Many companies would embrace the superior performance and enhanced reliability of clustered storage were it not for the fear that adoption would cost a fortune and lock them into proprietary hardware.
Although that perception is, unfortunately, all too often justified, LeftHand Networks has been offering for quite some time a clustered storage solution dubbed SAN/iQ that runs not only on proprietary hardware but on plain vanilla gear such as HP ProLiant servers. Further, it offers a range of much-needed features including replicas and snapshots. SAN/iQ also offers a set of powerful automated features, such as load balancing and reallocation of existing volumes across nodes, which remove significant burden and cost from storage administration.
Last fall, LeftHand released SAN/iQ 6.6, adding larger disk drives to its clustering capabilities, as well as a redesigned management console with a treelike interface that makes administering a storage cluster more intuitive.
In my test environment, I had four HP ProLiant DL380 G4 servers, each mounting six SCSI drives with 146GB capacity. The fifth machine in my cluster was an NSM 260 (Network Storage Module), a proprietary storage array from LeftHand with 12 SATA drives of 250GB capacity. Each machine was running LeftHand Networks SAN/iQ, which made each of them an active node of the clustered iSCSI storage network.
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Admins can access the system’s various features via SAN/iQ’s management console, a Java application that runs either on a Windows or Linux machine connected to the iSCSI network. Through the console, admins can combine nodes into a cluster; create a new volume from that pool of storage and assign it to an application server; and set the level of data redundancy for each volume and, if needed, limit the bandwidth used for background tasks such as restriping a volume to a new node.
The console has numerous wizards that facilitate just about any administrative task. In addition, SAN/iQ creates a level of abstraction from the storage device that makes working on an HP machine or on the LeftHand proprietary NSM equally seamless. That simplicity of management, however, can unleash some powerful features, such as an unlimited number of snapshots that makes optimum use of space by copying only the delta of changed data.
Another great feature automatically maintains as many as three copies of the same replica on different nodes inside the cluster to protect from simultaneous enclosure failures.
Mario Apicella is senior analyst of the InfoWorld Test Center.
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