[Info-vax] OT: For MAC Lovers Only :-)

[Stephen Hoffman]

On 2012-10-16 20:40:44 +0000, JF Mezei said:

> On 12-10-16 15:51, glen herrmannsfeldt wrote:
> 
>> No, the "read track" command, at least for the WD controllers,
>> isn't that useful. You don't know where the sectors start!
> 
> Touché. I was erroneously  thinking "block" when reading "track".
> 
> Is it fair to state that sector = block in most cases ?

That depends on your definition of "most"...

A VMS block is 512 bytes.

Some disks commonly found on VMS use 2048-byte sectors (eg: optical), 
and various new (magnetic) disks are increasingly using 4096-byte 
sectors.

You just knew there was going to be a link, right?  
<http://labs.hoffmanlabs.com/node/284>

There are also cases (on VMS) where one block is comprised of two or 
four sectors, too.  (I know of two reasonably well-known devices where 
the sectors were smaller than a VMS block.  There may be more.  I'll 
leave it to the reader to figure out which devices...)


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