Accusys ExaSAN B08S2-PS - Manual (Page 74)

4. How to Use
User Guide Page 4-23
4.1.2.7.2 Cache
Figure 62: GUI “Cache”
Cache memory in the controller enhances read and write performance, improving overall storage
throughput streaming data can be queued into the cache to 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.