Rational/R1000s400/DiskLayout/ObjectStore

Rational R1000 Object Store

The object-store occupies slice 3 of the disk and the layout is "for futher study"

A bitmap tracks sectors in use, this bitmap covers all of the disk up to some point in slice4, which might be there only as "rounding buffer" for the free bitmap.

The Sector Use Bitmap Index

The third and fourth sectors in slice 3 are identical, and contain a list of the Bitmap Sectors.

64b	0x8000000000000000
6b	Encodes volume number. Values seen: volume1 = 0x21, volume2 = 0x2
24b	Sector number of third sector in slice 3
32b	Unknown
(10b,24b) * 237	(flag, sector number) Flag values seen 0x03 and 0x203, 0x1fe, 0x3fe. The latter two marks unused list entries.
6b	Unused?

Sector use Bitmaps

These sectors are also doubled, the first occupies the first two sectors of slice 3, the rest follow from the fifth sector onwards.

64b	0x8000000000000002
6b	Encodes volume number. Values seen: volume1 = 0x21, volume2 = 0x2
24b	Sector number of the first of the two copies
1b	0x1
(10b,1024b) * 7	(flag, bitmap) Flag values seen: 0x2 All of volume1and most of volume2 0x202 Some of volume2, follows a fixed pattern 0x1ff Marks unused bitmaps