Adding more people to get a consensus about this.
On Tue, Jun 20, 2017 at 1:49 PM, Aravinda <avishwan@xxxxxxxxxx> wrote:
regards
Aravinda VKNo. But the necessary change can be made to Geo-rep code as well if format is changed, Since all these are built/shipped together.
On 06/20/2017 01:26 PM, Xavier Hernandez wrote:
Hi Pranith,
adding gluster-devel, Kotresh and Aravinda,
On 20/06/17 09:45, Pranith Kumar Karampuri wrote:
On Tue, Jun 20, 2017 at 1:12 PM, Xavier Hernandez <xhernandez@xxxxxxxxxx
<mailto:xhernandez@xxxxxxxxxx>> wrote:
On 20/06/17 09:31, Pranith Kumar Karampuri wrote:
The way geo-replication works is:
On each machine, it does getxattr of node-uuid and check if its
own uuid
is present in the list. If it is present then it will consider
it active
otherwise it will be considered passive. With this change we are
giving
all uuids instead of first-up subvolume. So all machines think
they are
ACTIVE which is bad apparently. So that is the reason. Even I
felt bad
that we are doing this change.
And what about changing the content of node-uuid to include some
sort of hierarchy ?
for example:
a single brick:
NODE(<guid>)
AFR/EC:
AFR[2](NODE(<guid>), NODE(<guid>))
EC[3,1](NODE(<guid>), NODE(<guid>), NODE(<guid>))
DHT:
DHT[2](AFR[2](NODE(<guid>), NODE(<guid>)), AFR[2](NODE(<guid>),
NODE(<guid>)))
This gives a lot of information that can be used to take the
appropriate decisions.
I guess that is not backward compatible. Shall I CC gluster-devel and
Kotresh/Aravinda?
Is the change we did backward compatible ? if we only require the first field to be a GUID to support backward compatibility, we can use something like this:
Geo-rep uses node-id as follows,
list = listxattr(node-uuid)
active_node_uuids = list.split(SPACE)
active_node_flag = True if self.node_id exists in active_node_uuids else False
Bricks:
<guid>
AFR/EC:
<guid>(<guid>, <guid>)
DHT:
<guid>(<guid>(<guid>, ...), <guid>(<guid>, ...))
In this case, AFR and EC would return the same <guid> they returned before the patch, but between '(' and ')' they put the full list of guid's of all nodes. The first <guid> can be used by geo-replication. The list after the first <guid> can be used for rebalance.
Not sure if there's any user of node-uuid above DHT.
Xavi
Xavi
On Tue, Jun 20, 2017 at 12:46 PM, Xavier Hernandez
<xhernandez@xxxxxxxxxx <mailto:xhernandez@xxxxxxxxxx>
<mailto:xhernandez@xxxxxxxxxx <mailto:xhernandez@xxxxxxxxxx>>>
wrote:
Hi Pranith,
On 20/06/17 07:53, Pranith Kumar Karampuri wrote:
hi Xavi,
We all made the mistake of not sending about changing
behavior of
node-uuid xattr so that rebalance can use multiple nodes
for doing
rebalance. Because of this on geo-rep all the workers
are becoming
active instead of one per EC/AFR subvolume. So we are
frantically trying
to restore the functionality of node-uuid and introduce
a new
xattr for
the new behavior. Sunil will be sending out a patch for
this.
Wouldn't it be better to change geo-rep behavior to use the
new data
? I think it's better as it's now, since it gives more
information
to upper layers so that they can take more accurate decisions.
Xavi
--
Pranith
--
Pranith
--
Pranith
--
Pranith
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