Originally posted by KenEwald
A cold backup would give a solid point at which to delete archived logs.

For an informix guy that's a good, simple, straightforward suggestion.

It's simple and it'll work.
Please! Don't give the informix_guy the wrong impresson that cold backup would be in any way more solid point to delete arch logs than a hot backup would. That would make him to be one more of the loosers that belive in urban legend that cold backup is anything safer (or simplier) than the hot backup

Any full backup (either hot or cold) is the same in respect of which old arch logs you still need.

I also don't understand the meaning of "[Cold backup (and recovery from it)] is simple and it'll work". In what part is it simplier than hot backup and in which case hot backup would not work?

So informix_guy, here is the consise answer to your question:

When performing media recovery, you'll never need any arch log that was created before your backup (either hot or cold), from which you restored the database, was taken. So you'll have to decide which backup is the earliest possible one that you'll ever need for recovery, and you can safely delete all arch logs that were created befor that backup started.