Date   : Sun, 06 Mar 2005 00:11:07 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Acorn Winchester unit

jgh@... (Jonathan Graham Harston) wrote:
> > In my SJ Research's MDFS there is such a drive too.
> > Perhaps also using 256 bytes per sector?
>  
> MDFS floppies used 1024byte sectors, the filesystem uses 1024 blocks, I'm
> inclined to beleive that the MDFS hard drives use 1024byte sectors -
> either that or 256byte sectors used in groups of 4.
 
I tell a lie. The MDFS does indeed use 1024-byte sectors on floppy
disks, but upon checking the manual, the MDFS appears to use
512-byte sectors, so it must arrange them into logical blocks of
two physical sectors.  The MDFS uses logical blocks of 1024 bytes
at all other levels, which is why the maximum size of a partition
is 61M.  65536 blocks of 1024 bytes gives 64M. This is reduced
slightly to 61M as at the time the largest available backup tapes
were only 61M.
 
Hmmm. Wonder if I can patch my fileserver code to allow full 64M
partitions? As I understand the code so far, the fileserver code
just believes what's in the disk structure map. So, as long as the
formatter/partitioner sets that up to correctly specify a 64M
parition, the FS code should just use it transparently.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
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