The Limits to Internet Backup in Australia

By June 14, 2012Backup, Business, Servers

Most businesses want two backups for their data: an onsite system and an offsite system. (It’s worth pointing out that this point that RAID is not backup!) One convenient way of doing offsite backups is over the internet. Data can be backed up from one branch office to another, or into a data center, or your IT services provider might provide a backup server at their premises. We’ve set up all three of these types of offsite backup for clients multiple times over the years.

Off-site backup can only works in practice if you have a differential backup system. This means instead of a whole copy of your data set being copied remotely, only the difference between today and yesterday is. This is usually, but not always (see below), a small fraction of your data set.

On average, a corporate ADSL connection could theoretically cope with about 300GB a month of off-site backup. Theoretically. The obvious problems are surmountable – that your ISP doesn’t give you your full bandwidth (change ISPs) or that your quota isn’t high enough (increase it). The less obvious problem is that relying on differentials is only something that works most of the time, not all of it. So what happens when you upload a DVD to your server, or you sort a whole bunch of files into different folders, or you simply have lots of data changing regularly? Your off-site backup system starts to play catch-up. It could be months before it gets back keeping your stuff in sync. It’s trivially easy to get to the point where the estimated time of being up to speed is ‘never’. And who is monitoring all this whilst it’s happening?

Note that even backing up essential files on a single computer daily would overpower any (non-NBN) consumer-grade internet connection in this country if you didn’t use differentials. Differential backup is more complicated to set up (CoreServer does it out of the box), so off-site backup is either skipped (which might not be within your acceptable risk tolerances) or done poorly with a system that isn’t designed properly, tested or monitored. In short, off-site backup is technically complex and requires careful planning and a frank discussion about risks.

As a result of all these limits and complexity, it’s not actually possible to say you’ll be OK with only “x” GB of data. In fact, the only number you can truly be safe with is an amount you know you can back up, in full, every day if you had to. On a typical ADSL connection with a more expensive plan, this means between 3GB and 20GB of total data storage, the latter only if you have a fantastic internet connection right next to a telephone exchange with ADSL2+. As you can see, online backup is no panacea.

There are many online backup solutions out there and you may be tempted to try them. But most of them are designed for radically different markets – e.g. much of the USA, Japan or south-east Asia where bandwidth is much greater. In Australia, the limit is related to ADSL in Australia and its costs. Cable is no better (for similar, but different reasons). You may have noticed that upload is much slower than download for ADSL connections. That’s what the “A” in “ADSL” stands for – asynchronous – not the same speed. Standard ADSL uploads top out at about 1MBit/sec, which equates roughly to 300GB a month, assuming you get the full speed all the time, and your backup demands are smooth (which they won’t be). ADSL2+ tops out at around 2Mbit/sec. We see many clients with ADSL upload speeds well under 512kb/sec. You can check this yourself at SpeedTest to see how your connection fares (make sure you shut off anything else using the internet at the time to get a fair reading). Once you move beyond standard ADSL connections, prices for high-upload services move quickly toward the stratosphere. (A comparison from Whirlpool is here.). This is true corporate internet. We can help you attain this, but most of our smaller and some of our larger clients are shocked at the cost, particularly if they’re just looking for backup. This is where we’ve implemented a couple of cheeky solutions for people in the past:

  • Using point-to-point wireless between nearby offices to provide most (but not all) of the benefits of off-site backup cheaply
  • Swapping off-site backup storage (with encryption) with nearby offices
  • Doing manual once-off data “seeding” then relying on online backup for reliably small differentials

If you’re not willing to spend huge amounts of money on bandwidth, but still need offsite backup, the most cost-effective solutions are disk-based backups or a semi-automated hybrid of internet and disk-based backups. As the NBN expands, this will also bring down the cost of doing large backups over the internet. We have a bunch of solutions up our sleeve here that are not quite ready for prime time, but stay tuned or contact us to find out more.

N.B. This post did not explore non-online forms off off-site backup. In short, these are not a panacea and require considerably more manual effort to verify they actually work. That, however, is the subject of another post.