HP StorageWorks RDX Removable Disk Backup System in Backup devices

Tape has had its day as a solution for data backup in small businesses, as compared with the latest hard disk-based products it's too slow and initial outlay is far higher. HP's StorageWorks RDX is a prime example, as this compact unit combines high-capacity hard disks in removable cartridges and delivers a superior performance for backup and restore operations.

On review is the external model, but HP offers an internal version as well. Only USB2 is supported as, unlike Tandberg's QuickStor, HP doesn't offer a SATA model. The sturdy cartridges have 2.5in SATA hard disks mounted inside, and are rated as capable of shrugging off a drop onto a hard surface from one metre.

The kit on review includes a 160GB disk cartridge, but HP also offers 320GB and 500GB versions. Either way, you pick the cartridge capacity to suit your current needs and move up to the larger ones when required without having to buy a new drive unit - as you would with tape.

For testing, we installed the RDX on a Boston Supermicro dual 3GHz Xeon 5160 system loaded with Windows Vista SP1. To make the drive removable you load the RDXMon monitoring service, which allows the cartridge eject button to work under Windows. HP also provides a diagnostic utility that scans the host system for supported devices and shows the currently loaded cartridge. It also offers a firmware upgrade tool and can run read/write tests.

Performance was below that quoted, with Iometer reporting a 26MB/sec average read throughput. Real-world speeds were slightly slower, as copying a 2.52GB video clip returned read and write speeds of 25.8MB/sec and 20MB/sec. The RDX is compatible with any backup software that supports removable drives, and we tested with EMC Retrospect. Securing a 13.5GB test folder with nearly 15,000 files in it returned a much lower write speed of 7.5MB/sec.

The closest tape device in terms of price is the DAT72, although even HP's USB2 model costs over £100 more and offers only a native 36GB on 4mm tape cartridges. We installed a USB external model on the server to compare performance, and backing up the same test data using Retrospect saw it deliver an average speed of just below 3MB/sec.

The RDX is also superior to tape for restore operations. Using Retrospect we restored a single Word document near the end of the backup selections, which took 1min 30secs for the DAT72 - the RDX did it two seconds.

The kit comes with HP's CDP (continuous data protection) software, which does precisely what it says on the tin. Once installed, it asks for a cartridge to be loaded, whereupon it proceeds to back up all partitions on the host system. From this point on, it automatically backs up files as they are created or modified, and creates a separate partition in Windows Explorer from where you can view secured data and carry out drag-and-drop restorations.

For small business, tape backup really is a non-starter, as it's too expensive and too slow - Vista's built-in backup tools don't support tape devices either. The StorageWorks RDX is a much slicker solution, as it's faster and offers lower storage costs, although if you want a bit more speed then we recommend Tandberg's QuickStor SATA model, which is slightly faster.

Author: Dave Mitchell