Re: RE: RE: FN-FORUM: Is it possible to host a website on two servers as a backup?

date posted 25th January 2007 13:42

On Thu, Jan 25, 2007 at 02:17:43PM -0000, [EMAIL REMOVED] wrote:
>
> hardware failover? yeah I'll admit thats not cheap! although if worst case happened and your host's building imploded, you'd be a bit stuffed ;)
>
> FWIW we tested the DNS failover by getting the system to monitor a url on FH then deleting the page, it took 30 seconds to switch to the US server but about 3mins to switch back once we re-uploaded the page on FH. Not bad I dont think.

The point is that you have a trade off: failover time vs cost.
In practice most sites do not need 100% uptime (ie instant failover), this is *very* expensive.
If you can afford a few minutes then your costs can be quite modest.

Static sites are not a problem, dynamic ones: you need to synchronise the databases - here you need
to decide: must you *never* loose anything or is it OK to occasionally drop a transaction (and manually
recover/... later; assuming that the failed machine is not a total loss due to fire or something).

Summary: How safe vs what it is worth

--
Alain Williams
Linux Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256 http://www.phcomp.co.uk/
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