Accusys ExaSAN A12S2-PS - Manual (Page 78)

4. How to Use
User Guide Page 4-27
dramatically accelerate read performance. Under different applications, cache has
different influence on the RAID system.
Controller Cache – Check this box to enable the controller cache. This speeds up the
data transfer to and from the disks.
Caution
If controller cache is enabled, it is suggested that you use a UPS
(uninterruptible power supply) system to prevent a data loss
scenario.
Synchronize Cache – Check this box to enable cache synchronization. When
Synchronize Cache mode is disabled, the RAID controller works correctly but does not
actually perform any cache flushing. For video capture, disable synchronization
because the video capture needs to be able to constantly write data to the RAID
storage without long SYNCHRONIZE_CACHE latency. Synchronize cache commands
the controller to regularly synchronize the information on the drive and is usually used in
conjunction with the UPS.
Note
This option is available if Mode > Equalization Mode is
unchecked.
Read Pre-fetch – Identifies sequential access patterns and aggressively pre-fetches
patters into cache. From the drop down list, choose the number of stripes to pre-fetch.
The default is 32; this is the recommended number.
Drive Cache – Choose which drives to cache. When more than one application
accesses the database, the first applications cache needs to synchronize with the
second. Each drive contains a built in write cache; checking these boxes chooses
which drives to enable the caching on. Caching improves the efficiency and speed of
data transfer.
All Drives Cache On/All Drives Cache Off – Click this button to enable/disable the
caching on for all available drives.
4.1.2.7.3 MISC