rebuilding master database vs reinstall instance and restore dbs

You really need to restore the old master and msdb.

Master contains all logins, linked servers and current configuration settings, for example.  So you will lose all your logins and any linked servers and adjusted (tuned) configuration settings.

Msdb contains:
    -- all job-related info (jobs, schedules, etc.)
    -- all packages (stored in SQL)
    -- all alerts and notifications
    -- backup and restore history for every db
    -- operator info (if you've added any)


It's not really that hard to restore master, but you do need to practice it before an actual disaster occurs.  After one or two recoveries, it will be fairly straightforward to you.

thanks Scott - that is not what I am after though. I forgot to say you would assume in both case reinstall instance and rebuilding master (REINSTALLMODE=AMUS) you would continue on to restore the master db. My question was what is the advantage of rebuilding the master database (which you would restore a master db afterwards - sorry I left that out) and restoring user dbs vs reinstalling the instance and restoring all the databases

D'OH, sorry, quite right.

Assuming the disk data is not damaged, you should be able to simply restore master, msdb and the user databases [you don't even need to rebuild the existing master].  That should not be any issue *for SQL*.

However, from what I hear from our Windows and applications folks, Windows and apps, if you have installed on that box, may not handle a crash recovery as well.  So they usually insist on rebuilding from scratch for Windows recoveries.