Re: Converting existing partition to bcache backing device without loss of data

[Jason Warr <jason-/cow75dQlsI@public.gmane.org>]

On 08/08/2013 11:27 AM, Adam Brenner wrote:
> Howdy,
>
> I am in the process of testing bcache on our HPC cluster to act as
> cache for our gluster storage (~750TB).
>
> I notice that during the setup process on our test cluster, our
> backing device (where all our data is stored) will need to be
> formatted in order to support bcache.
You can't convert an in use block device into a backing store. 

Your best bet is to replace your gluster bricks either one at a time or
in acceptable groups with bricks that are bcache backed.

But without knowing more about how your gluster setup is architect-ed
this is just a guess.
> Does a way exist so we do not have to format our backing device? Or is
> working being done to support this?
In your particular case converting in place is not likely a very good
method even if it were supported.  Gluster is designed to be flexible in
such a way that you can replace existing storage bricks with new and
improved bcache backed bricks by simply replacing a replica in a set.
>
> Thanks,
> -Adam
>
> --
> Adam Brenner
> Computer Science, Undergraduate Student
> Donald Bren School of Information and Computer Sciences
>
> Research Computing Support
> Office of Information Technology
> http://www.oit.uci.edu/rcs/
>
> University of California, Irvine
> www.ics.uci.edu/~aebrenne/
> aebrenne-sXc7qaQca9o@public.gmane.org
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