7-3
Chapter 7: Integrated Mirroring and Integrated Mirroring Enhanced
The advantage of an IM/IME volume is that there is always a second, mirrored copy of
the data. The disadvantage is that writes take longer because data must be written
twice. On the other hand, performance is actually improved during reads.
Figure7-2 shows the logical view and physical view of an IM volume.
An IME volume can be configured with up to ten mirrored disks. (One or two global hot
spares can be added also.) Figure7-3 shows the logical view and physical view of an
Integrated Mirroring Enhanced (IME) volume with three mirrored disks. Each mirrored
stripe is written to a disk and mirrored to an adjacent disk. This type of configuration is
also called RAID 1E.
Figure 7-1. Typical Integrated Mirroring Implementation
Figure 7-2. Integrated Mirroring Volume
IM Volume
Primary Mirror
LSI Fusion-M PT
Controller
NVSRAM
(For Write
Journaling)
Flash
(For Configuration)
Memory Bus
SAS
LBA N
...
LBA N
LBA 3
LBA 2
LBA 1
...
LBA 3
LBA 2
LBA 1
LBA N
...
LBA 3
LBA 2
LBA 1