Spotlight on midrange arrays


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Despite its SATA drives and low price tag, the Thunder 9520V boasts an impressive list of software.
Hitachi Data Systems Thunder 9520V
Last fall, Hitachi Data Systems (HDS) Corp. introduced the 9520V, an all-SATA version of its Thunder 9500 family geared toward small- to medium-sized businesses (SMBs). It can be bought with single or dual controllers, up to 2GB of cache and can support up to 59 250GB disks for a total of 13TB.

Despite being a SATA box, the 9520V has much in common with the rest of the Thunder family, the 9585V and 9570V. Virtual ports allow users to connect many more hosts to the array than just through its physical ports (four front-end 2Gb/sec ports, with subscription of around 2.5 hosts per port). The 9520V also supports almost the entire library of Thunder software--an important consideration for current HDS customers.

Missing from the 9520V's software arsenal is TrueCopy Remote Replication, a real-time synchronous data replication function that HDS didn't port because it's "cache-intensive," says Jeff Hill, HDS' director of infrastructure product marketing. The 9520V is limited to only 2GB

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total cache. TrueCopy is also cash-intensive--pun intended--and not typically needed by SMB customers, Hill adds. A dual-controller starter configuration with 3.4TB of raw capacity and resource management software costs between $22,000 and $24,000.

HDS has gone to great lengths to make sure the 9520V is no less reliable than its other models, despite its use of SATA drives. Unlike EMC's AX100, a competitive product, it can be equipped with dual controllers--a high-availability feature. Furthermore, HDS has done extensive work to enhance the reliability and lifespan of SATA drives by adding features such as verify-on-write. After periods of extended inactivity, disk drive heads are lifted or parked to prolong disk drive life.

Just because the 9520V has been dubbed an SMB product doesn't mean that's where it will always end up. "We expect to sell some units [into enterprise data centers] as part of a tiered storage infrastructure," says Karen Sigman, HDS' vice president of global channels. To that end, it's important to note that the 9520V is one of the arrays supported by the HDS TagmaStore Universal Storage Platform, which can virtualize certain storage assets in its domain.

IBM's new array borrows heavily from its server architectures and broadens the definition of midrange.
IBM DS6000
When IBM Corp. introduced the DS6000 last fall, it had to share the stage with its more muscular sibling, the high-end DS8000. And while it was expected that the DS8000, with its partitioning capabilities and enterprise-class capacity and performance, would garner most of the kudos, it was the DS6000's exceptional modularity that grabbed the spotlight.

The DS6000 effectively stretches the concept of a midrange storage system downward and upward. In its most modest configuration, it houses a mere 292GB of disk space, but can grow up to 74TB, treading into enterprise territory.

Craig Butler, IBM brand manager for midrange storage products, insists the DS6000 is at the bottom of the enterprise class, while IBM's older DS4500--part of the FAStT product line--is at the top of the midrange class (see IBM's "more choice" marketing plan).

In building the DS6000, IBM borrowed heavily from its server technologies, most notably incorporating the same 64-bit PowerPC processors used in its eSeries servers. The result is a base system that will fit in a single 3U slot in an industry standard 19-inch rack. Expansion units--each housing up to 16 additional drives--are similarly sized and a fully tricked-out rack can accommodate a maximum of 248 drives.

IBM also says the DS6000 can be installed in about an hour without onsite service personnel. Upgrades and maintenance can be handled by users with the aid of diagnostic and self-healing features that have been road-tested in IBM servers. Upgraded management software, now called IBM TotalStorage DS Storage Manager, is enhanced with improved interfaces and wizards to help users take care of configuration, operations and maintenance.

The DS6000's operating system code is nearly identical to that of the DS8000, which runs about three-quarters of the ESS series' code. This ensures operational and functional compatibility among DS and ESS machines, allowing users to run nearly all the same software across systems. While this is an important development technically, IBM's allowing the DS6000 to run the same applications as its enterprise-class sibling dramatically ups the ante for all midrange arrays regarding more functionality at a lower cost. In addition, the DS6000 supports mainframes and open-systems servers, which is rare among midrange storage systems.

The DS6000 is one of the most expandable, modular storage arrays available. All that's missing is a track record. The DS6000 is still too new to rate its success against other vendors' offerings and IBM's own popular FAStT arrays, which it's positioned to replace.

Isilon's clustered storage system boasts a distributed file system.
Isilon IQ
Seattle-based Isilon Systems Inc.'s IQ modular arrays are specially designed to store large image files. Isilon uses a symmetrical clustering architecture where all nodes act as peers to deliver a modular approach to capacity and performance scaling.

The Isilon IQ comes in two models--the IQ 1440 and the IQ 2250--differentiated only by their storage capacities. The basic building blocks of both models are 2U rack-mountable nodes with their own Intel Xeon 2.8GHz processor, 4GB of cache, disks and four GbE NICs. The two models have an initial configuration consisting of three nodes; both are expandable to 21 nodes, which fill a single rack. In this manner, the IQ 1440 scales from a base system of 4.3TB to 30.2TB, while the higher-end 2250 goes from 6.75TB to a maximum capacity of 47.3TB.

Because each node is essentially a fully configured storage system, performance increases almost linearly as nodes are added to the cluster. Adding a node is a simple affair, requiring little more than plugging in power and the Ethernet connection. In its report on the Isilon IQ, the Milford, MA-based Enterprise Strategy Group noted that adding a new node "takes less time than setting up a DVD player."

As a new node is added, the cluster members automatically acknowledge each other and begin working as a unit. When a node enters the cluster, it inherits existing configuration information and policies. Isilon's AutoBalance feature then redistributes stored data among all active nodes. All storage is pooled and managed by a single file system, the OneFS 3.0 distributed file system.

The IQ's ease of use and scalability, combined with a starting price of less than $50,000 for a three-node cluster, makes it an attractive option. Some users might balk at committing to a storage system based on ATA disks, but Isilon's data protection schemes seem to mitigate some of that risk. In any event, the company says the next generation of the IQ will support SATA disks. Perhaps then Isilon will boost the maximum capacity of the IQ system to the levels offered by other midrange clustered systems, especially if it wants to be a serious player in the rapidly growing digital imaging content field.

This was first published in March 2005

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