| Topic: | Re:Re:Re:Re:Re:Re:Where can computers be recycled in Ealing? | |
| Posted by: | Chris Bell | |
| Date/Time: | 21/02/10 10:02:00 |
| Please let me know if you find this easy or difficult to understand, or need help. Blanking a hard disc: A simple re-format leaves data which could be recovered, a re-format combined with over-writing every bit of data within the filing system can still leave data, including a virus, on the first few sectors of the disc, so I use a combination of methods. I normally use a computer running either on an installed Linux operating system or a bootable "Live" Knoppix DVD or CD. Knoppix will not install anything or write to your discs unless you instruct it to do so. I will assume that you are using Knoppix, any Linux will provide similar facilities. You will need administrator status to be able to re-format the disc, but there is no administrator password configured for the Knoppix disc so do not attempt to provide one. Shut down the computer and remove the mains power before connecting the drive to the computer. If you are using Knoppix place the disc in the CDROM drive and then boot the computer. The hard disc drive will be named according to its type and location. A partition on an IDE connected drive will be listed as /dev/hdxn, while a partition on most other kinds of disc will be /dev/sdxn, where x is replaced by a, b, c, d.... and n is the partition reference number. Ensure that you are looking at the correct drive by examining its contents using the Knoppix disc facilities. (There may be a drive icon on screen depending on the version of Knoppix in use). Close any window that displays the disc contents and then "unmount" (dismount or forget the contents of the disc) the disc, usually click with the righthand mouse button over the disc icon to select the menu and select unmount. Open a text "terminal" window, and obtain administrator privilege by entering "su". You may also need to enable disc writes using the righthand mouse button menu. You can blank the first few sectors by copying from a series of zeros: dd if=/dev/zero of=/dev/hdx or according to the type of disc dd if=/dev/zero of=/dev/sdx You can cancel the above after a short time using Next install a single large partition covering the entire available disc space, mark the partition bootable, and write the new partition table using cfdisk /dev/hdx (or perhaps /dev/sdx) You should find cfdisk fairly obvious to use, including deleting unwanted partitions, creating new partitions, and marking the first partition as bootable. Next format the entire partition and write-then-read a series of patterns to the entire space on the partition using mke2fs. The e2fs format is a Linux format, not understood by standard Microsoft, and any faulty sectors found will be listed. This will take a long time depending on the size of disc and processor speed, I just leave it running and wait until it has finished. It is the "-c -c" that instructs it to do a full write-then-read test with multiple patterns which will over-write every part of the disc within the partition at least three times. mke2fs -c -c /dev/hdx1 (or /dev/sdx1) The disc will need to be re-formatted for use with Microsoft, but you can use a simple fast format. |