[Qemu-devel] HD Image Size Limits and hdachs

[Jason Brittain <jason@brittainweb.org>]

This has been asked on this list before, but wasn't answered (I've
scoured the list and docs for the answer and it's not in either one):

What are Qemu's limits for hard drive image files?

For example, if I'm using qcow, how large of an image can I safely use,
say, with Linux host & Linux guest?  It seems like qemu-img lets me
create pretty large images, but in a previous message Fabrice notes that
the maximum parameters for the hdachs switch are: 16383,16,63[,none|lba|auto].
If I understand the math correctly, that yields a maximum of 7 gigabytes:

16383 cyls * 16 heads * 63 sectors * 512 bytes = 8455200768 total bytes,
which comes out to 7Gb.

BUT, I have been creating qcow images 16Gb in size, and they've been
working fine (while NOT using the -hdachs startup switch).  So wouldn't
that mean that qemu is able to guess geometry larger than it accepts on
the command line with -hdachs?  If so, isn't this sort of a bug?

What am I missing here?

Thanks..

-- 
Jason "-headaches" Brittain