It appeared to be working, but it didn't finish within an hour so I went to bed. I formatted the 10GB hard drive to "erase" the dvr contents, then used dd again to go back from the dmg file to the hard drive. I typed the command and 45 minutes later I had a 10GB disk image on my computer. Then I removed the drive and installed in my mac. (1GHz G4, OS 10.4)īefore I tried the bad drive (120GB), I installed a smaller working 10GB drive into my DVR and recorded a few minutes. This sounds like the right tool, because the dvr hard drive is an unkown format an unreadable file system by my mac. I would like to use this hint to attempt to get back some bad data on my dvr's hard drive. Reading may take forever as internal disk microcode will try to read every failed block numerous times. You should see some activity on that drive. In my case FW enclosure was disk1.ĭd bs=512 if=/dev/disk1 conv=noerror,sync | gzip -9 > ![]() To decide which one is it (don't you hate UNIX for its unbelievable sloppiness?) go to Disk Utility, select your disk and using contextual menu (right mouse click) get Information. ***Disk Appeared ('disk0s9',Mountpoint = '/', fsType = 'hfs', volName = 'System') (for ref here is my bootup system disk mounted, ***Disk Appeared ('disk0',Mountpoint = '', fsType = '', volName = '') ***Disk Appeared ('disk1',Mountpoint = '', fsType = '', volName = '') With my failed FW enclosed drive hooked up I got two new entries Put it back in the original machine, boot it up from external and try again. In the latter there is no way you can use this scheme in ext. Depending on the phase of the moon, the fire wire bridge chip will reported it as a unformatted drive or will refuse to work with the disk at all. Once again, that which destroys a Windows box becomes a play thing to a Mac OS X box. xls files and the lot.įinally, since your disk is actually dying, once you have your image, you can drop it to tape or something and you've not only recovered your files, you've made a viable backup as well. Once your image is mounted, it appears in your Finder, and then it's easy work to retrieve the critical files from the image - usually things like. In straight UNIX, if you try to mount a disk image, it complains that there is "no block device" and fails. who cares if it's FAT32, NTFS, whatever.ĭue to the size of the image that we were copying, we put it on a RAID array, and had to access the image over the network - it still mounted fine. As long as the damage isn't to the boot sector, though, when you double-click on it, Mac OS X mounts it without breathing hard. You have to realize that this is an exact copy of a busted drive, but the "holes" are filled with nulls. In this example, the dd output file is foo.dmg. Here's where your Mac OS X box is far and away the best thing to have. ![]() Once you've established the disk image (in this example, foo.dmg), you're almost home. One workaround is to put it on a RAID array. Since dd doesn't care about the contents of the drive, it copies every bit on the thing, so you get an image equal to the disk's capacity. Make sure that the chosen directory ( some_dir) has enough room to take the entire disk image - which will be equal to the size of the drive. The bs=512 designates block size, and the if=/dev/rXX# is the UNIX path to the actual disk device. We did it on BSD Unix, but as long as you can get the hard drive attached to your Mac, the command is the same:ĭd bs=512 if=/dev/rXX# of=/some_dir/foo.dmg conv=noerror,sync So the workaround was to designate the dd mode as noerror - which just slides over the hard stops, and to add the mode sync, which fills the image with nulls at that point. We fired up dd, and it started OK, but stopped at the same physical error location - complaining about a Hard Error. It would boot in Windows, but then it would hit one of these scratch marks and just die. We had a situation recently where a friend sent a disk to us that had hard physical errors on it. But what happens when your disk is becoming a doorstop? As long as it continues to spin, even with physical damage on the drive, dd and Mac OS X will get you out of the fire. Normally, in order to make a disk image, the disk you're copying from has to be able to spin up and talk - in other words, it's OK to make a copy if the disk is healthy. ![]() It's a great way to workaround the need for Norton Ghost. It makes a bit-by-bit copy of the drive it's copying, caring nothing about filesystem type, files, or anything else. The Unix program dd is a disk copying util that you can use at the command line in order to make a disk image.
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