cloning with DD and NC

scoob8000 · 11-11-2004, 11:12 AM

Is it safe to clone a running system over a network with DD and netcat?

The system I need to backup would be a rh9 system runing at runlevel 3, doing just about nothing.

-scoob8000

scoob8000 · 11-12-2004, 07:59 AM

Well, I tested this and it worked.

Did I get lucky, or is this safe to make a reliable backup?

-scoob8000

kees-jan · 11-12-2004, 08:25 AM

This kind of depends on how you define "safe". But, depending on the processor load

The filesystem you copy may be inconsistent
The files themselves may be in an inconsistent state (especially databases)
You may loose data
System status information (i.e. what services are running) may not be correct, and you may encounter bugs in the scripts that recover from that situation.
Possibly other mayhem

There are companies that claim they can safely backup a running system, but I still have to figure out what they mean with safe (i.e. against which of the above they protect) and how they do it.

For now, I gues you got lucky. But you did have a fair chance of being lucky, since the box was doing virtually nothing :-)

Groetjes,

Kees-Jan

scoob8000 · 11-12-2004, 11:34 AM

Basically by "safe" I meant I would wind up with a usable clone..

I would normally boot to a rescue disk, but this one problemsome system doesnt like to boot off cds, and it lacks a floppy drive.. heh

-scoob8000