Plan for the worst, hope for the best: backup & disaster recovery, Part 2.(Disaster Recovery & Backup/Restore)

In March CTR, Part 1 stressed the importance of regular periodic backups with disaster prevention in mind, and a focus on the ultimate goal of disaster recovery while implementing a plan for disaster prevention.

Hardware

The device selected for backup is fundamental to any successful plan. In the old days, minicomputer user's choices were limited to using relatively small removable disk and open reel tape (first 1600bpi & then 6250bpi drives). In today's backup landscape, while there are many more devices to choose from, the same old conundrum applies as back in the early days--spend a lot to get the best, or buy a cheaper alternative and potentially pay the price in other ways. Bottom line, the device needs to be of sufficient size and speed to allow a full system backup in a reasonable period of time. Choices for users have expanded over the years from single tape QIC, 4MM and 8MM drives, to DAT5, AIT, Super DLT and LTO2 drives, in single unit or autoloader configurations, that offer mind boggling capacities and speeds when compared to what was available even five years ago.

A good example of the latest and greatest hardware is the pending release of a new LTO2 drive slated for this summer with a native capacity of 400GB on a single tape. As usual, this drive will have built-in compression logic and will be quoted (using 2:1 compression) as a 800GB capacity drive. Whether 400 or 800, the amount of data stored on a single tape is now astounding. Furthermore, I've found in our own lab that the LTO2 drive backs up routinely anywhere between 300MB/minute to 2GB/minute. The speed is directly related to whether the backup is a standard file-by-file network backup or a higher speed image backup. For those who don't know, image-based backups are the absolute fastest means of backing up and restoring a partition or disk.

Just for grins, let me compare the LTO2 of today against the first 8MM device released on Wang's VS minicomputer (my market before entering Windows). When Wang initially released the WUBU (Wang Unattended Backup Unit) using an Exabyte 8200 it cost about $20,000 for an 8MM tape, holding a little over 2GB, with a backup rate of about 400-600MB per hour. Fast-forward to today and compare that Stone Age device to a hot Super DLT or LTO2 drive that easily backs up at rates of 400-600MB per minute--and at a fraction of the cost!

For smaller users, the name of the game is still 4MM DDS-5 drives with 36GB native capacity. Such drives offer capacity, speed, and economy, to thousands of users of small to medium size networks. 4MM based autoloaders offer even greater economy of scale. Today's state of the art drives are so fast that keeping them streaming at a high rate of speed can be difficult and requires both a fast system and efficient software.

Most organizations find this a luxury, but as a prudent investment, I always recommend buying a second tape drive. A second tape drive is inexpensive and can be used as a secondary backup unit in case the primary drive fails. It can also be used to either duplicate nightly backup tapes and/or automatically cascade full tapes (if appropriate software is purchased). Duplicating a backup tape for off-site storage is a key disaster ...