Product Reviews

The huge gap between the prices of mid-range servers and backup devices has shown no sign of decreasing. PC Pro highlighted this disparity back at the beginning of 1998 (see issue 40, p132), and yet 18 months later we still see a reluctance on the part of high-capacity tape drive manufacturers to reduce prices significantly.

Formed in February 1998 as a spin-off company from Philips Electronics, OnStream's aim was to develop a high-capacity, cost-effective backup solution. The result of its labours is the ADR (Advanced Digital Recording) range of drives. There are four drives available, with the SC30 on review offering a native 15Gb of storage and a 2Mbytes/sec transfer rate, all for a mere £349. The closest competition comes from the DAT DDS-3 format, but these drives invariably cost over twice as much and, as our tests have shown, are a lot slower.

The SC30 uses a multichannel head that simultaneously records up to eight tracks, a technique that is said to improve reliability. OnStream's spatially distributed ECC (error correction code) uses all the tracks to write ECC bits, letting it reconstruct data from damaged areas. OnStream claims this protects data even when an entire track is damaged.

Another feature worthy of note, especially at such a low price, is the drive's embedded servo system. Each tape has special servo tracks positioned

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on each side of the data tracks which are used to keep the head positioned correctly in the event of tape wander. This is also used to identify defective areas on the media. If the servo tracks can't be read, the drive stops writing data and waits until the servo signals reappear.

Available as an internal SCSI drive only, the SC30 is enclosed in a solid steel shell with a single button on the front panel for operating the motorised loading mechanism. An LED in its centre shows activity and drive status. It comes supplied with OnStream's own Echo backup software, which is principally designed for workstation backup and assigns a drive letter to the SC30. This means data can be copied to it using drag and drop. However, Echo is also sophisticated enough to run scheduled backups, and it keeps a full catalogue of each tape's contents to simplify restore operations.

For testing, I installed the SC30 in a Dell PowerEdge 2300 server equipped with dual PII 400MHz processors, 256Mb of memory and Windows NT Server 4. I used Backup Exec for comparison and created a 3.2Gb mish-mash of files typically found on a server. Echo will run under Windows NT, but because it loads a utility that retains control of the drive - stopping the NT driver from loading - you won't be able to use any other backup software.

Real-world performance results were extremely impressive, with the SC30 securing the test data in only 39 minutes at an average speed of 85Mbytes/min. Full verification was even faster, at 97Mbytes/min, while restoring 2Gb of data took 25 minutes at a rate of 96Mbytes/min. In fact, the only drive with similar capacity that can touch the SC30 for speed is Tandberg's SLR6, which returned speeds of between 100 and 109Mbytes/min, but this costs around £200 more.

Overall, OnStream looks to have a winner on its hands with the SC30. It combines good performance, high storage capacity and reliability at an extremely reasonable price.