Large-scale production installations, and another question
dormando at rydia.net
Sun Jun 29 07:59:21 UTC 2008
> 2) When the client issues the call "Where is file $x?" and it gets
> back a list of locations, does the tracker reply back in random order?
> Or is it always the same? Is it expected that the client take the list
> and randomize them too? Just wondering - if the server always replies
> with "$x is on $y" in the same order and the client always picks the
> first one, that means one server is being hit more often than the
> other. Seems like it would be nice to randomize it (or even smarter
> adding in some better intelligence based on connections/load/etc, but
> random is probably good enough) - I haven't looked at the docs/code
> about this specifically but figured someone could answer it pretty
It's weighted by a few things:
- Nodes that are down are removed.
- If IO monitoring is working, the list of paths are sorted, in order of
least busy nodes.
- If no_verify=0 is set in the get_paths call, paths returned are only
ones which have a valid HEAD response on the storage node. For
performance reasons it's generally a good idea to set no_verify=1.
Unless you cannot return paths that could potentially be
More information about the mogilefs