Spacing out full backups

Bigger, faster, better. That’s one of the common catch-phrases of backup architecture. Backup window too small? Buy faster, and more tape drives! Or buy a VTL! Or buy backup to disk!

I’m the first to admit that sometimes the only way to solve backup window issues is to invest in additional infrastructure.

However, one thing that is frequently not considered is this: do you really need to run all your full backups on a weekend?

Most companies religiously run full backups on a weekend – regardless of the frequency (e.g., weekly or monthly), full backups for all machines will run somewhere between Friday evening and Sunday, so as to (a) maximise the size of the window for full backups and (b) minimise the impact on 9-5 Monday-Friday users.

There are of course some instances where it’s absolutely, without a measure of a doubt, completely necessary to run full backups on the weekend. However, if you’re struggling with getting the full backups for every server in your environment complete over the course of a weekend, you should ask yourself – can any machine get a full backup at another time?

I’ve seen a lot of sites save significant money on infrastructure by asking this question and realising that not all servers had to get a full backup on a weekend. For these sites, while some servers did have to continue to receive full backups on a weekend, many servers could have their full backups shifted to other days of the week. In the most extreme of circumstances, many sites have been able to spread their full backups out over every night of the week. The advantage of such a scenario is that the backup environment no longer has to be designed for extreme peaks in throughput requirements, with the nightly data distribution being far more even.

For instance, if servers in your environment have an even distribution of data, then rather than say, backing up 500 TB of data over a single weekend in full backups, why not run say, ~71TB of full backups every night? (Obviously the infrastructure requirements for such differences in full backup sizes are going to be considerably different.)

The next time you’re worried that your data is growing to the point that you can’t meet your full backup windows, stop and have a think about whether any of that load can be shifted to another day of the week. If they can, you may save your site some money.

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