Chapter 3 System PreparationHPSS Installation Guide September 2002 157Release 4.5, Revision 2where logicalVolume is a raw logical volume that is sized to provide at least 20 seconds ofI/O throughput.To measure write performance on a single disk (see warning below):% iocheck -w -t 20 -b 1mb -o 1mb /dev/rwhere logicalVolume is a raw logical volume that is sized to provide at least 20 seconds ofI/O throughput.WARNING: The contents of this logical volume will be overwritten so be sure to use the correctlogical volume name.3.6.2 LinuxFor Linux, verify that there is a raw device mapping for each block device to be accessed by HPSS.To list all current device mappings:% raw -a -q/dev/raw/raw1: bound to major 8, minor 1/dev/raw/raw2: bound to major 8, minor 2Block devices can be mapped to raw devices at boot time by adding mapping information to the/etc/sysconfig/rawdevices file. To map the first partition of SCSI disk a to raw device raw1 and thesecond partition of SCSI disk b to raw device raw2, add the following lines:/dev/raw/raw1 /dev/sda1/dev/raw/raw2 /dev/sdb2On each Disk Mover node, measure the raw disk read and write I/O performance of all HPSS disksand verify that they are at expected levels.To measure read performance on a single disk:% iocheck -r -t 20 -b 1mb /dev/raw/rawXWhere X is the number of the raw device that is sized to provide at least 20 seconds of I/Othroughput.To measure write performance on a single disk (see warning below):% iocheck -w -t 20 -b 1mb -o 1mb /dev/raw/rawXWhere X is the number of the raw device that is sized to provide at least 20 seconds of I/Othroughput.WARNING: The contents of this disk will be overwritten so be sure to use the correct disk name.
