the system can find Ldev 1 and boot.
In the previous example, there was only one Ldev on the broken system primary
NOTE
path. If there had been other Ldevs on path 8, then in order to ensure that all the
volumes mounted, the actions described in "Rebooting With a Failed Primary
Path" would also have to be taken.
It is recommended that the user creates and maintains an alternate configuration
group that has the alternate paths for the system volume Ldevs configured to be
their primary path. That is in the io> section of SYSGEN and NOT in the ha>
section. In the case where the system volume set's path goes bad and you need to
reboot, you can use this alternate configuration group to ensure that the system
volume set mounts properly. (This assumes that all the system volumes are on
the same path. If they are not, then you may want to create multiple alternate
configuration groups, one for each path that contains system volumes.)

Performance Considerations

It is recommended that the user understand the performance characteristics of
the current system before making any non-HAFO configuration changes (i.e.,
changes in the io> section of SYSGEN) to accommodate HAFO. These changes
may need to be carefully planned in order to maintain system performance.
Also be aware that a HAFO event can greatly increase the I/O load on a given
path and can cause significant performance degradation. Actual performance is
dependent on the capabilities of a host device adapter card and the load. We
normally recommend no more then eight Ldevs on a host device adapter card for
"best" performance. If the load on the host device adapter card is relatively low
then the difference between eight Ldevs and fourteen Ldevs will not affect
performance. If the load on a host device adapter is "high" then when other
Ldevs have failed over to this host device adapter, performance degradation will
most likely occur.
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