To tape or not to tape, that is the question
- — 29 July, 2009 23:53
Mention Shakespeare and everyone spouts "To be or not to be." Mention backup, and the question becomes, "To tape or not to tape?" Is tape dead, or do tape-based backup systems still have a place in the modern small business?
Tape was once the only option because hard disks were incredibly expensive. And since old habits die hard, many believe tape is the default standard for backup even today.
Alas, poor Yorick, I knew tape, but tape dwindles in usefulness today, close to useless in the modern small business. Just as VHS tapes gave way to DVDs, tape backups are giving way to hard disk and Internet-based backup. Nearly unlimited disk storage space has changed the backup dynamic in ways tape can't match.
Let's take a look at how disk and online backups protect your data more completely than tape systems. Then, for those who still watch movies on VHS and believe tape is the only "real" backup method, let's look at ways to keep tape systems alive just a little longer.
For all practical purposes, hard disks, local or online, provide an infinite pool of data storage space. For local storage, 1TB hard disks (1,000 gigabytes) can be found for around $US100. Add a few to a backup server or network attached storage device, and you have years of backup space for the typical small business.
There are many ways to backup files from individual computers and servers, but most backup systems make a full backup then track the changes. If you select your My Documents folder for backup, the backup software will make a copy of all those files. When you change a file inside that folder only the sections of the file that are changed are moved to the backup system. When you need to restore a file the backup software merges the original file with the changes and sends you the latest version of the file.
Tape backup systems spread the original and incremental changes across multiple tapes, at least when you start protecting a larger amount of data than you can store on one tape. The software tracks which tapes the changed bits are on, but chasing those tapes down and getting the bits put together in the right order can be tricky. And the older a tape is, the less reliable the restoration process.
With an unlimited amount of disk storage, you bypass the scavenger hunt for the right tapes in the right order. The backup software places the original file and the incremental changes in the same backup storage pool, so all the bits are in the same place, even if they're not on the same physical hard disk. Restorations go much faster and are much more reliable. This applies whether the backup storage space lives inhouse on your network, or at a backup service provider somewhere on the Internet.
If you remember my New Year's column Backup, Backup, Backup, you read about my Pirate Backup System. Part of the system is redundancy, meaning copies of your data files are stored separately from the data files themselves. Tapeheads are now jumping up and down proclaiming tape provides the easiest off-site storage options.
They used to be correct, but no longer. Back when an 8GB backup tape could hold a copy of all the files in a small business, carrying such a tape offsite provided redundancy. That's if the tape was reliable (a coin flip with some systems), if the tape was stored properly (leaving it in the car in a Texas summer guaranteed disaster) and if the tape could be found quickly when needed. If your data backup set sprawls over more than one tape, the odds of a successful recovery from tapes left at your mother's house a few weeks ago drop even more. (Yes, people have told me they use their mother's house for offsite backup. I'm sure Mom is happy to see you, but visit for more than data backup, OK?)
Offsite backup now means across the Internet backup. If you have two offices, you can copy files from Office A to Office B and vice versa. Your Internet service provider or reseller may offer an online backup service, so ask them.
Money, always an issue, means even more today. Online storage costs range from $US2 per gigabyte stored per month down to a dime or two per gigabyte per month. One system I'm about to test, SpiderOak, offers 100GB of storage for $US10 per month, or $US100 per year if paid upfront.
Tapeheads do have a point, however, that tape remains the least expensive long term backup storage media available today. Even a dime per gigabyte per month adds up, while 72GBs on a $AU20 tape remains at the same price year after year.
Decent tape drives can now be had for around $US700 and up. One of the options when customizing a Dell PowerEdge T100 server, built for very small businesses, is a PowerVault T100 DAT72 tape drive for $US1025.20 (tapes are $US24.20).
If you are still using tapes for backup, at least follow some simple rules to minimize failure. First, verify your backups. This means restore some files from a tape now and then to make sure you're getting a good backup and the tape is usable. Does that seem silly, since the software almost certainly said the backup was successful? Reusing the same tape too often will wear out the magnetic coating on the tape, and your backup will report good yet your restore will fail.
For that reason, check the expiration date on your tape media. The manufacturer will say tapes can be reused X times. If you use them X+n times, you will be sad. Rotate your tapes, and clean the tape heads as recommended by the drive manufacturer as well.
If you can't replace your tape backup system today, start saving money and keep your fingers crossed. Move to a disk based backup system locally for speed and convenience, and add an offsite component for redundancy. After all, the data you save will be your own.