Tape Backup Vs Disk Backup

This debate has been going around for years, and it’s time that we once again evaluate the options wisely.

Tape Backup

We’ve all seen these dreaded tapes, and for those who have had the joy of working with Backup Exec, you know that that can be a full time job.

Data Transfer: Tape backup for well configured Situations copy in at 2,000MB/MINUTE, relatively slow, given network latency, Disk Backup can copy up to 1000MB/SECOND, so as you can see disk backup is significantly faster in this area

Restores: Let’s face it, The restores take FOREVER from tapes, unless you have a small text file, but if you have ever had to deal with the tragedy of restoring a large amount of files (such as a NAS/SAN, you will wish you would have went with the other guys) Disk restores, are much faster, and can be quickly accessed.

Portability: Tapes have this category, most tapes are much more portable than a physical backup server, HOWEVER, if you have multiple locations, and multiple backup servers, you can actually setup so the two devices sync, and then do incremental transfers, making quite the Amazing Disaster Recovery Plan, that’s another topic all together.

Ease of Use: Most disk Backup solutions are easy to use, and provide a web access portal, so you can monitor you backups anywhere, without having to VPN, and do all these other workarounds.  Although tape backup solutions such as Backup Exec are easy to use, you cannot beat not having to login with a remote session, open the application, expand all the boxes, etc, it’s a real time saver.

Restore: Let’s face it, when disaster strikes, the backup part is no big deal, it’s actually the restore that’s the big dog in all of this.  Well when you are recovering from tape, you may as well bring your sleeping bag to the office. As we all know there are 2 main common restore scenarios:

1) User deleted a single file on accident

2) system is down and cannot be repaired – have to restore from backup

with a single file, it’s pretty quick to pull that over any media, disk or tape, however what if you have to restore a whole system? what if that system isn’t small, but it’s Exchange, or SQL? How then do you feel about your tape restore? not as good as your disk restore. In the past i have had to restore a 500GB exchange server, this took only a few hours, we predicted would have taken 5 hours longer on tape (that’s how much time we had left over)

but anyways, if you had to restore a system-state, in production machine, Backup to disk is going to be without your best option, and you will loose no sleep over it.  The quicker the restore, the better.

Failure Rates: Tape failure rates are atrocious. Microsoft will tell you straight out that 40% of restores from tapes fail. This is a chance that i would never take. That’s a 40% chance of loosing your job if you are the backup admin, and something goes south. Disk failure rates, although are increasingly high, you can still restore from a backup server that has a raid 5 with one disk failed, if you have a bad tape, and it’s the only one you have, your screwed. Been there, done that, the LAST thing you want to do is tell your boss that the server can’t boot, and you tried all the backup tapes, and it looks like they are all bad, and there’s nothing you can do, this is the worst feeling you could ever feel.

Additionally tapes get stretched, and have a relatively short lifetime and need to be constantly replaced, in the long term end up costing the same amount if you are buying new tapes every couple of months.

Advanced Restore Functions: Tape takes this one, if you wanted to restore a table in SQL, or an email in Exchange, tape backups have much more granular restoring technology, because they really dig in deep to byte-level. With Backup to disk, usually your option is either restore to yesterday, or bring up a DEV system, restore the live database to there, pull out the differences, and then restore. Backup to Disk only Backs up the “databases” and not the individual contents, so you are at a bit of a disadvantage if you want to restore one minor detail in a massive database.

Deduplication: Disk backup does not seem to have a lot of duplication built in, it takes a “system state” snapshot, and then says good enough. Backup to tape allow duplication to fit the most amount onto a single disk. This used to be a really big deal in the Olden days due to pricing of extra disks. Now you can get a 2TB hard drive for $100 or so, draw your own conclusions on this one.

Stress: Backup to disk either it works, or it doesn’t, there isn’t all these variables that could make it swing one way or another. You literally just set it, and forget it, just make sure every once in a while that the backups are running successfully. Anyone who has worked with tape backup will tell you that it’s a a full time job, more if you don’t pay attention.

Weigh your options, and draw your own conclusions, if you could not tell, we are very Pro-Disk backup, and have been running it for about 5 years without any problems.