206 IBM eX5 Implementation Guide
Figure 5-21 RAID choices using the LSI configuration utility
The following options are presented:
Create IM Volume: Creates a RAID-1 array
RAID 1 drives are mirrored on a 1 to 1 ratio. If one drive fails, the other drive takes over
automatically and keeps the system running. However, in this configuration, you lose 50%
of your disk space with one of the drives being used as a mirrored image.
The stripe size is 64 Kb and cannot be altered.
This option also affects the performance on the drives, because all data has to be written
twice, once per drive. See the performance chart in Figure 5-22 on page 207 for details.
Create IME Volume: Creates a RAID-1E array
This option requires three drives, so it is not available in the HX5.
Create IS Volume: Creates a RAID-0 array
RAID 0 or the Integrated Striping (IS) volume, as shown in LSI, is one of the faster
performing disk arrays because read and write sectors of data are interleaved between
multiple drives. The downside to this configuration is immediate failure if one drive fails.
There is no redundancy.
In a RAID-0, you also keep the full size of both drives. Identical size drives are
recommended for performance, as well as data storage efficiency.
The stripe size is 64 Kb and cannot be altered.
We provide the instructions to create an array in 8.4, “Local storage considerations and array
setup” on page 385.