IBM Midrange System DS4000 Series Hardware Manual page 136

For the number of maximum storage partitions for a specific model, see Table 4-3. Note that
on DS5000 models that the number of partitions also depends on the premium feature
licenses that have been purchased.
Table 4-3 LUN restrictions
Operating system
Windows Server 2003
Windows Server 2008
HP-UX
AIX
Linux
Every mapping of a logical drive to a new host or host group creates a new storage partition.
If additional logical drives are required for an existing host or host group, a new storage
partition is not required. For example, a cluster with two nodes with redundant I/O paths are
configured as one host group with two hosts. Each host has two host ports for redundancy.
Several logical drives are mapped to this host group. All these components represent one
storage partition. If another single host system is attached to the same storage system and
different logical drives mapped to that host, another storage partition must be created for it. If
a new logical drive is created and mapped it to either the cluster or the single host, it uses an
existing storage partition.
For a step-by-step guide, see 4.1.4, "Storage partitioning" on page 116.
Note: The are limitations as to how many logical drives you can map per host. DS5000
series storage subsystems will support up to 256 LUNs (including the access LUN) per
partition (although there are also restrictions, depending on the host operating system) and
a maximum of two partitions per host. Keep these limitations in mind when planning the
DS5000 storage subsystem installation.
Storage partitioning considerations
In a heterogeneous environment, the "access" logical drive is mapped only to the default host
group. If in-band management is being used, then the access logical drive must be mapped to
the storage partition for the managing host.
In a security-sensitive environment, you can also assign the access logical drive to a
particular storage partition and ensure host-based management access only through the
servers in this storage partition. In this environment, you can assign a password to the
storage system as well.
Note: Each host with uniquely assigned storage will use a storage partition. Each host
group with uniquely assigned storage will also use an additional storage partition.
For Fibre Channel attachments, in order to do the storage partitioning correctly, you need the
WWN of your HBAs. Mapping is done on a WWN basis. Depending on your HBA, you can
obtain the WWN either from the BIOS or QLogic SANsurfer tool if you have QLogic cards.
Emulex adapters and IBM adapters for IBM System p and IBM System i® servers have a
sticker on the back of the card. The WWN is also usually printed on the adapter itself or the
box in which the adapter was shipped.
118
IBM Midrange System Storage Hardware Guide
Maximum number of LUNs supported per
partition
255
255
127
255
255