Minor - P4 The procedure for removing a shard from a sharded cluster is to run the removeShard command twice.
The first invocation will start draining the shard.
Once that is complete, a second invocation will then remove the shard.
However, there is not progress given for when the drain is complete. This makes it quite possibly you may have to run the removeShard command several times, in order to see whether it starts the remove or not.
Also, if you happen to run the removeShard command once the removal is complete, it prints a assertion message:
mongos> db.runCommand(
{ removeShard: "foobar" }
)
{ "code" : 13129, "ok" : 0, "errmsg" : "exception: can't find shard for: foobar" }
as well as a stack trace:
2014-09-19T19:08:19.071+0000 [conn139] Assertion: 13129:can't find shard for: foobar
2014-09-19T19:08:19.107+0000 [conn139] 0xdbc1f1 0xd66309 0xd49536 0xd49a8c 0xc62b78 0xc5a354 0xb764be 0xc5353a 0xb8c9dc 0xc7cae1 0xc528ff 0x6e6f29 0xd714ce 0x39d30079d1 0x39d2ce8b5d
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo15printStackTraceERSo+0x21) [0xdbc1f1]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo10logContextEPKc+0x159) [0xd66309]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo11msgassertedEiPKc+0xe6) [0xd49536]
/opt/mongod27017/mongod/bin/mongos() [0xd49a8c]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo15StaticShardInfo4findERKSs+0x358) [0xc62b78]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo5Shard5resetERKSs+0x34) [0xc5a354]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo11dbgrid_cmds14RemoveShardCmd3runERKSsRNS_7BSONObjEiRSsRNS_14BSONObjBuilderEb+0x16e) [0xb764be]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo7Command22execCommandClientBasicEPS0_RNS_11ClientBasicEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0x2ba) [0xc5353a]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo7Command20runAgainstRegisteredEPKcRNS_7BSONObjERNS_14BSONObjBuilderEi+0x32c) [0xb8c9dc]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo8Strategy15clientCommandOpERNS_7RequestE+0x561) [0xc7cae1]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo7Request7processEi+0x6ef) [0xc528ff]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo21ShardedMessageHandler7processERNS_7MessageEPNS_21AbstractMessagingPortEPNS_9LastErrorE+0x69) [0x6e6f29]
/opt/mongod27017/mongod/bin/mongos(_ZN5mongo17PortMessageServer17handleIncomingMsgEPv+0x4ee) [0xd714ce]
/lib64/libpthread.so.0() [0x39d30079d1]
/lib64/libc.so.6(clone+0x6d) [0x39d2ce8b5d]
Please could we handle this condition more gracefully? (Either by making the assertion message a bit friendlier and/or not dumping out the stack trace like that).