| myrescue-bitmap2ppm(2) | System Calls Manual | myrescue-bitmap2ppm(2) |
myrescue-bitmap2ppm - Visualisation of the block bitmap for myrescue
myrescue-bitmap2ppm bitmap-file width [ rows width ] ...
myrescue-stat reads a block bitmap from myrescue(1) and generates a visualisation of each blocks condition.
The image is written to stdout in PPM(5) format. You can pipe the output into one of the netpbm converters or into ImageMagick(1) to convert it to a more common format like PNG.
Successfully copied blocks are shown as green pixels. Yellow-green-ish pixels indicate blocks that could be copied, but it took unusually long, indicating that this area might be near-failing. Yellow blocks have been tried once, but could not be read, red blocks could not be read on multiple attempts. Black pixels indicate blocks that have not yet been handled.
The pixels are arranged left-to right, with the first block in the upper left pixel. The width of the image must be specified on the command line - just pick any value.
In case of partially defective discs you might start by having myrescue do a random jump-around scan (option -J) and continually check the visualized block bitmap. If you are lucky, you might begin to see some structure in the image. If these structures somehow run diagonally, you can adjust the width until you get vertical stripes of defective areas. What this means depends on the internal layout of the disc, but it could be defective heads, platters, sectors, cracks, a factory workers hair, ...
Usually internally discs have different zones, so after a few (hundred?) rows you might see the vertical structures bend off. To adjust the image, you can tell the tool to switch to a different width after a certain number of rows. Repeat this until you identified all zones. The last width will be used up to the end of the bitmap.
The resulting image will have the maximum width necessary to accommodate all zones. Zones with shorter widths will be padded on the right with blue pixels.
You can now use this information to manually fine-tune the myrescue calls to concentrate on areas with higher probability of rescue.
Kristof Koehler <kristofk@users.sourceforge.net>
myrescue(1), ppm(5), ImageMagick(1)
http://myrescue.sourceforge.net/
| February 2018 | myrescue 0.9.6 |