On Mon, Nov 23, 2015 at 04:32:37PM +0300, Denis V. Lunev wrote: > From: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > > This specifies Parallels image format as implemented in Parallels Cloud > Server 6.10 > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > Signed-off-by: Denis V. Lunev <d...@openvz.org> > CC: Eric Blake <ebl...@redhat.com> > CC: John Snow <js...@redhat.com> > CC: Stefan Hajnoczi <stefa...@redhat.com> > --- > v2: add license info > switch to offsets from types in field descriptions
Cool! Thanks for publishing a specification. This will help everyone understand the code. > +=== Dirty bitmaps feature === > + > +This feature provides a way of storing dirty bitmaps in the image. The fields > +of its data area are: > + > + 0 - 7: size > + The bitmap size, should be equal to disk size in sectors. > + > + 8 - 23: id > + An identifier for backup consistency checking. > + > + 24 - 27: granularity > + Bitmap granularity, in sectors. I.e., the number of sectors > + corresponding to one bit of the bitmap. Does this need to be a power of 2? > + 28 - 31: l1_size > + The number of entries in the L1 table of the bitmap. > + > + variable: l1 (64 * l1_size bytes) > + L1 offset table (in bytes) > + > +A dirty bitmap is stored using a one-level structure for the mapping to host > +clusters - an L1 table. > + > +Given an offset into the bitmap, the offset in bytes into the image file can > be What are the units of the offset into the bitmap? Is it a bit number (i.e. sector number / granularity)?
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