[Gluster-devel] Improving real world performance by moving files closer to their target workloads

[Derek Price]

gordan at bobich.net wrote:
> Isn't that effectively the same thing? Unless there is quorum, DLM locks 
> out the entire FS (it also does this when a node dies, until it gets 
> definitive confirmation that it has been successfully fenced). For 
> normal file I/O all nodes in the cluster have to acknowledge a lock 
> before it can be granted.

Why?  It requires a meta-data cache, but as long as every node in the 
quorum stores a given file's most recent revision # when any lock is 
granted, even if it doesn't actually sync the file data, then any quorum 
should be able to agree on what the version number of the most 
up-to-date copy of a file is.  All nodes are required to report only if 
you assume that any given file has a small number of "owners" and that 
the querier doesn't know who the owner is.

To remain fault tolerant, this requires that servers make some effort to 
stay up-to-date with the meta-data cache, but maybe this could be dealt 
with efficiently with the DHT someone else brought up?

Regards,

Derek
-- 
Derek R. Price
Solutions Architect
Ximbiot, LLC <http://ximbiot.com>
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