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HP StoreVirtual

storage node

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storage node

HP StoreVirtual

storage node

HP StoreVirtual

storage node

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Hyper-V/vSphere FOM

Site/Rack 1 Site/Rack 2

Site/Rack 3

HP StoreVirtual

Multi-site Cluster

Technical white paper | HP StoreVirtual 4000 Storage

Multi-site cluster networking requirements

Multi-site clusters in HP StoreVirtual enable block level synchronous data replication between sites using Network RAID.

Site-awareness for server and storage systems is built in to multi-site clusters. A multi-site cluster can have up to three

sites. As volumes in a multi-site cluster span all sites, each site has the same number of storage nodes and volumes

in these environments should always be protected using Network RAID (Network RAID 10 for clusters with two sites;

Network RAID 10+1 for clusters stretching three sites).

Figure 7. Typical multi-site cluster environment

The multi-site cluster conguration in gure 7 is typical for customers who want to replicate data synchronously between

two data center. HP StoreVirtual Fail-over Manager, which is ideally installed in a third site, provides quorum in the event

of a site failure. For more information, please refer to the Specialized Manager section in the HP StoreVirtual User Guide.

From a networking standpoint, there are various options to achieve resiliency, it is however recommended to use

multiple, aggregated links between data centers.

The two primary factors that contribute to the health of a multi-site cluster are network latency and bandwidth. High

network latency is a primary cause of slow I/O performance, or worse case iSCSI target disconnects. When designing

a network for multi-site clusters, latency should be kept to a minimum; HP recommends a round trip latency of less

than two milliseconds (2 ms). Focus on reducing latency throughout the design from end-to-end, while taking into

consideration the following:

• Distance between sites—make certain distance between all clustered sites meets the 2 ms requirement

• Number of routed hops between sites—each router or switch in the data path adds delay as the packet is received,

processed, and then forwarded

• Advanced network features—rewalls, NAT devices, QoS, or access lists add latency

HP Storevirtual 4000 White Paper

Other manuals for HP Storevirtual 4000