User`s guide

Integrated Mirroring Overview 13
SCSI ID Assignment
A single logical drive is presented as the combination of a set of physical member disks. Each
individual member disk is hidden and returns a “selection timeout” when accessed. The SCSI
Target ID of the IM logical drive is assigned when the logical drive is created. The lowest SCSI ID
of the selected disks is used.
Disk Write Caching
Disk Write Caching is not supported and not configurable.
NVSRAM Usage
IM firmware utilitizes a 32 Kbyte NVSRAM in order to perform write journaling. This is not a user-
configurable setting. Write journaling is used to verify that the mirrored disks in the IM volume are
synchronized with each other. The NVSRAM also stores additional code and data used for error and
exception handling, and it stores IM configuration information during serial EEPROM updates.
The disk write log uses approximately 4 Kbytes of the NVSRAM.