Thecus i8500 review

Most small businesses looking for affordable IP SANs have to make do with desktop NAS appliances that offer iSCSI targets as an extra. Thecus is one of the few vendors in this sector that offers pure iSCSI appliances, with its i5500 five-bay desktop box offering a good turn of speed - but at a price.

The i8500 IP SAN rack appliance moves the focus to larger businesses. This 2U rack appliance supports up to eight hot-swap SATA drives and includes superior hardware redundancy. Like the i5500, it uses an Xscale processor with an 800MHz core and has two Gigabit data ports, but memory has been doubled to 1GB.

Power is handled by a pair of 350W hot-swap supplies. Thecus offers an optional battery backup module for the RAID controller, which also supports an impressive selection of array types. With two data ports available, you can use MPIO (multi-path I/O) to define multiple, redundant paths to iSCSI targets.

A dedicated Fast Ethernet port is used for management access, and a wizard on the simple web interface offers a choice of arrays basesd on the number of drives it finds. For testing we loaded a quartet of 1TB WD GreenPower drives and opted for a RAID5 array.

Arrays are called RAID groups (RGs), and you can have more than one in the appliance. Within these RGs you create virtual disks (VDs), which are your iSCSI virtual volumes, and each RG can contain multiple VDs of varying capacities. Access controls are good; each VD can be assigned to specific iSCSI initiators, or wildcard entry makes them available to all hosts. You can also specify read or read/write access.

The i8500 has a single entity, or node name, which can't be modified. This means hosts see the same target name when they log in, but only the volumes they're permitted to access will be shown underneath. CHAP authentication is also applied at the node level, so this single setting will apply to all hosts, but you can create multiple user accounts, each with their own CHAP secret.

The i8500 supports up to 256 virtual disks. A snapshot service takes point-in-time backups of selected volumes. You can recover volumes with the rollback feature and attach snapshots to LUNs and present them as new targets.

For testing we used a pair of Xeon 5500 servers running Windows Server 2008. With one host logged in to a 50GB target, we saw impressive read and write speeds of 111MB/sec and 104MB/sec. With two servers logged in to dedicated virtual volumes from different data ports we saw a cumulative raw read throughput of 198MB/sec. Real-world speeds were respectable, with copies of a 2.52GB video clip returning read and write speeds of 68MB/sec and 66MB/sec.

There's no denying the i8500 is a speed merchant offering a good range of IP SAN features. However, as with the i5500, it's comparatively expensive. The A-Listed RS8 IP-4 appliance from Enhance Technology is only a few pounds more and offers twice as many iSCSI data ports, SAS and SATA support and a vastly superior expansion potential.

Author: Dave Mitchell