Recommended Switch Infrastructure For An Hp P4000 San - HP P4000 SAN Technical White Paper

Recommended switch infrastructure for an HP P4000 SAN

HP does not recommend any particular switch for use with HP P4000 SANs. However, there is a set of minimum
switch capabilities that make building a high-performance, high-availability storage network a relatively easy and
cost effective task.
The following are three commonly recommended HP switches, but ultimately you will need to follow the recommended
switch capabilities in Table 1 below which provides guidance for general switch selection based on your specific
needs. As a rule of thumb, any enterprise-class managed switch typically has the capabilities required for most
customer installations.
•
HP E2910 al Switch Series (10/100/1000Base-T & 4 x optional 10GbE)
•
HP A5810-48G Switch (10/100/1000Base-T & 2 x 10GbE)
•
HP E6600 Switch Series (10/100/1000Base-T and 10-GbE SFP+)
For common CLI commands for HP and Cisco switches, please download the HP Networking and Cisco CLI
Reference Guide, which compares many of the common commands in the HP ProVision, Comware 5, and Cisco
operating systems.
Table 1. Minimum recommended switch capabilities for an HP P4000 SAN
Switch capability
Gigabit Ethernet
support
Non-blocking
backplane design
Sufficient per-port buffer
cache
Flow control support
Support for Switch
Stacking
Individual port speed
and duplex setting
* This value can be changed on the HP Networking and Cisco switches to reduce the number of buffers but increase the size of each individual
buffer cache.
Description
Each storage node comes with a minimum of two Gigabit Ethernet ports (802.3ab). For proper
operation of the SAN environment, Gigabit Ethernet support is required for each device in the SAN
infrastructure.
In order to achieve maximum performance on the HP P4000 SAN, it is important to select a switch
that has a fully subscribed backplane, which means that the backplane must be capable of
supporting all full-duplex communication on all ports simultaneously. For instance, if the switch has
24 10 Gb ports, it will require 480 Gb backplane to support full-duplex Gigabit communications.
For optimal switch performance, HP recommends that the switch have at least 512 KB* of buffer
cache per port. Consult your switch manufacturer specifications for the total buffer cache. For
example, if the switch has 48*1 Gb ports, the recommendation is to have at least 24 MB of buffer
cache dedicated to those ports. If the switch aggregates cache among a group of ports (for
example, 1 MB of cache per 8 ports), space your storage nodes and servers appropriately to avoid
cache oversubscription. Many switches can be adjusted in regards to the number of buffers per port
and memory allocated for each buffer. If possible, tune these parameters to increase the available
buffer cache for the storage node ports.
IP storage networks are unique in the amount of sustained bandwidth that is required to maintain
adequate performance levels under heavy workloads. Gigabit Ethernet flow control (802.3x)
technology should be enabled on the switch to eliminate, receive, and/or transmit buffer cache
pressure. The storage nodes should also be set to have flow control auto-negotiated. Flow control is
required when using the MPIO DSM.
For proper management and failover, HP recommends that all switches in your SAN infrastructure
be capable of participating in a stacking mechanism for central administration and control.
Individual switch manufacturer ISL (Inter-Switch Linking) support is required to link all switches in a
SAN infrastructure together. For non-IRF (Intelligent Resilient Framework) switches, the switch should
support designating one or more (through Link Aggregation Groups) ports for inter-switch links.
HP recommends that all ports on the switch, servers and storage nodes be configured to auto-
negotiate duplex and speed settings. Although most switches and NICs will auto-negotiate the
optimal performance setting, if a single port on the IP storage network negotiates a sub-optimal
(100 Mb/s or less and/or half-duplex) setting, performance of the entire SAN performance can be
degraded. Check each switch and NIC port to make sure the auto-negotiation resolves to 1000 or
10,000 Mb/s accordingly with full duplex. P4000 10GbE adapters are configured as 10 Gb, full
duplex only, thus the storage network must be 10 Gb.
3