Thecus i5500 in Storage appliances

Thecus was the first desktop NAS vendor to incorporate iSCSI support into its higher end apps and with its latest i5500 it goes the whole hog and delivers a pure IP SAN solution to match Buffalo's TeraStation Pro II iSCSI.

The i5500 looks more polished as it uses a similar five-bay chassis to the PC Pro Recommended N5200PRO. You have the same backlit LCD panel at the front and this can be used to manually configure the RAID volumes and network ports. Network options are excellent as the i5500 has a Fast Ethernet port for dedicated management and two separate Gigabit iSCSI data ports.

The web interface is easy enough to use and configuration starts with creating volume groups. These contain selected physical drives plus an assigned RAID array. Next, you create user data volumes (UDVs) which are your iSCSI virtual drives; each volume group can contain multiple drives of varying capacities. Access controls are good as each drive can be assigned to specific iSCSI host initiators or a wildcard entry makes them available to all hosts and you can specify read or read/write access.

Thecus' iSCSI implementation is slightly unusual as the appliance only advertises a single iSCSI node name with all accessible virtual volumes appearing under this as LUNs. This isn't a major issue but as CHAP authentication is applied at the node level it will apply to all hosts and all LUNs. However, you can create multiple user accounts each with their own CHAP secret.

For testing we slotted in a quartet of Western Digital Raptor SATA hard disks and let the quick-start routine create a single RAID0 stripe. Within this volume group we set up four UDVs and made them available to all hosts. A Dell PowerEdge 1950 dual quad-core Xeon server loaded with Windows Server 2003 R2 and Microsoft's iSCSI initiator was called up for host duties.

Performance is superior to Buffalo's appliance with Iometer reporting raw read and write rates of 106MB/sec and 51MB/sec for a single host. With virtual volumes logged into from two servers on different subnets we saw a high cumulative raw read throughput of 197MB/sec. Real-world speeds were also good with copies of a 2.52GB video clip returning read and write speeds of 56MB/sec
and 52MB/sec.

Support for MPIO is touted as a feature although any host that uses Microsoft's iSCSI initiator version 2 and above will have the necessary DSM included as standard. This allows you to create redundant paths to storage volumes by allowing Windows to see the same disk twice, so paths from two network controllers to the same logical drive can co-exist. We had no problems creating a load-balanced redundant link to the app but the lack of instruction in the manual won't impress new users.

With only Buffalo and Thecus offering desktop iSCSI appliances your choices are very limited. If you want one now then the i5500 is the far superior product but it's difficult to see how Thecus can justify the high price.

Author: Dave Mitchell