Be VERY careful with if (input file) and of (output file).

If you can attach both disks, copy directly (much quicker): sudo dd if=/dev/disk2 of=/dev/disk3 bs=64k.

Make sure the destination has enough space for the disk image, eg, equal to (or greater than) the source.

If the copy fails due to disk errors, try using the following command at step 3:ĭd if=/dev/disk2 of=/Users/mike/diskimage.img conv=noerror,syncĭd will take much longer using this option, errors are written as NUL bytes. The second dd command is almost the same, but if and of are reversed. Sudo dd of=/dev/disk2 if=/Users/mike/diskimage.img Attach and identify the destination disk ⇒Ħ. Sudo dd if=/dev/disk2 of=/Users/mike/diskimage.imgĤ. If the installation has primary and backup signalling servers, clone one at a time to avoid service interruption. Make a working copy of a Signalling Server hard disk This option can often recover a dead hard drive, or an unreadable file, but it does not repair the error. If the operation stops with an I/O error, try to salvage all readable data with conv=noerror,sync.

conv=noerror,sync tells dd to be fault-tolerant and ignore read errors (optional).

bs=n sets both input and output block size (optional, default=512 byte blocks).of= specifies output path (file, or device).if= specifies input path (file, or device).There's also a freeware version of dd for Windows available, with instructions.

How to clone a hard disk or USB stick in the terminal.ĭd (disk duplication) is a Mac OS X command-line utility which can read raw data off a disk, even if the Mac doesn't understand the filesystem.

Mac disk image command line