Grass Valley Network Attached Storage System Serial ATA Network User Guide v.1.0.04 - Manual (Page 142)

Configuring Controller
Digital News Production 141
Configuring Controller
To configure certain RAID controller features, from the Storage menu choose
RAID System | Controller | Configure Controllers . The Controller window
appears:
1. Click in the check box to enable read cache (or to disable it when it is
already enabled). If read cache is enabled, the controller checks cache
memory for the requested data. Only if the data is not in cache does it read
the drives. If read cache is disabled, data is always read from the drives. The
default is enabled.
2. Click in the check box to enable read ahead (or to disable it when it is
already enabled). Read Ahead improves data retrieval performance because
the controller always reads a full data stripe into cache. If the stripe size is
8KB and the read request is for 1KB, the controller reads 8KB. If subsequent
read requests are for sequential data, it will already be in cache. Time spent
reading the drive is minimized. The default is enabled.
3. Click in the check box to enable write cache (or to disable it when it is
already enabled). If write cache is enabled, the controller saves the data in
cache memory and returns a Command Complete before actually writing the
data to the drives. If write cache is disabled, the controller writes the data to
the drives before issuing a Command Complete. Enabling write cache
increases write performance, but introduces some data vulnerability. If data
integrity is the primary consideration, disable write cache. For a single
controller, the default is enabled. For a dual controller system, the default is
disabled.
4. Click in the check box to enable write cache mirroring (or to disable it when
it is already enabled). This feature is available only in a dual controller