User`s guide

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5.2.2.4 Integrated Mirroring Firmware
This section describes features of the LSI Logic Integrated Mirroring (IM) firmware, which supports up to
two IM volumes per LSI Logic SAS controller.
5.2.2.4.1 Host Interface
The IM host interface uses the Message Passing Interface, as described in the Fusion-MPT Message
Passing Interface Specification. Through the Fusion-MPT interface, the host OS has access to the IM
volume as well as the physical disks.
5.2.2.4.2 Resynchronization with Concurrent Host I/O Operation
The IM firmware allows Host I/Os to continue on the IM/IME volume while the volume is being re-
synchronized in the background. Resynchronization is attempted after a hot spare is activated due to a
physical device failure, or after a hot swap has occurred to a physical disk in the IM or IME volume.
5.2.2.4.3 Metadata Support
The firmware supports metadata, which describes the IM/IME logical drive configuration stored on each
member disk. When the firmware is initialized, each member disk is queried to read the stored metadata in
order to verify the configuration. The usable disk space for each member disk is adjusted down to leave
room for this data.
5.2.2.4.4 Hot Swapping
The IM firmware supports hot swapping. The hot-swapped disk is automatically resynchronized in the
background, without any host or user intervention. The firmware detects hot swap removal and disk
insertion.
Following a hot swap event, the firmware readies the new physical disk by spinning it up and verifying that
it has enough capacity for the mirrored volume. The IM firmware resynchronizes all hot-swapped disks that
have been removed, even if the same disk is re-inserted. In a two-disk mirrored volume, the IM firmware
marks the hot-swapped disk as the secondary disk and marks the other mirrored disk as the primary disk.
The firmware resynchronizes all data from the primary disk onto the new secondary disk.
5.2.2.4.5 SMART Support
The IM firmware enables Mode 6 SMART on the member disks in the mirrored volume. Mode 6 SMART
requires each physical disk to be polled at regular intervals. If a SMART ASC/ASCQ code is detected on a
physical disk in the volume, the firmware processes the SMART data, and the last received SMART
ASC/ASCQ is stored in non-volatile memory. The IM/IME volume does not support SMART directly, since it
is just a logical representation of the physical disks in the volume.
5.2.2.4.6 Hot Spare Disk
One disk can be configured as a global hot spare disk, which protects data on the one or two volumes
configured on the controller. If the IM firmware fails one of the mirrored disks, the firmware automatically
replaces it with the hot spare disk. The IM firmware then resynchronizes the mirrored data. The IM
firmware is automatically notified when the failed disk has been replaced, and the firmware then
designates that disk as the new hot spare.