LeftHand Networks SAN/iQ 7 review

In the circus that is network storage there's a new main attraction taking centre stage. For far too long iSCSI has had to wait in the wings but no longer as small to medium businesses and mid-sized enterprises realise that it's a far more cost-effective alternative to overpriced, overrated and overly complex fibre channel solutions.

Formed in 1999, LeftHand Networks has focused entirely on iSCSI and its latest SAN/iQ 7 Storage Software Platform aims to deliver a range of enterprise level storage features and fault tolerance. The backend system is where all the action is and SAN/iQ scores highly here as, unlike many FC products, it doesn't tie you to proprietary hardware. The software is currently certified with two HP ProLiants and a single IBM System server and LeftHand Networks offers its own NSM 160 appliance. The software is implemented as a customised Linux kernel and installation on your chosen certified platform only takes a few minutes. Another advantage of this modus operandi is you can opt for any disk interface you fancy.

The main concept behind SAN/iQ 7 is clustering over Ethernet which allows you to gather together multiple physical servers and present all their storage as a single pool. Fault tolerance starts at the server level as SAN/iQ can configure and manage certified RAID controllers and defaults to hardware managed RAID-5 on each server.

The storage pool is then carved up into virtual volumes which are automatically striped across all drives and server nodes contained in the cluster. SAN/iQ is priced per node but there are no limits to how many a cluster can contain. FC SAN solutions that require a head unit are restricted as only so many disk arrays can be added. SAN/iQ allows you to keep on adding new nodes to a cluster and the data will be automatically re-striped across them.

Clusters are managed using an MMC snap-in and we found the central administrative console (CMC) easy enough to use. You start by allowing CMC to auto-discover all modules where you can select each one and configure the RAID functions. Next, you add the modules to management groups which define their physical location and allow them to communicate status information to each other. Now you create your clusters and provide them with a virtual IP address. All physical network ports in the cluster are gathered together in a fat trunk with fault tolerance and load balancing and all access to virtual storage is over this one IP address.

A valuable feature of SAN/iQ is the base price includes four key technologies. Synchronous replication, or network RAID, functions at the virtual volume level and is similar to mirroring. However, as data is replicated it is written across the same cluster but skewed so the same blocks don't use the same server. During volume creation you have options for two-way and three-way replication where the former can survive the loss of one physical server and the latter can handle the loss of two.

Next up is thin provisioning which is designed to minimise wasted disk space. You decide how big your virtual volume should be but on creation it only starts as a 128MB physical volume. This grows dynamically in 128MB increments as demand dictates and you can set thresholds to warn when the virtual volume is filling up. If this happens you just increase its size from the CMC.

For access control multiple volumes can be added to a single list, read or read/write access can be set and authentication groups used to determine which initiators are allowed to access the targets. We have one minor complaint here as clusters cannot automatically detect available initiators so you'll have to enter them manually.