Setting up a new backup scheme

I'm in the process of designing my first ever backup scheme. I'm completely new to managing data backup, and there are some concepts that I don't totally understand. Here's what I've got so far, and what equipment I'll be using.

There are only three servers that I will be backing up, total data is approx 200Gb. I will be doing weekly full backups on Saturdays, followed by differential backups Mon thru Fri nights. There will also be an end of month full backup that will be stored off site for DR purposes.

Equipment being used: -8 slot tape backup drive -LTO2 tapes -Backup Exec 12.5 with Exchange and SQL Agents

I will be using two sets of tapes, the first for Week 1, and then another for Week 2, which will be alternated back and forth every other week.

So my question is this, how many tapes should I be using in each set? Do I have to use eight since the backup drive accepts up to eight tapes? Will it be thrown off if I put less in?

Secondly, since the diff backups each weeknight will probably only be about 5Gb or so at most, do I need to put in five LTO2 tapes (which hold up to 400Gb) into the media pool, one tape for each night? Or is one sufficient, since it could theoretically hold many weeks worth of diffs?

What I don't understand is if BE selects a new tape for each day, or if it will just continue to append to the same tape until it's full and then roll over to the next one.

Perhaps the easier question to ask, is, if you had the backup equipment and servers to backup listed above, what would your backup design be?

Many thanks....

Solution 1:

I would highly recommend the book "Backup & Recovery" (O'Reilly Book) by W. Curtis Preston

http://oreilly.com/catalog/9780596102463/

Asking how to do your backup plan is kinda like asking 10 grandmothers how to make the best chicken noodle soup. You'll get 10 different answers but all of them will agree on the basic ingredients.

In my opinion, Backup & Recovery does a pretty good job of talking about the strengths and weaknesses of different options you may (or may not) choose to implement.

So, that's where I'd start first.

Solution 2:

It's been a while since I set this up, and I'm at home so I'm going from memory.

In our case, we have an LTO-3 drive, a full backup fits on two tapes and all the diffs for a week fit on one. So every week, we have a set of tapes consisting of the two tapes for the full and a third tape for the following 5 diffs. We keep these sets for 5 weeks, we have one set offsite and 4 onsite.

We set up a media pool for the full backups with the overwrite time set to 5 weeks so that the tapes can't be re-used before that and set it to not be appendable so the next time you use a tape it starts at the beginning.

For the diffs, the media pool was set to 1 week, because after that we wouldn't really care about what was on the diffs and if we needed to we could grab a "wrong" diff tape. In practice, as I said, we always keep the set of tapes for the week together. But when we first got the LTO-3, the tapes were $50 and we were thinking we'd save money by only having a couple diff tapes and re-using them.

(I said "was" for the diff media pool because we actually stopped doing the diffs to tape and we now do a similar disk-disk-tape scheme: full backup to disk and then copy that off to tape, then the diffs are only to disk.)

To answer your specific question, when you set up the backups, you tell it which media pool to get a tape from and it'll grab the first one that's usable - that's allowed to be written to.

You said LTO-2 and 200GB, so a full should fit on a couple of your tapes, 3 at the very worst. So you could have 6 tapes for fulls and 2 for diffs in the loader at once, then every week you have to pull out one set of fulls and put in another one. If your backups fit on 2 tapes, you could have 3 sets of fulls and you only have to swap every 2 weeks.