Review: HP Virtual SAN Appliance teaches dumb storage new tricks

HP’s LeftHand P4000 Virtual SAN Appliance offers a wealth of flexibility with a few caveats

Since Hewlett-Packard acquired LeftHand Networks in 2008, it has continued to develop LeftHand's complete line of software-based iSCSI storage under the HP LeftHand P4000-series moniker. Based on the feature-rich SAN/iQ 9.5 software platform, the currently available P4000 G2 series includes a range of different physical form factors based on HP's ProLiant server line, as well as the virtualized P4000 VSA (Virtual SAN Appliance), which runs on VMware vSphere or Microsoft Hyper-V.

At its heart, the P4000 VSA is simply a virtualized (and thus hardware agnostic) version of the same SAN/iQ software that powers its physical brethren. Though the virtualized version comes with notable scalability limitations, it offers a great deal of flexibility in configuring storage either in concert with physical P4000-series SANs or on its own as a purely virtual SAN.

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Use cases for the P4000 VSA are wide and varied, including everything from utilizing direct-attached storage to implement redundant shared storage in small-business environments to allowing single-host remote offices to asynchronously replicate back to a headquarters site for disaster recovery purposes. Plus, given that the P4000 VSA can utilize any storage hardware supported by its host hypervisor, the VSA can be used to breathe new life into outdated or retired storage platforms, be they DAS-, NAS-, or SAN-based.

P4000 VSA feeds and speeds
As noted, the HP P4000 VSA has nearly all of the same features as its physical counterparts, including local synchronous (clustered) replication, multisite synchronous replication (stretched clustering), remote asynchronous replication, demand-allocated snapshots with application-awareness, and thin provisioning. All storage access is enabled through the use of standards-based iSCSI, and a wide range of operating systems is supported.

This list includes virtualization platforms such as VMware vSphere and Microsoft Hyper-V. The P4000 VSA can both run on and support connections from these hypervisors at the same time, allowing the VSA to abstract direct or SAN-attached storage and offer it back to the hosts as feature-rich shared storage.

The P4000 VSA does have some limitations not found in the rest of the P4000 series. Those include a maximum storage assignment of 10TB per VSA (attached in up to five 2TB virtual disks) and no support for multicore vSMP. Considering the increasing use of flash-based acceleration and SAN/iQ's nearly complete support for VMware's VAAI API extensions (which allow virtual machine cloning and other VM-related storage operations to be shifted onto the storage array), the absence of vSMP support is a substantial limitation.

Given that each VSA draws on only one virtual CPU core, it is not very difficult to drive the VSA to high CPU utilization under extremely high-bandwidth storage workloads. Thus, the VSA may not be a great choice for infrastructures that regularly experience those kinds of loads. HP has indicated this restriction is likely to be lifted in future releases. 

Test Center Scorecard
HP LeftHand P4000 Virtual SAN Appliance8898108


Very Good

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