[Linux-cluster] GFS2 as virtual machine disk store

[Gionatan Danti]

Il 29-08-2017 13:13 Steven Whitehouse ha scritto:
> Whatever kind of storage is being used with GFS2, it needs to act as
> if there was no cache or as if there is a common cache between all
> nodes - what we want to avoid is caches which are specific to each
> node. Using individual node caching will still cause issues in case,
> for example, one node has cached a block that another node has
> changed. In that case the node with the cached information will use
> that, rather than rereading from disk which is where the newly changed
> information is. So it is a question of ensuring that all nodes "see"
> the same data at all times,
> 
> Steve

 From my understanding (and I can be wrong...) GFS2 will itself take care 
of cache coherency between hosts.

For example, if:
- node A read a file;
- node B read and write the same file;
- node A re-read the same file;
GFS2 should be able to guarantee a consistent view on the file on both 
nodes. Obviously this come with a price: a significant overhead when 
reading/writing the same (cache) files.

I am missing something?
Thanks.

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Danti Gionatan
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