Your next job is to create volume groups (VGs) where you select physical drives and decide on a RAID array for them. Multiple arrays are supported and there are an impressive range of choices with dual drive redundant RAID-6 at the top of the menu. Within each VG you now create multiple user data volumes (UDVs) which will be your iSCSI virtual volumes where each is assigned its own LUN. You can decide on the initial size of each one and it’s worth keeping some spare space set aside within each VG as UDVs can be expanded on the fly. All you do is select their capacity in the UDV list and enter a new value whereupon it will be increased without requiring the appliance to be rebooted.
For access controls you use the Attach menu option where you can allow all hosts to use them by entering a wildcard or add specific initiator names. Usefully, you can determine read and write privileges for each individual initiator. Considering the price we would have expected to see volume snapshots but these are not currently available on the i5500.
Fault tolerant links to the appliance using MPIO (multi-path I/O) are supported. This allows Windows hosts to see the same disk twice so paths from two network controllers to the same UDV can be created. These are easy to create if you know how but don’t expect any help from Thecus as its manual is almost devoid of instruction for MPIO.
To test the appliance we called up Dell PowerEdge 1950 quad-core Xeon and Boston Supermicro dual-core Xeon servers both loaded with Windows Server 2003 R2 and Microsoft’s iSCSI initiator. After adding the target portal we could see the appliance’s single node as a target and once logged on all available LUNs appeared as new local hard disks ready for action.
The i5500 is certainly a speed demon as with Iometer running on the Dell server we saw it return average raw read rates of 111MB/sec which is close to the best you’re likely to see over a single Gigabit connection. With the second server logged on to its own UDV on the other data port we then saw Iometer return a cumulative read throughput of 196MB/sec. Real world speeds are equally impressive as copying a 2.52GB video clip between server and appliance delivered read and write speeds of 64MB/sec and 60MB/sec respectively.
The only competition to the i5500 comes from Buffalo’s TeraStation Pro II iSCSI and although that four bay appliance costs a lot less than the i5500 we felt it was ultimately flawed. Thecus is a clear winner for presentation, performance and features but if you want iSCSI on the desktop be prepared to pay for the privilege.
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