HP-UX 11i v3 Mass Storage I/O Performance Improvements

The cell-local round robin scheduling policy is beneficial in those cell based system configurations
where cell local memory is set up and a uniform distribution of interface cards across all the cells of
the system exists.
Boot and scan improvements
The HP-UX 11i v3 mass storage stack fully parallelizes the probing of HBAs, targets, and LUNs to
reduce I/O scan and system boot times. LUN opens and closes are also parallelized to further reduce
scan and boot times and other operations that are open/close intensive. The mass storage stack also
enables asynchronous detection of SAN configuration changes and dynamic rescanning of the SAN
along with automatic creation of new device files to more quickly enable new hardware.
HP tested an rx8620 server with 8 processor cores and 2.8 GB memory, with two 2 Gb/s A6795A
and six 4 Gb/s AB379B Fibre Channel adapter ports each connected to 600 LUNs in an XP disk
array. The 8 FC HBA ports were connected through a switch to 4 target ports on the XP array, for a
total of 8x4=32 paths per LUN, and a total of 600x32=19,200 LUN paths on the system. Figure 5
and Figure 6 display the results of the testing and show significant improvements in scan and boot
times on HP-UX 11i v3.
The shutdown and reboot time in Figure 5 is the total time from initiating the reboot (by invoking the
reboot command) until the system is booted back up to the console login. The use of the new –N
option to ioscan, ioscan –kfnN, is included in the table for comparison with the legacy ioscan
–kfn command option. The ioscan –kfnN takes less time because the –N output results in fewer
DSFs to display: 600 DSFs (corresponding to the 600 LUNs on the system) versus 19,200 legacy
DSFs (corresponding to the 19,200 lunpaths). For information the 11i v3 device file formats, see the
HP-UX 11i v3 Mass Storage Device Naming white paper.
7