4.1.0 HP PolyServe Matrix Server administration guide (T5392-96073, October 2010)

Maximum length for disk UIDs
The maximum length for a Matrix Server disk UID is 128 characters. If a disk UID
exceeds this limit, Matrix Server will not be able to import the disk into the matrix. If
you are using a disk array such as iSCSI that allows you to specify a disk volume
name as part of the UID, be sure that the total UID does not contain more than 128
characters.
Restriction for disk partitions
Do not delete disk partitions on LUNs accessed by Matrix Server. The Windows
operating system renumbers partitions when a lower-numbered partition is deleted.
Matrix Server uses the partition number when it is identifying membership partitions
and dynamic volumes. Changes to the partition numbers will causes failures, as
Matrix Server cannot locate the correct data.
Disk partition alignment
Many disk arrays are sensitive to misaligned I/O operations and require I/O to be
aligned on block boundaries for performance reasons. For example, an array may
“prefer” to have I/O operations occur on natural block boundaries, such as 4-KB
blocks. If a partition starts at a non-block boundary, a single logical write can span
more physical blocks that it would on a partition starting on a block boundary,
resulting in additional I/O operations. The exact alignment characteristics vary by
manufacturer and model; consult your storage vendor for alignment recommendations.
This issue occurs because the Windows partition table causes space to be reserved
at the start of the LUN, which can cause a misalignment with the array’s storage. If
your storage array is affected by this issue, the simplest way to avoid the situation
is to create an unused partition at the start of the LUN and then ensure that the second
partition starts on an aligned boundary. The Windows Logical Disk Manager or
utilities such as diskpart can be used to create the partitions.
Import SAN disks
SAN disks to be used for PSFS filesystems must be imported into the cluster. This step
gives the cluster control over access to the disks. Before importing disks, you should
be aware of the following:
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