backup without any downtime
I need to backup entrie linux system without any downtime. Now I using dd utility to do it. I halt my system, then boot gentoo-livecd, mount USB storage and make image of my system partition. Then I compare md5sum of partition and it's image, disconnect backup storage and reboot to main system. In result I have about 10-20 minutes of downtime.
It's impossibe(or at least dangerous) to make image of system partition using dd from mounted system partition, because OS time-to-time writes to logs and so on, in result we have unmatched checksums, and filesystem in image may be corrupted. It's also dangerous to do backup with cp utility, because we do not need to copy files such devices and socket files and proc filesystem, and we unable to copy files locked by other applications.
I looking for a way to make fast restorable image of OS without any downtime, may bе LVM helps me to do it?