There isn't a lot of detail in the thread, but things to consider might be:-
- If you have a database, is it possible that there is a major transaction rollback being done?
- Do any of you shutdown scripts have waits in them?
- NFS (as already mentioned)
- Is there some sort of notification you are trying to do and the target server is down? Perhaps a closing down report to ensure all transactions are centrally held etc.
- Has someone introduced a backup into the wrong place, so it runs at shutdown?
- Has someone created a shutdown script that actually does a startup by mistake? (i.e. never it checks $1 for start or stop, it just starts)
- Is there an AV scan being triggered in the shutdown?
- Do you run an fsck during shutdown?
- Do you try to sync the clock during shutdown?
- Is this a High Availability node, or worse an HA node where the other node(s) are all off?
There are lots of other possibles too, I'm sure. What more can you tell us about it?
Kind regards,
Robin