Can dd be used on a live system?

[jemate18]

I have an FreebSD 7.1 ftp server setup... I access it via ssh on my laptop in our office.

If i'm in that system through ssh, can i use dd to back the full HD including the partition tables and all?

dd if=/dev/ad0s1 of=/usr/home/yyy/backup

then how do i get that backup to be stored in my laptop? Do i have to log off via ssh and use scp for it?

Other thing.... if i execute dd with someone transacting/downloading with FTP on that server.. Will dd fail?

Thanks

[Pushrod]

I don't see dd failing. What I do see is it potentially copying data that is not in a consistent state, making the copy partially corrupt. If you mount it read-only while you dd, you should be fine.

[graudeejs]

if you use UFS2, man dump, man restore
they cover how to back up over internet
or
http://forums.freebsd.org/showthread.php?t=185
fallow this, and when finished simply use scp to copy over net

[vermaden]

and when finished simply use scp to copy over net
You can use pipe to sent it directly without using local space:
% dump -0 -f - /home | ssh backup@server.org -c blowfish "gzip -c -9 | dd > /storage/backup/home.dump.gz"