amd64/112828: Complete data loss after upgrade 6.1 -> 6.2 (Amd64)

[Vladimir Jakubal]

>Number:         112828
>Category:       amd64
>Synopsis:       Complete data loss after upgrade 6.1 -> 6.2 (Amd64)
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-amd64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon May 21 06:30:06 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Vladimir Jakubal
>Release:        6.1 RELEASE Amd64
>Organization:
>Environment:
(impossible - crash!)
>Description:
After automatic binary upgrade from 6.1 Amd64 to 6.2, there was no "error" or "warning" message. I have made some few things and let the server reboot. It didn't come up anymore. Intel rack platform SH-3000, Sata Raid - mirroring.
Booting came to a point of "can't find init" and automatic rebooting (couple of times). I tried to boot from another disk, and (WOW !!!) slices WERE NOT unmounted cleanly. FSCK gave me MANY errors (though using soft updates) and most of data were not recovered using many different tools. God damned! 
We have some backups, god bless, but I would never await total distortion of all data partitions at once !
>How-To-Repeat:
Never, pleeeease!
>Fix:
Either don't use Amd64 branch or don't try to upgrade. Always make a fresh install and move configs and data! 
>Release-Note:
>Audit-Trail:
>Unformatted: