Wikipedia:Reference desk/Archives/Computing/2015 March 9

= March 9 =

Recovering data from a failing/bad sector'd hard drive?
Title says all. Does anyone know of a safe way to retrieve data off my HGST (besides sending the drive to some of you guys and spending a fortune for recovery)? Merely copy-pasting files from it to a safe location isn't going to cut it, as I'd risk ending up with even more bad sectors. Blake Gripling (talk) 06:31, 9 March 2015 (UTC)
 * There is no "safe way". Bad sectors are just that - bad. Expect some losses. I have however had a lot of luck with SpinRite. Run a chkdsk after using SpinRite. I also found this useful: https://www.ultimatebootcd.com/ Use it to copy your data in a non-Windoze environment. 196.213.35.146 (talk) 13:28, 9 March 2015 (UTC)
 * Similar things have been discussed many times before on the RDC. But basically 196 is correct there is no "safe way" although I wouldn't touch SpinRite. Instead, your best bet is proably to use something that can image the partition (if it's only one) or disk. dd on *nix is a common recommendation, but this isn't really something that hard. (Edit: By which I mean there are lots of tools which can do this sort of thing.) You will need enough disk space for the entire partition/disk image, so make sure you have that before you start. In the meantime, make sure the hard disk isn't powered on. If the amount of data you want to recover is only a small percentage of the disk, it may instead be better to use something which can understand the filesystem but won't write to it and copy only those files first before you try imaging. Nil Einne (talk) 14:05, 9 March 2015 (UTC)
 * You're better of using ddrescue than dd ; ddrescue will skip over sectors that it can't read whereas dd will keep retrying. ddrescue will also keep a log of how far it has got - which is useful if the source disk runs correctly for a short period after power-up, and then freezes. However, unless you are familiar with *nix, dd and ddrescue aren't very user-friendly. LongHairedFop (talk) 14:12, 9 March 2015 (UTC)
 * Yeah sorry should have recommended ddrescue, I forgot the discussions I'd read before and it's been a while since I did anything like this. If you are not sure if you can work out how to use ddrescue, UltimatebootCD and similar bootable recovery stuff have a number of tools capable of imaging. If you want to do it on Windows, if the disk has never been mounted you can probably simply turn off automounting and give the chkdsk on startup a long timeout or turn it off to stop anything happening to it. If it's been mounted before, turning off auto mounting won't help, you'd need remove it from the list of stuff Windows will mount. (In reality you probably won't cause much damage by mounting and then unmount, but you really want to keep anything like that to a minimum. I'm presuming of course there hasn't been sufficient file system damage that stuff could end up being overwritten because the OS is confused.) Nil Einne (talk) 21:15, 9 March 2015 (UTC)