User Manual

589
Product Manual Technology Background
write cAche POlicy
• WriteBack–Dataiswrittenrsttothecache,thentothelogicaldrive.Betterperformance.Vesshasa
cachebackupbatterytoprotectdatainthecachefromasuddenpowerfailure.
• AdaptiveWriteback–See“AdaptiveWritebackCache”below.
• WriteThru–Also“WriteThrough.”Dataiswrittentothecacheandthelogicaldriveatthesametime.
Safer.
If your write cache policy is set to Write Back, the write policy automatically changes to Write Thru when all
of the following conditions occur:
•
ThelogicaldrivewritepolicyissettoWriteBack
• TheAdaptiveWritebackCachefeatureisenabled
• Thecachebackupbatterygoesofine
When the battery comes back online, the write policy automatically changes back to Write Back.
Also see “Viewing Battery Information” on page 119.
Forced Read-Ahead Cache
On the Vess subsystem, you can set the logical drive read cache policy to Forced Read Ahead an enable the
aggressive pre-fetch feature.
The Forced Read-Ahead cache policy setting provides predictive pre-fetching of data requests, allowing the
controller to aggressively buffer large chunks of data in cache memory to prevent frame drops on high-bandwidth
video playback. Not normally enabled for non-video applications.