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From Matthew Allen <matthew.j.al...@gmail.com>
Subject Multi-DC Repairs and Token Questions
Date Wed, 28 May 2014 05:25:54 GMT
Hi,

Am a bit confused regarding data ownership in a multi-dc environment.

I have the following setup in a test cluster with a keyspace with
(placement_strategy = 'NetworkTopologyStrategy' and strategy_options =
{'DC_NSW':2,'DC_VIC':2};)

Datacenter: DC_NSW
==========
Replicas: 2
Address         Rack        Status State   Load
Owns                Token

0
nsw1  rack1       Up     Normal  1007.43 MB      100.00%
-9223372036854775808
nsw2  rack1       Up     Normal  1008.08 MB      100.00%             0


Datacenter: DC_VIC
==========
Replicas: 2
Address         Rack        Status State   Load
Owns                Token

100
vic1   rack1       Up     Normal  1015.1 MB       100.00%
-9223372036854775708
vic2   rack1       Up     Normal  1015.13 MB      100.00%             100

My understanding is that both Datacenters have a complete copy of the data,
but when I run a repair -pr on each of the nodes, the vic hosts only take a
couple of seconds, while the nsw nodes take about 5 minutes each.

Does this mean that nsw nodes "own" the majority of the data given their
key ranges and that repairs will need to cross datacenters ?

Thanks

Matt

command>nodetool -h vic1 repair -pr   (takes seconds)
Starting NodeTool
[2014-05-28 15:11:02,783] Starting repair command #1, repairing 1 ranges
for keyspace MY_KEYSPACE
[2014-05-28 15:11:03,110] Repair session
76d170f0-e626-11e3-af4e-218541ad23a1 for range
(-9223372036854775808,-9223372036854775708] finished
[2014-05-28 15:11:03,110] Repair command #1 finished
[2014-05-28 15:11:03,126] Nothing to repair for keyspace 'system'
[2014-05-28 15:11:03,126] Nothing to repair for keyspace 'system_traces'

command>nodetool -h vic2 repair -pr (takes seconds)
Starting NodeTool
[2014-05-28 15:11:28,746] Starting repair command #1, repairing 1 ranges
for keyspace MY_KEYSPACE
[2014-05-28 15:11:28,840] Repair session
864b14a0-e626-11e3-9612-07b0c029e3c7 for range (0,100] finished
[2014-05-28 15:11:28,840] Repair command #1 finished
[2014-05-28 15:11:28,866] Nothing to repair for keyspace 'system'
[2014-05-28 15:11:28,866] Nothing to repair for keyspace 'system_traces'

command>nodetool -h nsw1 repair -pr (takes minutes)
Starting NodeTool
[2014-05-28 15:11:32,579] Starting repair command #1, repairing 1 ranges
for keyspace SN_KEYSPACE
[2014-05-28 15:14:07,187] Repair session
88966430-e626-11e3-81eb-c991646ac2bf for range (100,-9223372036854775808]
finished
[2014-05-28 15:14:07,187] Repair command #1 finished
[2014-05-28 15:14:11,393] Nothing to repair for keyspace 'system'
[2014-05-28 15:14:11,440] Nothing to repair for keyspace 'system_traces'

command>nodetool -h nsw2 repair -pr (takes minutes)
Starting NodeTool
[2014-05-28 15:14:18,670] Starting repair command #1, repairing 1 ranges
for keyspace SN_KEYSPACE
[2014-05-28 15:17:27,300] Repair session
eb936ce0-e626-11e3-81e2-8790242f886e for range (-9223372036854775708,0]
finished
[2014-05-28 15:17:27,300] Repair command #1 finished
[2014-05-28 15:17:32,017] Nothing to repair for keyspace 'system'
[2014-05-28 15:17:32,064] Nothing to repair for keyspace 'system_traces'

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