Product Reviews

It may have been announced at the beginning of 2005, but 4Gb/sec Fibre Channel (FC) technology hasn't exactly set the storage world alight. Most products have languished in relative obscurity. The same can't be said for iSCSI (Internet SCSI). PC Pro Enterprise has brought you hands-on reviews of a raft of compliant storage products that show clearly how this technology is maturing. And now we bring you EqualLogic's PS300E, which moves iSCSI up another gear. The PS300E delivers a range of impressive features, stunning performance and all at a price point that similar FC products can't hope to compete with.

Storage capacity is first on the agenda, as this compact 3U chassis delivers 14 hot-swap bays and comes fully populated with the latest 500GB Hitachi 3Gb/sec SATA 2 drives for a total of 7TB. Fault tolerance is in abundance too. The PS300E comes with a pair of hot-swap power supplies and primary and secondary hot-swap controller units. These deliver support for RAID10 and 50 arrays, and RAID functions are synchronised across both controllers so you can lose one without any impact on operations. Three Gigabit Ethernet network ports are available for use on the primary controller, and you can use either copper or fibre connections, although you'll need to source the fibre SFPs separately. A smart feature is that as you bring more ports online, the controller automatically implements load balancing for a theoretical maximum throughput of 3Gb/sec. The ports on the secondary controller are available for creating redundant network paths.

In EqualLogic's world, all physical arrays, or members, are gathered together and presented to the network as logical storage pools, or groups. The appliance manages its own local RAID arrays, but storage on all members is made available as a single entity. You can use this space to create volumes and present them as iSCSI targets, but data within each volume is spread across all disks and members. The big advantage is that new arrays can quickly be added to the group, allowing storage to be increased easily with demand.

EqualLogic claims a PS300E can be up and running within 20 minutes from unpacking, and we can confirm this to be the case. You start with a CLI session into the primary controller, where you define it as a member and

Further management is via the Java-based web console, which is far better designed than that offered by Reldata. There's not so much as a whiff of the underlying Linux kernel. All group members can be viewed from the same console, which provides full access to all further configuration and provides plenty of operational information about all hardware components. With another PS300E on the bench, we found it easy enough to add a second member to our group. Removing it will cause all data to be moved to existing members before it's released. As you'd expect, volume snapshots offer good backup facilities, but EqualLogic's replication techniques provide excellent fault tolerance and disaster-recovery capabilities. Essentially, this takes snapshots of selected volumes and stores them within other groups called replication partners. Again, this is simple to set up and you can opt for one-way replication to another group, bidirectional replication between groups, or you designate one group as a central location to which multiple groups can be replicated. If a volume is lost or damaged, you just clone a copy of the replicated volume or promote it as a new volume.

For testing, we connected a single member to our copper Gigabit Ethernet network and created an eight-disk RAID10 array for performance. We then created a 50GB volume and used a single Gigabit connection from the appliance. Starting with a single dual-Xeon Windows Server 2003 system, we logged on to the target using Microsoft's freely available iSCSI Initiator 2. With the open-source Iometer configured with two disk workers, 64KB sequential read transfer requests and ten outstanding I/Os, we saw it report a truly impressive raw read throughput of 112MB/sec. Adding a second Gigabit connection and logging onto the same volume from a second server, Iometer returned a cumulative throughput of 214MB/sec. Finally, with the third Gigabit port connected and a third server in the picture, we saw the three instances of Iometer report a cumulative throughput of 300.5MB/sec, confirming EqualLogic's performance claims.

It's true that for some time iSCSI hasn't been viewed as a replacement for FC. But we've seen 4Gb/sec FC suffering from high prices and an indifferent marketing campaign, and it's likely 10Gb/sec FC will go the same way. In contrast, EqualLogic delivers a superb range of features backed up by top performance. With 10Gb Ethernet products becoming ever more affordable, the PS300E provides some compelling arguments as an alternative to FC and also as a replacement.