"Andreas Bollhalder" <[EMAIL PROTECTED]> > > I tried the math on my WinXP host with Win2k guest. > > When using the following math with my 8192MB QCOW image, QEMU refuse > to start: > > 1 Block = 512 Bytes > > Cylinders = Blocks / (Heads * Sectors) > > (kBytes * 2) / (16 * 63) > (8388608 kBytes * 2) / (16 * 63) > > For 8192MB Image: -hdachs 16644,16,63
Yeah. Sorry about that. You probably want to use something like 64 heads and 63 or 255 sectors/cylinder in this case. I expect that 16000 heads is probably a bit much. IIRC, Solaris tends to barf on big volumes that have really big c/h/s translations. > I brute forced the cylinder value, QEMU will start with a lower or > equal value of 16383 cylinders. Very interesting. Wonder if that's some of ide limit. > > I made my own math based on this: > > Cylinders = Blocks / (Heads * (Sectors + 1)) - 1 > > (kBytes * 2) / (16 * 64) - 1 > (8388608 kBytes * 2) / (16 * 64) - 1 > > For 8192MB Image: -hdachs 16383,16,63 well, you should be able to make it ~4100 cylinders just by increasing the heads from 16 to 64. > > > I'm realy confused about what's right or not. I created the image with > the QEMU Manager. Can anyone explain this ??? I think the large number of cylinders is a *bad* thing. Sorry if I don't have a more technical term. It's not from looking at the code, but from field experience when dealing with really big Luns on a SAN. Ben > > Andreas > > > Ben Taylor wrote: > > > I forgot one very important part. The calculation needs > > to be <img size in bytes> / (heads * sectors per cylinder > > * 512 bytes) = cylinders. so in your case, the calculation is close > > > well, the default sector size is 512, and you've done > > your sizing in number of 1k blocks, your calculations was > > close. It should be: > > > > blocks secs/block hds sec/cyl > > > > (2 000 000 * 2 ) / ( 16 * 63 ) = 3968 > > > The first time I did the math, my 2g partition went > > to 8g partition when I used the -hdachs parameters > > cause I really screwed up the math. (it appears if > > you mess your c-h-s values, your image since may > > change. :-) > > > HTH, and sorry for the confusion. > > > Ben > > > > _______________________________________________ > Qemu-devel mailing list > Qemu-devel@nongnu.org > http://lists.nongnu.org/mailman/listinfo/qemu-devel > _______________________________________________ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
