How to handle server crash without loosing SEO results.?

[Dinsurf]

We have an eCommerce site having more than 2000+ product pages indexed on Google. All product page URLs are done thru mod_rewriter. Recently our server crashed and all domains & sub domains we had were pointed to the back up server by changing the IP ("A" record). Same mod-rewriter URLs were also done there again in the back up server too.

However, very next day itself, the number of indexed pages drastically dropped to 100+ and for cretain sub domains started appearing supplemental results. Even after 3 weeks, Google doesn't seem to pick these pages again.

Pls explain how & why this happened..?
Does Google penalise the domains & sub domains for not having them live when they crawl the sites..?
How can we get back to the former position..?
Still we are running on the back up server..? Should we go back to the old server where we were..?
How can we prevent this happening again..?

[lammert]

Is the backup server in the same IP range? One possibility might be that the backup server uses an IP address which is flagged by Google to be in a bad neighbourhood.

Does Google visit the backup server at all? You can see this in the server log files. I have had several IP changes (all planned, not because of a crash) and my experience is that Google starts crawling the new server at the same speed once it knows it's IP address, mostly after a few hours to one day.

What was the TTL setting of your A record in the DNS server? If you have a TTL of one week, this may cause Google and others to realize only after seven days that the content has moved to a new location.

Was the original server down (physically not connected to the internet), or was the server up and served a different page, for example a page "We are out of service now, come back soon". If the latter was the case, Google may have indexed several copies of this same error page when visiting your site generating many duplicates in its index. This can cause duplicate content problems.

[Dinsurf]

"Is the backup server in the same IP range?"
Yes both servers are in the same IP range........

"Does Google visit the backup server at all?"
Yes.. Google does

"What was the TTL setting of your A record in the DNS server?"
5 mnts

"Was the original server down?"
Yes..The original server was down

[lammert]

Looking at your answers, everything seems OK: none of te possible problems that can cause Google to drop your pages after the transition to the new server.