Asus LSI SAS3442X-R - Manual (Page 22)

2-6 Overview of Integrated Mirroring and Integrated Mirroring Enhanced
Version 1.1 Copyright © 2006, 2007 by LSI Logic Corporation. All rights reserved.
order to verify the configuration. The usable disk space for each member
disk is adjusted down when the configuration is created, in order to leave
room for this data.
2.4.3 Hot Swapping
The 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 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 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.
2.4.4 SMART Support
SMART is a technology that monitors hard disk drives for signs of future
disk failure and generates an alert if such signs are detected. The
firmware polls each physical disk in the volume at regular intervals. If the
firmware detects a SMART ASC/ASCQ code on a physical disk in the
IM/IME volume, it processes the SMART data and stores it in nonvolatile
memory. The IM/IME volume does not support SMART directly, since it
is just a logical representation of the physical disks in the volume.
2.4.5 Hot Spare Disk
One or two disk drives per controller can be configured as global hot
spare disks, to protect data on the IM/IME volumes configured on the
controller. If the firmware fails one of the mirrored disks, it automatically
replaces the failed disk with a hot spare disk and then resynchronizes
the mirrored data. The firmware is automatically notified when the failed
disk has been replaced, and it then designates the failed disk as the new
hot spare.