As disk based backup becomes far more acceptable across a wide range of businesses it looks like the writing is on the wall for the venerable tape drive. [img 77690 /] The key driving force has been the massive increase in disk drive capacities over the past few years along with a commensurate drop in storage costs.
HP’s StorageWorks RDX takes advantage of the fact that 2.5in. small form-factor hard disks are now a viable and affordable option for backup. The RDX offers a simple, removable media solution that enables off-site backup to be brought into the equation.
It consists of a compact chassis with a USB 2.0 port, whilst the SFF disks are mounted inside sturdy removable cartridges. On review is the external model but HP offers an internal USB 2.0 version as well – SATA is not currently an option.
The chassis is very well built and the cartridges 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 can pick the cartridge capacity to suit your current needs and move up to the larger ones as and when required.
Another big advantage over tape is backward and forward compatibility as the RDX cartridge form factor is standardised. The chassis will accept the next generation of higher capacity cartridges and work happily with media that would have been available when RDX was originally launched a few years ago.
One problem with hard disks is their lack of hot-swap support as unless you have them connected to a RAID controller you’ll need to power the host system down first. HP has neatly solved this conundrum as its RDXMon monitoring service enables the cartridge eject button to work under Windows. When you hit the button it releases the drive , permitting it to be safely removed and replaced whilst Windows is running.
HP also provides a simple diagnostic utility that scans the host system for supported devices and shows the currently loaded cartridge. It provides details of the device and cartridge, offers a firmware upgrade tool and runs read/write tests.
For testing we installed the RDX on a Boston Supermicro dual 3GHz Xeon 5160 system loaded with Windows Vista SP1. With the RDXMon utility installed, the drive is seen by Windows as a simple removable media device and cartridges automatically appear ready for use a couple of seconds after loading.
[pb/]
Iometer reporting a 26MB/sec average read throughput but real world speeds were slightly slower - 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 can work with 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 the USB 2.0 model costs over £100 more and only offers 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 the DAT72 deliver a paltry average speed of just under 3MB/sec.
The RDX was also superior to tape for restore operations. Using Retrospect we restored a single Word document near the end of the backup selections, which took 90 seconds for the DAT72 – the RDX did it two seconds. It’s also worth noting that, unlike the old NTBackup Windows utility, Vista’s built in backup tools do not support tape drives.
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.
The RDX currently has very little competition in the SMB removable hard disk market with only Imation’s Odyssey and EMC’s Iomega REV putting up a fight. The Odyssey does cost less but in both cases neither Imation nor Iomega can match the higher capacities of the RDX and both are proprietary. The big advantage of the ProStor RDX technology is that it has a much higher industry support, as along with HP it’s also offered by IBM , Dell and Tandberg Data.
Author: Dave Mitchell
HP StorageWorks RDX Removable Disk Backup review