[Coco] Another RBFMAN Question

Gene Heskett gene.heskett at verizon.net
Wed Jun 13 00:19:03 EDT 2007


On Tuesday 12 June 2007, Darren A. wrote:
>Does anyone know if the sectors/clusters containing the ID Sector and
>Allocation Map on an RBF disk are included in the Allocation Map?
>
Yes they are included.

>If so, on a disk with more than one sector-per-cluster, is everything else
>excluded from the cluster(s) containing LSN 0 and the Allocation Map?

Yes AFAIK.

>For 
>example, if there are 4 sectors-per-cluster, and the Allocation Map occupies
>sectors 1 and 2, is sector 3 wasted?

Yes.  But look at it this way, if the drive is big enough to need 4 sector 
clusters, (that is over half a gig right there) then one can afford to waste 
a sector, or even 3 in this case, without worrying about running out of disk.
Besides that, your example is a bit unreal.  If the disk needed 4 sector 
clusters, the allocation map, which cannot exceed 65535 bytes total or 256 
sectors, is going to be at least half that in physical sector count, or over 
32768 bytes.  At 256 bytes per sector, that will be a minimum of 128 sectors 
just for the allocation map.  That's 32+ clusters, so you aren't going to be 
worried about sector 3 at all.   OTOH, since lsn0 is included in the same 
allocation as the start of the allocation bitmap, sectors 130-131 could be 
wasted under the right conditions. :)

>Thanks,
>Darren
>
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-- 
Cheers, Gene
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