HP StorageWorks SAN Virtualization Services Platform Best Practices Guide (5697-0935, May 2011)

SVSP path limits
SVSP has a limited number of supported front-end and back-end paths. To avoid unpredictable
results, ensure that your configuration does not exceed these limits (see Figure 7 (page 16)).
DPM paths to back-end LUs
The DPM supports 4096 PSCs (paths to storage controllers). Use the following formula to calculate
the number of PSCs in your environment: #_DPM_ports * #_array_ports * #_BELUs) = # PSCs
For example: 4 DPM ports * 2 array ports *96 BELUs = 768 PSCs
You can distribute the back-end LUs across multiple arrays by zoning the DPM back-end ports to
a subset of controller ports, depending on the number of quads.
DPM connections to front-end virtual disks
Each DPM supports a maximum of 8192 front-end presentations (referred to as kdisks). Use the
following formula to calculate the number of kdsiks for your environment: #_DPM_ports *
#_host_ports * #_Vdisks = # kdisks
You should not consume all 8192 kdisks per DPM. A buffer is needed to allow for phantoms and
quarantined virtual disks.
Remember that each DPM kdisk represents an array virtual disk. Each storage array has its own
limit as to the number of virtual disks it supports, so you must be careful when planning the total
number of kdisks in your configuration in order to not exceed an array's limit. For example, the
HP EVA array supports up to 4096 virtual disks. See your array vendor documentation for more
information.
Figure 7 (page 16) illustrates the limits and formulas for calculating the DPM front-end presentations
(red arrows) and the back-end paths (blue arrrows).
Figure 7 Maximizing DPM resources
Array front-end ports
Each storage array supports a maximum of front-end ports. Remember that when you are calculating
the number of SVSP back-end ports in your configuration, this is the same as considering the number
of array front-end ports needed. Be sure you do not exceed the array front-end port maximums.
See Figure 8 (page 17) for the formula for array port limitations.
16 Fabric topology