Re: dm-cache module

[Heinz Mauelshagen <heinzm@redhat.com>]

On Wed, 2010-04-28 at 03:33 +0200, Olivier B. wrote:
> On 22/03/2010 16:05, Heinz Mauelshagen wrote:
> > On Sun, 2010-03-21 at 00:56 -0400, Ming Zhao wrote:
> >    
> >> Hi Mike,
> >>
> >> Thank you very much for your advice!
> >>
> >> I can revise dm-cache code and resubmit it as you suggested. I would
> >> also love to know Heinz's progress on his implementation and work with
> >> him if there anything I could contribute.
> >>      
> > Hi all,
> >
> > this is a list of the functions of my dm-hstore
> > device-mapper target implementation:
> >
> > o caches reads and writes keeping persistent state metadata.
> > o writes back in order to enhance streaming performance
> >    on fragmented access pattern.
> > o can run on top of readonly original device
> > o if so, writes back any dirty areas when set readwrite
> >    (useful for tests)
> > o readonly<->  readwrite access changes supported via message interface
> > o initializes metadata for extents in cache in the background
> >    in order to fasten cache construction
> > o supports cache resizing via message interface or constructor
> > o keeps metadata persistent by default
> > o stores CRCs with metadata for integrity checks
> > o stores versions with metadata to support future metadata migration
> >
> > Test features only:
> > o transient cache
> > o cache write through
> >
> >
> > Provides very good performance on SSD cache backing stores.
> >
> > Has been shelved for a while because of other priorities so I need to
> > rebase it to the actual kernel.
> >
> > Regards,
> > Heinz
> >
> >    
> Hi,
> 
> Facebook have just released "FlashCache" : 
> http://github.com/facebook/flashcache
> in the documentation we can read :

> Flashcache is built using the Linux Device Mapper (DM), part of the 
> Linux Storage Stack infrastructure that facilitates building SW-RAID and 
> other components.
> 
> So it's an other implementation of the same concept, no ?

Yes, it looks like it. I'll have a closer look how it differs form mine.

Heinz

> 
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