Can we stick the fork in tape backup yet? After another exhaustive disaster recovery drill at a client where everything that could go wrong did (good thing it was a drill), I’ve been racking my brain trying to think of any good reason to keep tape backup as a method of data backup. It used to be a no-brainer, a foregone conclusion, because disk was so expensive and tape was just how everyone did it. However, as disk space has continued to drop and new software and network and USB based-solutions have come out, it's getting harder and harder to figure out why many companies are still using the same technology to back up their critical data that I used to listen to music in my '87 Nissan tape deck (or my 70s era 8-track if we're talking multi-track). The tape apologists (mostly the tape drive and media manufacturers) will claim the following benefits to tape-based backup:
- Inexpensive (on a per MB basis)
- Unlimited media size (via tape loaders, etc.)
- Portable and compact (for removal to offsite storage)
- Easier to maintain a history and rotation of backup sets
However, many of these arguments no longer differentiate it from disk to disk based backups and one of them is actually a downside now. With terabyte drive arrays well under $1,000 now, the cost per drive solutions have spanned the tape price gap, depending on whose technology or numbers you use. The very high capacity tape solutions beat this but not by much and the gap is narrowing every day. And those systems are very expensive, wanting hundreds of terabytes to justify the installation and management software. The unlimited backup size is a red herring. Just about any backup technology can be unlimited if you are willing to invest in the tape loaders arrays or other library devices. As far as being portable, of course there are USB drive solutions that are easily movable and quite small (you can get 1TB in a 2.5 sized enclosure). However, in this security conscious age, being portable and compact isn’t necessarily a plus due to theft concerns. Witness the number of data loss incidents involving backup tape media.
And how about the downsides. Tapes are software and hardware dependent. This means you have to load the software you used to create the tape media. You also have to have the appropriate tape drive installed. This is especially onerous when you are dealing with backup DR sites and rebuilding configurations from scratch. With drives you simply plug them in to the bus or via USB. They are instantly recognized as a drive letter you can access via your operating system (funky drivers notwithstanding, but that is what the Internet is for). Tapes are also relatively more fragile than their disk-based counterparts. The tapes can jam, get torn, overheated (I’ve seen this happen in cars in the hot Texas sun in transit). Yes, drives crash too but barring physical violence, their media tends to last longer. And of course there is the performance issue. Tapes are written sequentially, so if you want a specific piece of data, you have to advance the tape to that point. The seek times on even the slowest disks will easily beat any tape drive. This really comes into account when you are backing up or restoring large amounts of data. Some companies are literally running into issues of their tape-based backups now starting to take longer than the overnights allotted for them. Finally and most importantly, most IT professionals hate dealing with tapes drives. We’d much rather be able to use drive technology, which is something we use on a daily basis.
Most contemporary backup software now includes support for disk to disk backups, including USB, SAN, and other external or network configurations. There are also some innovative software solutions such as Symantec’s System Recovery Software, which allows easy restores even on dissimilar hardware or virtual environments.
So, where there is a large investment in legacy tape systems or in very large data backup requirements where the cost of high capacity tape systems can be recouped, tapes may still make sense. For the rest of us, it's time to throw off your tape shackles and join the 21st century! There may be some applications or considerations I haven’t thought of so please feel free to let me know your opinion. But for now, Viva le Disk!
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