Integrated Mirroring Firmware - MSI MS-9282 User Manual

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.
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.
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 at-
tempted 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.
2.4.3 M etadata Support
The firmware supports metadata, which describes the IM/IME logical drive con-
figuration stored on each member disk. W hen 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.
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.
2.4.5 SM ART 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 sup-
port SMART directly, since it is just a logical representation of the physical disks
in the volume.
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
LSI SAS RAID
B-7