Effect of Permanent Redirection for SE's

Does having many permanent redirections harm?

[silverbytes]

I saw some 404 in my logs of pages that are in other servers hosted since 2 years ago. In the begining those pages were on my site but, 2 years ago moved those to another domain. So crawlers come and look for my old document that is not there anymore, and keep doing so.

I put some permanent redirections from my actual site to my other domain where that document is.

Does that affect in any way?
What if if redirect that page not found to another page with no relationship puting a permanent redirection?

The page is from a client I don't have anymore so instead of mantaining a page in other site and put a redirection I prefer to send the redirection to a category on my other domain where ppl may find something similar.

Is that practice safe?
How do I get rid of spiders asking for old docs?

[troels nybo nielsen]

If spiders get 404s because they look for pages that do not exist it will be quite alright with search engines to create redirects to whatever other page you may want to. You can do that either in a .htaccess file or by actually creating those missing pages and making them into meta redirects.

[silverbytes]

Something to do to tell the spider to forget about that page?

[troels nybo nielsen]

With Google I suggest that you visit this page: [google.com...] . Don't know about the other search engines.