Gateway E-842R, User Manual

Page: 150 / 164

APPENDIX C: Statistics www.gateway.com
144
Command cluster statistics
To increase performance, the controller can cluster sequential write commands
together to create a larger write command. This results in less commands being
sent to the disk drives. Additionally, if sufficient data is clustered by the
controller, it can perform a full stripe write for RAID 5/50 arrays. This significantly
improves performance. In cases where the host does not send a sufficient
number of outstanding writes, writeback cache can be used to delay the write
to disk, increasing the likelihood of clustering more data.
Read-Ahead Command Hit Rate This is the percentage of read command hits versus the
total number of read commands that have been issued.
This gives an indication of the sequential nature of the
data access pattern from the host.
Read-Ahead Command Efficiency This is the percentage of the number of read command
hits versus the projected number of read-ahead
command hits. This is a measure of the efficiency of the
read-ahead algorithm. A low value means that much of
the data that the controller reads in the read-ahead
command is not actually requested by the host.
Statistic Description