What could be some of the primary repercussions from the site being down so long, in regards to search engine traffic?

I don't know that, but I do know that downtime of a week for any even remotely serious site is not only unacceptably long, but likely unneccessary, too.

Is there anything I can do to minimize permanant traffic loss?

Fire your IT team and get a new one! A week is outrageous.

What could be some of the primary repercussions from the site being down so long, in regards to search engine traffic?

Depending on the spidering frequency of your site, they could be rather severe.

I don't recall anyone specifying an exact time period of when a search engine will eventually purge a 404.

Those pages that have external links to them will most likely survive. The ones that don't have external links to them may be affected.

One week of downtime is totally unacceptable. One day is unacceptable. One hour is unacceptable. And since I'm somewhat strict, one minute is really unacceptable for me. ;)

For any downtime, you should always ensure that your server is giving the correct response (unless it is giving no response at all). You have two options: Error 503: Service Unavailable is the best option, followed by 500 Server Error if for some reason you can't generate a 503.

However, one week is unacceptable, even with a 503 in place. A day or two with a 503 will affect you short-term, but the site will come quickly back, at least in my experience.

You will have problems if the site serves a 404 Not Found or (shudder) 200 OK but with an error message rather than the intended content. It is difficult to guess the extent of the problems you might experience, but indexing issues may continue for several months. Even a server timeout is much better (or less bad) than a 404 or 200 with no content.

Just for a reference point, a friend's site was off-line for a total of ten days because first he forgot to renew the domain, and then there was some third-party DNS service which for unknown reasons was pointing the domain to the wrong IP address. The DNS problem was corrected, but it took a week in addition to the three days that the domain had been expired.

Results are that the site has disappeared completely from Yahoo and MSN, has only a few pages in Google's index that don't rank for any search terms, and is (apparently) unaffected in Ask. The site was restored over two weeks ago, so this was serious "damage" and is taking far longer to recover than expected, despite previously-excellent search results (it is a unique, content-rich site in a fairly-small niche).

So, read the opinions above seriously, as this could have easily put my friend out of business if he did not have other marketing channels.

Copy your site to a development server, and do all "maintenance" on that server. Once the work has been finished, switch the DNS to the development server. Leave both servers active during the DNS propagation time.

Alternately, copy the live site to a subdomain on the same server, do the work on the subdomain, and then switch the sites by changing the server config once the work is completed.

Doing it this way, your downtime is essentially zero.

Jim

Just to satisfy our curiosity, what on Earth requires your site to be down for such an extended period of time?! As has been previously mentioned, there is no reasonable excuse (that we know of) for such a long downtime. I second the motion to sack the entire IT staff if that's the best they can do.

LOL! I would have to agree with you there. It's totally crazy.

I work in a corporate environment. So that means everything moves really slow and they don't take well to change. Evidently this has been going on for years. They take the site down once a year for a week to do upgrades and maintenance.

Don't say it. I did ask. "Can we host the site somewhere else?". Well, the only problem is that I seem to be the only person in this company that can foresee this being a real issue. Plus the fact the site has over 100,000 pages. It seems too late to stop this crazy thing.

Well, the only problem is that I seem to be the only person in this company that can foresee this being a real issue.

Now is the time to implement a good CYA policy and put your concerns in writing. The annual 1-week shutdown debacle could be why you're only getting 25% of your traffic from SEs.

It may be too late to avoid this year's debacle. But do some good monitoring of traffic and rankings before/after the downtime. Use any major differences as ammunition well in advance of next year's planned debacle.

It doesn't matter if you have thousands of pages or millions pf pages. It is not difficult to setup a backup server that redirects all pages to a "temporarily down" site. My first guess would be that a 302 redirect would be the most SE-friendly redirect to use. Anyone else with more experience have other suggestions?

So that means everything moves really slow and they don't take well to change.

This is why I left my previous job, I LOVED the work but couldn't get anything done. Sure you can submit a letter. It will go into committee, and disappear. The only time anyone takes notice is when you storm into the board room with guns blazing (literally.) Even then, they will adjourn and have a meeting about the interupted meeting, which will be postponed.

Your only recourse is to take matters into your own hands. Ride the bullet. Set up hosting on some cheap server, point the IP addy of the domain to it, and set up 8 or 10 rudimentary pages from your current site on it. Point it back when your corporation gets off the gravy train. True this will also have SEO implications as well but they will be nowhere near as severe as pullng the plug for a week.

Thank you, thank you. Honestly, I don't know what I would do with you guys and gals.

LifeinAsia, I took your advice and sent an email about my concerns with the site shutdown to the appropriate channels. Thanks alot. It was on the money.