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sfuller
February 9th, 2009, 10:35 PM
i would like to know how to copy one hard drive to a second hard drive not just the file the whole thing so if one hard drive goes i can just boot from the second drive.
logos34
February 9th, 2009, 10:45 PM
Cloning an entire hard disk:

dd if=/dev/sda of=/dev/sdb bs=4096 conv=notrunc,noerror

/dev/sda is the source. /dev/sdb is the target. Do not reverse the intended source and target. It happens. Notrunc means 'do not truncate the output file'. Noerror means to keep going if there is an error. Normally dd stops at any error.

http://www.linuxquestions.org/questions/linux-newbie-8/learn-the-dd-command-362506/


Just make sure to change the UUID of the partitions on the cloned drive so grub doesn't get confused by two / with same #

sudo tune2fs -U random /dev/sdxy

(where sdaxy = the root partition on the backup drive)

then edit /boot/grub/menu.lst and /etc/fstab

do same for /swap and any other linux partitions\

sudo blkid

will list the partition uuids
HermanAB
February 9th, 2009, 10:56 PM
You can also do this over a LAN using Netcat:
http://aeronetworks.ca/netcat-howto.html

Cheers,

Herman
windependence
February 10th, 2009, 12:12 AM
Just be very careful you don't reverse the source and target as logos34 mentioned. That's why we call dd "disk destroyer". ;)

-Tim
anonymousnobody
February 11th, 2009, 08:20 AM
Just make sure to change the UUID of the partitions on the cloned drive so grub doesn't get confused by two / with same #

sudo tune2fs -U random /dev/sdxy

(where sdaxy = the root partition on the backup drive)

then edit /boot/grub/menu.lst and /etc/fstab

do same for /swap and any other linux partitions\

sudo blkid

will list the partition uuids

do the hard drives have to be exactly the same size (if they do, do they also have be the same make/model)? if not, what if the source is smaller than the target? will dd handle the size difference or do i have to repartition?
windependence
February 11th, 2009, 09:11 AM
Yes, IF you use the conv=notrunc,noerror option.

notrunc means do not truncate the output which writes zeros to the end of the drive after the data is written. noerror means what you think. dd would normally throw an error about reaching the end of the data. Basically, you're just telling it to keep going no matter what.

-Tim