On Tue, 20 Jul 2004, Christopher Curtis wrote:
Actually, in practice, you'll probably find that most of the time it "just works". However, if you have LVM installed, you could make a snapshot of the image before you udpcast it. Most of the data that's not written to disk is "inoccuous" stuff such as logfiles. However, I wouldn't try this to make a copy of a running database, for instance.
Yes, this is what I am assuming. If the person states that the system must be live, it must be a production system of some type, providing an essential service that is accessed at all times of the day. There is a good possibility of files being in a state of being half written, and so on. It won't even simulate a power loss, because a low level copy of the entire drive will capture parts of the drive at a different time. In the case of something like a database, there are several files in use, and some of them may be large. It might even take a few seconds to minutes to capture a single file on the low level dump, and during that time the file has been updated in several different parts at different times. It would lead to a file of garbage and thus a corrupted database. A database is a easy example to understand, but the same could be true of any file that is being written on the system, including the filesystem table! Unless you are just fooling around, don't do it! --Donald Teed