[Gluster-devel] How to make out-of-sync files visible in replication setup

[Ian Rogers]

This "directory of softlinks" would need more information in it to work 
I think.

Remember that the bricks know nothing of each other, and clients don't 
know what other clients get up to either.

Some random thoughts:

1. A client will be making a note like this when it's trying to write a 
file and spots that one of the replica sub-volumes is down
1.1. so the client shouldn't try to store this info in the sub-volumes 
as, by definition, they're in a degraded state.
1.2. the info should include which sub-volumes were up/down to help the 
clients make an informed decision for self-heal

that's as far as I got... ;-)

Ian

On 25/03/2010 09:12, Stephan von Krawczynski wrote:
> Hello all,
>
> during the latest discussion I always wondered how an admin of some
> replication setup can find out easily if the glusterfs is in-sync or at least
> mostly synced or which files are really out-of-sync without using getfattr on
> _all_ files.
> Since you can have millions of files it is obvious that ls -lR over the whole
> tree has chances to never return because of the pure run time.
> So it would be great to have some method of finding only the out-of-sync files
> inside the glusterfs.
> And exactly for that case I would like to make this proposal:
> How about creating an option to specify a directory on each server, where the
> server itself (i.e. glusterfsd) creates a softlink to every file he sets the
> xattrs to a value that implies some of his fellow servers is out-of-sync.
> As soon as this xattr gets cleared the softlink is removed.
> Of course the softlink should point to the full path and not a relative one.
> This would allow to get a replication in-sync simply by stating the files
> pointed to by the softlinks.
> I guess that this idea is easy to implement and trivial in usage. I hope my
> explanation is good enough, if not feel free to ask anything.
> What do you think?
>
>    


-- 
www.ContactClean.com
Making changing email address as easy as clicking a mouse.
Helping you keep in touch.