Planning for Disaster

Well, remember that Linode does not make any backups of your stuff.

@Bithead:

Hi –

First off, kadoos to Linode! I've been using my linode hosting virtual

web hosts and handling e-mail for over a month now. It's the best thing

that ever happened to me. Where have you been all these years? :)

Now that I'm up and running I'd like to start thinking about what kind of

disasters can happen and what would be the best protection to be

implemented. I've been thinking about a 2nd (backup) system (possibly

even a 2nd linode) which could take over in the event of any disaster.

However, before I hop on my horse and ride off in all directions, I thought

I would post this message to inquire as to what others think the potential

dangers are and how they are addressing those concerns.

I'd be in heaven if I could go on a 2-week vacation and know that

things would click along during that period.

Thanks for any input.

… doug

Automatic failover would be quite difficult to implement on any system, as far as I know. If you were to use two Linodes for this purpose, you'd have to ensure that they were in different data centers (otherwise what is the point if the data center could blow up and destroy both Linodes at the same time?). Then you'd have to have some way for DNS to automatically update to point your web server, mail server, and other services to the backup Linode should the original Linode fail.

I am sure that there would be ways to do this but I suspect that they would be so costly, so difficult to implement, and so error prone (and so difficult to prove to be effective before-the-fact), that it would not be worth it.

Backups, on the other hand, could be quite valuable. You could use two Linodes for this purpose but once again, make sure that they are in two different data centers if you do. I personally do a backup every night of my Linode to my home system's Linux firewall/router, and vice-versa. This way if either dies I can reproduce the other, although I suspect it would be less than pleasant to have to replace an entire system should the other in fact fail.

I think you can get reasonable peace of mind from knowing that the data centers that Linodes are in are very well protected from power failures/natural disasters/crimes/etc, and so the weakest link by far is your individual Linode. If you back that up regularly, then your window of exposure to data failure is pretty small. For me it is 1 day. Of course, if Linode.com went away tomorrow it would take me several days to sign up for a new hosting provider and copy all of my backed-up-data over. But I find that an acceptable level of risk for the amount of effort I have to put into making sure that my Linode stays well-backed-up (which currently amounts to about 10 seconds a day reading the email that my backup process sends to me to make sure that it all went OK).

If you come up with a good solution to your problem, please post it here, I'm sure others in addition to myself would love to hear about it …

You may want to look into a feature that Dynamic DNS offers: Offline URL. I haven't tried it myself, but I expect to soon. Basically you could have a "backup" Linode that syncs to the main one nightly, and have it set up to answer queries when the main one is out.

Of course, if what you're serving up is static, then you can just set up both hosts in the DNS for some load-balancing. If it's dynamic, that's tougher since both would require access to the same database. Although you may want to look into mySQL (or whatever) master/slave replication relationships.