With respect to using a seed - the facility to supply one to the
rebalance operation has recently been added to puppet-swift master
branch (commit b8b4434), however the seed parameter is not available to
any of the usual calling methods (this looks to be deliberate from the
commit message), so is not immediately useful without surgery :-)
Regards
Mark
On 13/06/15 18:05, Mark Kirkwood wrote:
From what I can see, the ring gets created and rebalanced in
puppet-swift/manifest/ringbuilder.pp i.e calling:
class { '::swift::ringbuilder':
# the part power should be determined by assuming 100 partitions
per drive
part_power => '18',
replicas => '3',
min_part_hours => 1,
require => Class['swift'],
}
*not* when each device is added.
Yeah, using a seed is probably a good solution too. For the moment I'm
using the idea of one proxy being a 'ring server/master' which achieves
the same thing (identical rings everywhere). However I'll have a look at
using a seed, as this may simplify the code and also the operational
procedure needed to replace said 'master' if it fails (i.e to avoid
accidentally creating a new ring when you really don't need to...)
Regards,
Mark
On 12/06/15 23:10, McCabe, Donagh wrote:
I skimmed the code, but since I'm not familiar with the environment, I
could not find where "swift-ring-builder rebalance" is invoked. I'm
guessing that each time you add a device to a ring, a rebalance is
also done. Leaving aside how inefficient that is, the key thing is
that the rebalance command has an optional "seed" parameter. Unless
you explicitly set the seed (to same value on all node obviously), you
won't get the same ring on all nodes. You also need to make sure you
add the same set of drives and in same order.
Regards,
Donagh
-----Original Message-----
From: Mark Kirkwood [mailto:mark.kirkw...@catalyst.net.nz]
Sent: 12 June 2015 06:28
To: OpenStack Development Mailing List (not for usage questions)
Subject: [openstack-dev] [puppet] [Swift] Multiple proxy recipes will
create out of sync rings
I've looking at using puppet-swift to deploy a swift cluster.
Firstly - without
http://git.openstack.org/cgit/stackforge/puppet-swift/tree/tests/site.pp
I would have struggled a great deal more to get up and running, so a
big thank you for a nice worked example of how to do multiple nodes!
However I have stumbled upon a problem - with respect to creating
multiple proxy nodes. There are some recipes around that follow on
from the site.pp above and explicitly build >1 proxy (e.g
https://github.com/CiscoSystems/puppet-openstack-ha/blob/folsom_ha/examples/swift-nodes.pp)
Now the problem is - each proxy node does a ring builder create, so
ends up with *different* builder (and therefore) ring files. This is
not good, as the end result is a cluster with all storage nodes and
*one* proxy with the same set of ring files, and *all* other proxies with
*different* ring (and builder) files.
I have used logic similar to the attached to work around this, i.e
only create rings if we are the 'ring server', otherwise get 'em via
rsync.
Thoughts?
Regards
Mark
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