Linux Drive Clone Question

Clarifications

Linux (at least the ones I've worked with) creates a /dev/sdaX for the USB drives. Pretty much like /dev/hdaX is for your hard drives. So using dd with 'if' and/or 'of' as /dev/sdaX (where X should be replaced with the proper identifier) should work. For example:

dd if=all.img of=/dev/sda1

Would mirror the all.img file to whatever is connected on /dev/sda1 (namely your USB drive)

You can read more here:

http://wiki.mandriva.com/en/Docs/Installing_Mandriva_Linux

Thanks. I'll post back soon.

I too have recently needed to create images of new systems, I ended up using partimage from the system rescue CD (www.sysresccd.org) I did not use USB disks but created a samba share on another machine, and on a gigabit LAn it created images in 30 mins or so. The CD is worth a look for the other tools as well.

You can download and install mondo-archive this backups a complete drive to another medium cd/dvd and problably also usb-drives. Afterwords you can boot from the new image and do a mondo-restore.

is a good program I have used several times in the past. It is nice in that it can (and prefers) to send and receive images to and from a tftp server over the network. But it can also do local disk clone jobs. As for your ghost clone, I have no idea why its so slow, it should not be. I get at least 98MB/min on mine when booting off the ghost cd and cloning to a usb 2 drive. I would double check that your port is usb2, and or make a custom boot disk with the usb drivers for your machine. Ghost 2003/Corp 8 was the last good Ghost product from THEM.

Thank You all for replying. I will consider this question closed now. I have lots of things to try, but I ran into a new problem, as on 2 Linux Distros, they will not recognise the external USB drive (tried 5 drives) and Win finds them all. Some have data, some do not. The USB flash drives are all found just fine. So I need to get by this stump before I can continue with the image part.

Once again, thank you all for the help and support.

should not be needed for either a usb hard disk or a usb flash drive. I stick mine in the slot, and it loads, mounts, and puts an icon on the desktop (Ubuntu 6.10). But, it will also do this in fedora and gentoo (tested them in the past). It sounds like maybe you need to set your removable media access in the system preferences. In linux, as in windows and mac, USB just works. Linux is a little more picky about clean mount and unmount though.

But its odd that PCLinux didnt detect it right away. Its the only distro that gives me WPA and a wireless driver on my laptop right off the install. Anyway, it did seem odd to be having problems with USB disks, I have a 500GB and a 400GB that I use back and forth between Ubuntu and Windows with no issues at all.

in as root occasionaly. I use to do it all the time, but as I made some serious blunders and learned from them, I started using su and sudo more and more. I managed to override some warnings in a gentoo emerge that created a situation where the login and session deamons were "gone". I had to boot from a rescue cd and basicly rebuild the base system =\ If I had not been root, it would have been more difficult to over ridethat warning. But, as they say, the best way to learn a new town is to get lost. The best way to learn a new OS is to break it and fix it.

... that they wouldn't be strictly
consistent. While the drive clone from the
live system worked, the filesystems were
not "frozen" so data was changing on the
disk as it was being cloned.

The fact that the cloned copy worked at all
is a testament to the robustness of the
filesystems that were in use.

There is a snapshot function for doing this
properly in Device Mapper, although I have
never used it. (See the LVM HOWTO for more
information.)

Stephen

Thats some good info. I was very suprised that it worked at all, only thing I can think is that its was using a spapshot function to image the open files. Being linux, it may have used the system calls to initiate snapshot on the DD command....no idea really, but I will be looking into how to make use of the snapshots.

Don't forget that dd works by simply
copying the device (disk, partition, image
file, tape, etc.) one block at a time, and
has no concept of the filesystems or files
that reside on the device. It's just binary
data as far as dd is concerned. (It's quite
happy to let you do 'dd if=/dev/zero
of=/dev/null', which will run until you
stop it, copying never-ending zeroes into
the never-full bit-bucket! /dev/zero is
handy for wiping a disk reasonably
securely - I defy anyone to retrieve any
data afterwards without cracking open the
drive and using special equipment.)

So what it did was to copy each sector as
it went, and whatever happened to be in
that sector at the moment at which dd read
it in was what got saved in the clone. If a
file was added to a directory _after_ the
filesystem structure describing that
directory had been copied, the file would
not show up in the clone. The inode tables
would also be inconsistent with the disk
contents.

If you're feeling silly, you can even start
dd'ing then, a few minutes later, run mkfs
("format" in Windows parlance) on the drive
and dd will probably continue cloning it as
if nothing had happened. You might even be
able to mount the old filesystem in the
clone and see some of the files.

This is why you should really remount live
filesystems read-only if you're going to
image them with dd - it will ensure that
the filesystem stays consistent while it's
being cloned.

Also - *BEWARE* - the same works in
reverse: if you accidentally type something
like 'dd if=disk.img of=/dev/hda' instead
of, say, '... of=/dev/sda', you'll
overwrite your primary master IDE hard
drive, even if it's in use at the time!
(There are ways you can make this less
likely to happen, such as by using udev
rules to assign permissions for USB disks
that allow your regular user account to
access them directly instead of having to
be root. That way, you'll just get
an "access denied"-type error if you try to
overwrite your main drive.)

when I plug in a drive, it is automatically mounted. would I have to dismount it and then re-mount it as read-only?
If so, how would I add the read only part? Looking at the 'mount' command, it does not list this option.

The easiest way to remount a drive
read-only is to do:

mount -o remount,ro

where is the place where the
drive is mounted. (You can give the device
name instead of the mountpoint if you
prefer.) I don't use an automounter for
this very reason - I don't always want a
disk mounted when I attach/insert it (a
CD-RW or DVD-RW that I'm about to erase,
for example) and, if I do, I may not want
the default mount options.

If you're just going to image the drive,
you could simply unmount it from its icon
on your desktop (I'm assuming that these
fancy modern distributions all create
icons 'on the fly' for removable drives; my
homebrew system certainly did until I
disabled that feature).

I can see how DD in and of its self is a very powerful tool. There is no need for a commercial product like ghost when DD will do this for free. A good multi disk VM seems just the thing to play with this.

Once again Stephen, good info and good descriptions of what DD is doing. Thanks again.