[Openstack] [Swift] Unexplained 404s

Clay Gerrard clay.gerrard at gmail.com
Wed May 25 03:10:45 UTC 2016


At the risk of repeating myself:

On Tue, May 24, 2016 at 5:30 PM, Clay Gerrard <clay.gerrard at gmail.com>
 wrote:

>
> This inconsistency in search depth based on the per-worker error limiting
> may be something worth looking into generally - but it's probably mostly
> hidden on clusters that are going 3 or more nodes deep into handoffs in the
> default case.
>
>
I just don't know how much of an issue it is for clusters where each device
in the nodes iter is going to be on a separate node, probably in
independent failure domais - and you've got to not only wiff multiple
primaries but multiple handoffs too.  More over - you'd have to have *all*
the replicas get past request_node_count or else one of the earlier
replicas is going to service the read anyway without ever noticing the
write that landed further out.  Or even if my theory about error limiting
maybe allowing a PUT to go deeper than the request_node_count holds...

Obviously the data got on second handoff device somehow - it be interesting
to see the transaction logs for the write that did that - but there's a lot
of ifs in there and I'm not sure it's an issue except in the single replica
single node case.  Still sorta interesting I guess...

-Clay
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