Documentation on device-mapper and friends

[Greg Freemyer]

On Mon, Apr 29, 2013 at 12:51 PM, amit mehta <gmate.amit at gmail.com> wrote:
> On Sun, Apr 28, 2013 at 5:24 PM, Greg Freemyer <greg.freemyer at gmail.com> wrote:
>> A nice diagram of the overall storage subsystem is at http://www.thomas-krenn.com/en/oss/linux-io-stack-diagram.html
>>
>> Dm is just a single block in it, but it can help to see where it fits in overall.
>>
>> Btw: that diagram doesn't show the legacy ata driver that creates /dev/hdx style devices.  Has that been dropped while I wasn't paying attention?  I haven't used it in years, but I thought it was still used on embedded systems.
>>
>
> Thank you for sharing the link, but I'm looking for more
> detailed information on I/O stack in Linux, dm-mapper and
> multipath in particular.

I actually assumed others would step in.  I haven't seen any dm docs
outside the kernel tree, but I haven't done and dm work.

I guess you know dm-cache just went into the kernel:
http://lwn.net/Articles/540996/

The primary use case is to use SSD (or similar fast storage) as a
cache for a rotating disk.

I assume you found this very old (and simple) article, but I doubt it
is useful 8 years later: http://lwn.net/Articles/124703/

For more useful links, I often go to wikipedia and follow the links:

You should find:

multi-path faq: http://christophe.varoqui.free.fr/faq.html

multi-path policies: http://christophe.varoqui.free.fr/policies.html

multi-path diagrams: http://christophe.varoqui.free.fr/graphics/

multi-path reference: http://christophe.varoqui.free.fr/refbook.html

Greg