What's the worst that can happen on changing servers for website?

[Corporate mafia serving since 1776]

What's the worst that can happen on changing servers for website?
What's the worst thing that can happen when I choose to change my webserver and host somewhere else.My website is a "local" website with thousands! Of folowers subscribers and newsletters etc.Lets say I have 20,000 followers maybe more and over 5 to 10 thousand newsletters.And I want to change hosting to a server.I am told if I don't transfer and save everything I will lose everything.Also my seo will be ruined and backlinks screwed up (whatever backlinks are).On the seo I could careless about seo my website is LOCAL and of course it will top rank on its own website result page in no time.And I update my data and articles weekly so I don't think I have anything to lose.Im just wondering about backlinks.I also have Facebook and twitter and youtube fan pages but that has nothing to do with anything I'm just saying
I have to add my newsletter subscribers manualy I suppose ? Lol

[Toughtub349]

If you move your website from one provider to another.. as long as they both support your software
( OS, Apache/IIS, PHP, etc.. ) .. then you just need to transfer the files in one big "get" - "Put"..
your new service provider can probably arrange the transfer for you, and let you test it.
..

while testing, the old website is still "live", and you access the new site by http:/new ip address

I highly recommend overlapping by at least a few days, so you can make sure all your stuff works with the new provider. It gives you a chance to fix anything that may need it, too.

If testing works ok, then you just need to update any files that have changed ( or not.. if not a big deal).. and have your provider change your A record ( domain name -to- ip address) with your registrar.
Again, you can do this.. or if you give the info.. you can have your provider do it for you.

If the software needs to change, then that can add a lot of problems with the functions you provide.
.. but that will happen if you change software with old provider or new provider.

The main problem from changing service providers is that you will have between 4- 24 hours of downtime. Not because anything is broken, but the DNS records propagate slowly. In order for every lookup to find your new address, it may take a day for all the DNS machines in the world to catch up with the new info. This will affect your SEO and backlinks, but only temporarily. They should be linking your domain, not your IP address.


Points:
1) You should have a backup of EVERYTHING. You should be doing this every day or every week, at least. If you ever have a problem.. nobody but you is going to care as much for your data.
It is more important now that you are even considering changing providers. It may not be professional, but it is reality.. the "old" provider isn't happy you are leaving. Make your own backups. Of course, it can't hurt to tell them.. " Hey, you guys have been pretty good for the past 2-3 years, but I have been told by friends that these other guys are great. If they aren't all I need, then I'll be back. Do you keep backups ? How long after I leave will you destroy all my old data? "

2) passwords - Admin access to your files, so you can make backups.. so your provider can transfer files.. passwords to change your Registration status.. are dangerous.
Change them and write em down someplace safe as soon as you are done with the changeover.
Your old provider ( and some employees) will have easy access to your files and can get/crack passwords.. then screw with your website. If they lose your data, or lose an old backup tape.. then anyone in possession of that can crack passwords.
Anyone who gets your domain reg password can steal your domain name.