HP StorageWorks External Storage XP user guide for the XP12000, XP10000, SVS200 (T1706-96009, October 2007)

Figure 75 Defining MSA array objects with the ACU
Calculating MSA LU size and defining LUs
The ACU used for configuring the MSA uses an optimization algorithm to calculate the user size of a new
LU given a user-specified size in MB (Figure 76). Because you cannot bypass or disable the optimization
algorithm,youmustcompensateforthisoptimizationsothatMSALUsarecreatedatthecorrectsize.
When requesting a new LU through the ACU, make the request 2 to 3 MB larger than needed for
presentation to the XP12000/XP10000/SVS200. For example, suppose you want to create a 40 GB
(40960 MB) LU on the MSA for use as XP12000/XP10000/SVS200 external storage. If you request only
the exact size needed, the ACU optimizes the LU to a size of 40959 MB, which is 1 MB smaller than
needed. In this case, the optimization algorithm the ACU uses can be compensated for by specifying a
size of 40963 MB, which results in the correct size of 40960 MB (40 GB).
Figure 76 Defining MSA LUs with ACU
Selective Storage Presentation
You must institute LUN security on MSAs using the ACU Selective Storage Presentation (SSP) feature
(Figure 77). Use SSP to limit access to individual MSA LUs (in this case, logical drives 1 and 2) by
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