Lukas Beeler's IT Blog

Backups are nothing new – everyone, even if they’re not affiliated with IT directly knows this word.

Unfortunately, the term “Backup” doesn’t actually describe any concrete measure. One of the important things is to know for sure what you want to protect yourself against with a backup – this will heavily influence your choice of available solutions.

So, what are possible things that could happen to or in your business, which would require a restore?

• Accidental deletion
• Accidental modification
• Disk crash
• Hardware crash
• Software crash
• Malicious deletion
• Malicious modification
• Environmental disaster, destroying the whole building

I’ve ordered the items according to the numbers i’ve seen them happening. Note that this might be different for bigger businesses.

So how do we protect our business against accidental deletion or accidental modification? When you’re using Windows, the easiest way to guard against this is a feature called Shadow Copies. Shadow copies are nothing more than volume snapshots with a nice GUI around, and a way to access them over the network. Once you have this implemented, you don’t want to miss it. It allows users to recover deleted files on their own, quickly. It also allows you to recover modified files. You can set the timing for creation through the usual windows scheduler. Shadow copies just use disk space – implement them now if you haven’t already.

The next step on the list is a disk crash. This one is easy – just read this post about hardware redundancy. However, what to do if two disks fail at once, or the RAID controller?

Please note that neither Shadow copies or RAID replace a backup – but they are part of your backup strategy.

Complete hardware crashes happen seldom. And if they do, they usually don’t destroy your data. The best safeguard against hardware crashes is a maintenance contract or service pack on the machines – no matter what is broken or missing, someone will come over and replace the part. No backup necessary.

The worst that could possible happen is a software crash – a bug in the filesystem driver destroying all your data, or leaving your SQL database in limbo. You will need a complete backup for that, and this is where it starts to get expensive. You can achieve complete backups to disk (usually to a SAN or NAS), which is a nice for a bare metal restore, but has other problems.

What about malicious deletion, malicious modification? They could have happened months ago, until somebody else works on the data, and notices the problem. This is why you need backups that go back for quite some amount of time. You can buy a lot of disk space for your SAN or NAS, but that would get expensive.

And what about a environmental disaster, destroying the company building and everything that was in it? You will need some way to keep your data off site for that. You can move hard disks off site, but they are quite fragile. Replicating the data off site could be a solution, but has other problems.

The easiest way to get done with the latter three issues are tape backups – i’ve seen many people laugh at tape backups, but they are a great solution to many problems. LTO3 tape drives are fast, really fast. They also pack quite an amount of storage, with 400GB physical and 800GB theoretical maximum. you can get 500-650GB on them without problems. This allows you to do daily, full saves, and storing some of these full saves at an off site location. If you need more than one tape to save all your data, you can use tape changers. They were expensive once, but for now they come in at about 8000 CHF.

Tape drives are also an easy concept to explain to a non-IT person, because it involves physical objects.

You could also implement a multi-tiered infrastructure, backing up to disk first, and to tape later, which is what many enterprises do. But usually the complexity involved in such a setup by far outweighs it’s advantages.