It’s taken a while but iSCSI is starting to offer some serious options for enterprise level storage. Intransa’s IP5000 Storage System is a prime example as it introduces a host of features we’ve not seen before making it a strong challenger to fibre-channel (FC) for handling critical applications.
The entry-level IP5000 system comprises two chassis with the SC5100 1U rack mount controller providing a pair of management modules. The 16-bay DE5400 3U cabinet delivers the storage and Intransa also provides 8-bay models as well. The SC5100 can handle up to six storage enclosures. The system came supplied with eight 200GB Maxtor ATA/133 hard disks but with 250GB drives the IP5000 can support impressive total capacities of either 12TB or 24TB. The controller modules are hot-swappable and run Intransa’s Linux-based StorControl OS from a flash memory card. Each provide four copper Gigabit Ethernet ports and the chassis has dual redundant power supplies.
A number of deployment options are available as all ports on the storage enclosures can be linked to a separate Ethernet switch along with two ports on each controller. One port on each controller presents the storage as iSCSI targets and so is connected to a switch on the LAN. Management access can also be separated by placing Ports 1 and 5 on a separate switch along with the management stations. Alternatively, you can connect the lot together and use VLANs to separate the various components from each other.
We opted for the multiple Ethernet switch route and used a pair of HP ProCurve Gigabit switches for testing. A single management station was connected to the same switch as the target ports and test clients but was configured in a different IP subnet. General management and configuration are handled by Intransa’s Java-based StorControl management utility which offers easy access to the controllers and enclosures. All hard disks are seen as global devices so their physical location is irrelevant. This allows drives on different chassis to be amalgamated into RAID arrays and new drives or enclosures added on demand without affecting normal operations.
Realms are used to group management controllers, disk enclosures and network connections into a single management domain. From StorControl you log on to a specific controller where you can see all associated devices within the same realm. You start by creating virtual volumes and if you use the default policies created by Intransa available physical disks are automatically assigned to the volumes. You don’t choose them yourself and customising the policies means a trip to the CLI. You can opt for basic disks or go for striped arrays, mirrored arrays or combination of both and each can be swiftly selected from a drop-down menu. Intransa’s mirrors offer a distinct advantage over traditional RAID arrays as both drives are visible. You could, for example, create a mirror of a virtual volume and on completion break the mirror and present it to specific clients as a new drive.
There’s also the snapshot feature which provides real-time backup facilities and the snapshot volume can also be presented as an iSCSI target.
Clients on the LAN cannot see any targets unless expressly allowed. Each client logs on to the IP5000 Ethernet port address that provides iSCSI connectivity and its initiator will appear in the StorControl interface. You can then assign selected targets to it and determine read and write access permissions.
For performance testing we used a Windows Server 2003 system with Microsoft’s iSCSI initiator software v1.05. Logging onto a single 10GB striped volume and running Iometer with 64KB transfer requests and 10 outstanding I/Os we saw raw transfer rates settle to an average of 81MB/sec. We then created four separate virtual volumes as basic disks and assigned one disk worker to each one. Running the same test returned an impressive 106MB/sec average transfer rate - close to the limits of Gigabit Ethernet.
The IP5000 shows clearly that iSCSI is now capable of challenging FC in many areas of the enterprise storage market. It can’t compete for raw performance but the features, fault tolerance, security and price offered by Intransa makes it a good, cost-effective storage alternative.
The variety of iSCSI target devices currently on the market and the variations in features and capabilities makes it imperative to decide exactly what you want before buying network storage. Products such as Adaptec’s Storage Array iSA1500 provides easily managed, low cost network storage and limited features but if you want fault tolerance, management and security that’s as close to an FC SAN as it gets the IP5000 should be investigated