[CentOS] Copy on write loop block driver

[Jason Pyeron]

> -----Original Message-----
> From: Jason Pyeron
> Sent: Wednesday, August 27, 2014 0:09
> 
> > -----Original Message-----
> > From: John R Pierce
> > Sent: Tuesday, August 26, 2014 20:11
> > 
> > On 8/26/2014 5:03 PM, Jason Pyeron wrote:
> > > What am I doing wrong here?
> > 
> > A) you don't create anything in /dev, the driver should be 
> > using devfs 
> > to create its own devnodes on the fly as needed.
> 
> I assumed such, but it did not work.
> 
> > 
> > B) you apparently never loaded the driver.     see 
> > http://www.atcomputing.nl/Tools/cowloop/loadunload.html
> > 
> 
> 3.2.0.1 says:
> 
> root at localhost ~/cowloop-3.2.0.1
> # cat RELEASENOTES.3.2.0
> This is version 3.2 of the Copy on Write loop driver 'cowloop'
> by ATComputing in Nijmegen, The Netherlands.
> Release date: September 2009.
> ----
> 
> Cowloop wil be part of the 2.6.31 kernel. This has lead to some
> changes in the cowloop utils. Obviously the kernel module has
> been removed from the distribution, only the utilities remain.
> 
Per http://en.wikipedia.org/wiki/Cowloop

Cowloop (copy-on-write loop driver) was a Linux kernel driver ... Cowloop is now largely deprecated in favor of the device-mapper snapshot target which provides the same functionality.

On to learning device mapper, https://www.kernel.org/doc/Documentation/device-mapper/snapshot.txt

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