Easing the backup pain

IF YOU ARE tired of playing the usual backup-to-tape game to protect your company data, a few alternatives are beginning to emerge that replace or complement cartridge-based copies with faster disk-to-disk operations.

The benefits of disk-based backups are clear: faster data protection sessions, reduced downtime, and less exposure to operating errors, which easily translate into lower operating cost and capital investment in tape libraries.

One of the last novelties comes from Unitrends, a company previously known for its Backup Professional and PC Parachute backup and recovery software. The company recently released DPU (Data Protection Unit), a hardware/software combo that promises faster, unattended disk-to-disk copy operations over the network and quick recovery from emergency situations such as a disk failure, all the while keeping the door open for traditional, tape-based backups.

We liked the easy and flexible backup scheduling of the DPU and the powerful crash-recovery options that work on just about any platform and can restore damaged OS volumes connected to a variety of SCSI or IDE (integrated development environment) controllers. Our only perplexity is the company’s choice of network connectivity: Currently, the DPU doesn’t support Gigabit Ethernet, which could improve execution times significantly.

The DPU that we tested had a contained 1U form factor that should easily find a space in even the most crowded racks. Removing the cover reveals a neat layout with motherboard, CPU, and power supply in the back, and bays for three hot-swappable disk drives in the front. We counted 13 fans plus the one on the CPU heat sink, which should keep the temperature inside down but also makes for noisy operations. Our unit mounted two IBM DeskStar 124GB drives, one hosting the Linux 2.4 kernel-based OS, the other reserved for backup operations, which left one bay empty for additional storage.

Installing the DPU was a breeze. We connected the two Ethernet ports to our switch, plugged in keyboard, mouse, and monitor, and we were ready to go. Unitrends preconfigures the unit to meet a customer’s network’s IP range, but should your configuration change, those settings can be easily adjusted. After turning the power on, we started Backup Professional, the bundled software, and were ready to starting backing up data.

Using the Backup Professional software, the DPU can back up and restore volumes or files from most Linux, Unix, and Windows systems. But we limited our test mission to scheduled backups, online restores, and crash recovery on Windows 2000 and Red Hat 7.2 Linux machines — challenges that the DPU met without a hitch. Setting up and configuring your backup clients does, however, require some work and careful planning.

Gentlemen, start your backup

First, we installed the backup software on our servers and clients from the supplied CD. We began from a Red Hat machine. The software installed quickly and without a glitch. Then we were asked the name of the DPU server, which the setup script used to register the new client to the DPU. Back to Backup Professional, we saw our Red Hat machine appear in the client list.

The next step was to assign a backup device for our new client. You can use a tape device (an empty PCI slot on the DPU can host a SCSI controller for that purpose), or you can carve a directory from one of the data volumes. With no tapes on our DPU, we chose an online directory as target device for our backups for that client. A wizard guided us through inputting information such as the volume, the directory to use, and how much space to reserve.

A minor glitch: DPU doesn’t automatically create a backup directory for you. We had to do this manually from a terminal window. Also, DPU uses that space in a round-robin fashion, removing the oldest backup when out of space. Therefore you should plan the appropriate backup directory size for each client. As mentioned, our volumes had a 120GB capacity; but for additional space, you can order a unit that mounts 180GB drives, or you can add multiple DPUs to your environment.

Now it was time for our first backup, which we started by clicking the Backup icon on Backup Professional. Interestingly, you can initiate a backup from the DPU or from the client. Either way, the software will update a central catalog of your backups containing minute details of which files were copied during each session.

We ran several scheduled and impromptu backup and restore sessions for our Linux client without a problem. We also repeated essentially the same setup script on Windows 2000 server and client machines with similarly positive results.

Of course, the DPU’s online copy-to-disk capability offers more flexibility to schedule unattended backups at an appropriate time without concerns about mounting a cartridge or dedicating a tape drive. DPU can handle simultaneous backups (and restores) to the same volume, a feature that a tape device simply cannot deliver.

Road to recovery

Even if you have a full backup, should a storage device fail on your server, restoring the data would not be possible until the OS is reinstalled or copied from a volume image. DPU offers an additional option, Crash Recovery, which addresses that exact situation. To use Crash Recovery, you need to activate a different setting for each server, essentially creating a Linux-bootable recovery diskette with the minimal configuration to access the DPU over the network and your disk devices locally. In addition, you need to execute a different backup, a volume image of your server OS, that the Crash Recovery software will easily restore.

The process is simpler than it sounds: We chose the Crash Recovery option from the menu and then entered the name, the data directory for our copy operations , the network address, and the type of disk controller of our machine. Our boot diskette was ready in about a minute.

Next, we shut down our server and restarted, booting from the recovery diskette. A menu opened and listed various applications available, including the Backup and Restore apps. We chose Backup to create an image copy of our server’s OS volume. Behind the scene, Crash Recovery began sending the image copy of our server volume to the DPU over the network.

It took about 50 minutes to copy our 4GB volume on a 10Mbps connection, thanks to a compression algorithm that shrinks the data by 50 percent. Nevertheless, this is a preventive, time-intensive operation that you should repeat for each critical server in your datacenter. The payback is being able to restore your server to working condition quickly when something disastrous happens, such as a disk failure or corruption.

To simulate the effect of a volume crash, we formatted our server’s disk drive. Now, of course, our machine would not start. Booting from the recovery diskette again, we chose Restore — and crossed our fingers. In about the same time, 50 minutes, our server OS was restored, and our machine could boot again, a sensibly faster and safer alternative than reinstalling the OS from scratch.

Running traditional, tape-based protection for your datacenter often resembles walking a high-standing rope without a net: A hardware failure or a human error can turn the walk into a disaster. Unitrends DPU takes much of that risk out of your datacenter and away from your business at a reasonable cost. It’s a nonexclusive alternative to purchasing more tape drives that is worth considering.