Dell PERC 4/im - Manual (Page 3)

The user can configure the mirroring attributes during initial setup and reconfigure them in response to hardware
failures or changes in the environment using the BIOS Configuration Utility.
Integrated Mirroring Firmware
This section describes features of the Integrated Mirroring (IM) firmware.
Host Interface
The IM host interface uses the "Message Passing Interface". Through the Fusion-MPT interface, the host operating
system has access to the virtual IM drive as well as the physical drives. This allows support for domain validation and
Ultra320 SCSI expander configuration.
Initialization
The firmware enables the physical drives in the IM volume before becoming operational to the host OS. The I/Os
include the following:
Inquiry
Test Unit Ready
Start Stop Unit
Read Capacity
Inquiry/EVPD to read the serial number of the disk from the "Vital Product Data"
Mode Sense/Mode Select I/Os to configure disk write caching
Disk write caching may be enabled or disabled, depending upon the Configuration Utility settings. During initialization,
the firmware determines whether full or partial synchronization is needed. The firmware may also be reset without
rebooting the OS.
It may take the firmware from 5 to 30 seconds to spin up the IM physical drives before becoming operational to the
host. However, the SCSI BIOS does not have to spin up the IM physical drives, this should have little impact on
operating system boot time.
Hot Swap
The IM firmware supports "hot swap." The hot-swapped hard drive is automatically resynchronized in the background,
without any host or user intervention. The hot-swapped disk must be at the same physical SCSI ID as one of the
physical disks configured in the IM volume. The firmware detects "Hot Swap" removal on preconfigured IM drives
through a failed SCSI I/O with "Selection Timeout" status, and marks the disk with a status of "Disk Missing". If a
disk has a "Disk Missing" status, it is periodically polled with an Inquiry CDB to detect disk insertion.
Following a "hot swap" event, the firmware readies the new physical drive by spinning it up and verifying sufficient