I installed Solaris 2.5 at my SS10/51 box 30 January 1996. Patched 2.4 release had been upgraded during about two hours. I have 100MB root partition with about 75MB free.
Be careful before first rebooting your host if you are
using sendmail 8. As the configuration files are incompatible
with the Sun ones, your host may produce some rejects before
you restore a working configuration. I recommend to remove
/usr/lib/sendmail before the first reboot.
/var/sadm/system/data/upgrade_cleanup
contains a list of files which you should check manually.
fs) which
listens port 7100 by default. If you use X11 xfs
font server, comment out the fs line in
/etc/inet/inetd.conf file. Or comment out
the start of xfs (typically in your
rc.local file.
sendmail 8.7.1 compiled under 2.4
without any problems.
Note that the default path for shell has been changed. So some scripts which call binaries without precise path may runs incorrectly.