On Thu, 2004-12-23 at 13:41 -0600, Aleksandar Milivojevic wrote: > Laurence Orchard wrote: > >>What's the recommended process to create an exact duplicate (boot sector > >>and all) of a hard drive? Is it really as simple as: > >> cat /dev/hda > /dev/hdb > > > > In answer to the question, I would partition the new drive, > > then use > > > > dd if=/dev/<old-drive> of=/dev/<new-drive> > > Which would overwrite the partition table, so why bother to partition > the drive in the first place? > ok perhaps to clarify! dd if=/dev/hda1 of=/dev/hdb1 Copy partition at a time if there is more than one. > Anyhow, using dd is better solution than using cat. One dd option to > check (which might speed up things) is bs=n. By default it is 512 (one > disk block), so dd will read 512 bytes at a time. Using bs=8192 should > make things faster (this way dd will read/write 16 disk blocks in single > system call). Just make sure size of the disk is multiple of whatever > you use for bs (otherwise you might get error on last read), and that > argument for bs is multiple of 512 bytes (disk blocks are 512 bytes long). > > I'm not sure how happy the system will be if disk geometries are not the > same (if you simply copy partition table using dd). Try something along > the lines "dd if=/dev/hda of=/dev/hdb count=1" (this will copy just the > MBR, which contains partition table), and than "fdisk /dev/hdb". See if > it will complain, and if partition sizes look right. > > If not, partition the drive manually, and use dd to copy individual > partitions instead (dd if=/dev/hda1 of=/dev/hdb1 bs=n)... > err, this is what I meant! sorry if I confused > Warning: when you copy over MBR (effectively repartitioning the disk), > the kernel will not be aware of the new partition table. This is > because kernel will read it at startup and will chache it. Quick > workaround is to do "fdisk /dev/hdb", and exit from it using "w" > command. fdisk reads partition table from the disk (not from the > kernel), and when it writes it out, it calls ioctl that instructs the > kernel to reread it. After that, you should be able to test-mount new disk. > > -- > Aleksandar Milivojevic <amilivojevic@xxxxxx> Pollard Banknote Limited > Systems Administrator 1499 Buffalo Place > Tel: (204) 474-2323 ext 276 Winnipeg, MB R3T 1L7 --
