Re: [Drbd-dev] New Features: write-back cache mode

[Lars Ellenberg <lars.ellenberg@linbit.com>]

On Sat, Sep 20, 2008 at 05:04:44PM -0600, Morey Roof wrote:
> This is pretty much what I was thinking.  For the btree, generations,  
> and ref-count a good example to look at is how btrfs (This is the other  
> project I have started to mess with) works.  The design is very  
> efficient and I think we could use a very close match for our setup.  I  
> haven't read the paper you sent yet but will get to that today.
>
> Let me know how you would like to start and I can start working a proof  
> of concept and we can see how to go from there.

I still think that should be implemented as a
generic device-mapper write-back target,
not as part of drbd.

there is already some caching target out there somewhere,
using small local low-latency disks as cache
for higher latency "remote" iSCSI or GNBD disks.
At least I read something like that
on one of the linux thin clients projects a while ago.
I did not look at the code, and never used it, though.
a 10 second google suggests that
http://www.acis.ufl.edu/~ming/dmcache/
is what I mean.

maybe you can use that as a starting point,
and point it to a ram disk as cache?


-- 
: Lars Ellenberg                
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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