Subject: Re: Work-in-progress "wedges" implementation
To: Daniel Carosone <>
From: Jason Thorpe <>
List: tech-kern
Date: 09/22/2004 15:16:26
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On Sep 22, 2004, at 2:34 PM, Daniel Carosone wrote:

>>            Wedges may not be created on a disk if any partition other
>>            than RAW_PART is open.
> Is this a current limitation, or an intended permanent feature?

Intended permanent feature.  In fact, once we have fully transitioned 
to wedges, I would like for the old partition-style access of disks to 
go away completely.

>>         5. My patch includes modifications to make wedges work with 
>> the
>>            "wd" driver.  I will convert the other disk drivers over
>>            time.  An outstanding question: What should we do about
>>            floppy drives?
> Removable media are one of the most useful cases for named
> partitions.

The line is fairly blurred about what is and what is not removable 
media these days.  Consider Fibre Channel and iSCSI ... is your big 
RAID array removable media?  Well, no, but because it's on a network, 
it "sort of" is :-)

> It should be reasonably simple to have a wedge discovery
> that looks at the volume name from a fat, iso9660 etc fs and creates a
> wedge corresponding to that name. Having a (constant) path-based name
> would also be good (for when you don't care).

Can you give me an example of the type of path-based name you're 
talking about?  You mean like WWN?  A WWN only names the disk, not the 
partitions on it...

> The other aspect of floppies is the current hack to encode density
> info into the partition bits. I've never really liked that, but I'm
> not sure what to do with it either. Again, maybe there are
> (overlapping) wedges created and named according to the drive's
> supported densitites?

I haven't tried to address floppy density issues here.  Currently, 
wedges are not allowed to overlap, and I don't think floppy density is 
a problem appropriately solved with wedges.

> Many fd's these days are presented to us as sd (via usb) anyway, so a
> more generic solution is needed.

Do those drives even work with 720K disks?

         -- Jason R. Thorpe <>

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