Saturday, August 30, 2008

status of create/drop node(group)

status:
create/drop nodegroup now works with one noticeable exception
replication cant be connected while the nodegroup is added.
i'll try to find time to fix this next week.

howto:
- start a 2 node cluster
- create table T1
- stop ndb_mgmd, add 2 nodes, start ndb_mgmd
- either stop the 2 running nodes and restart all 4
or rolling restart the 2 running nodes, and then start the 2 new nodes
- ndb_mgm> create nodegroup n1,n2
- alter table T1 add partitions partitions 2

Tata! fully online scaling of the cluster

howto backwards:
- drop table T1
- ndb_mgm> drop nodegroup X
- ndb_mgm> n1,n2 stop -a
- stop ndb_mgmd, remove the 2 nodes, start ndb_mgmd
- either stop the 2 running nodes and restart them
or rolling restart them

(A nodegroup is allowed to be dropped if it does not contain any data)

side effect:
- I added the possibility to specify nodegroups per node in the config-file
(this I intend to use for testing, but maybe someone might find it interesting)

future:
- magnus is working on "online configuration change" in the ndb_mgmd
once this is complete/functional, we can add the "add node"-command
so that the entire procedure can be done wo/ node restarts.

---

2 comments:

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Parry said...

Hi Jonas,

I have three nodegroups in my cluster. I want to drop third nodegroup. I had created one database only and there was only one table inside that database.

I tried to drop the third node group but I got the error message "ndb_mgm> drop nodegroup 2;
* 1006: Illegal reply from server
* error: -2
"

I dropped the table but still got above error, then I dropped the only database I had created but still getting same error.

I had shutdown all the nodes and restarted management server with --reload option and datanodes with --initial option but still getting same error and unable to drop node group.

Will appreciate your help on this.


ndb_mgm> show
Cluster Configuration
---------------------
[ndbd(NDB)] 6 node(s)
id=3 @192.168.**.*3 (mysql-5.5.20 ndb-7.2.5, Nodegroup: 0, Master)
id=4 @192.168.**.**4 (mysql-5.5.20 ndb-7.2.5, Nodegroup: 0)
id=5 @192.168.**.**5 (mysql-5.5.20 ndb-7.2.5, Nodegroup: 1)
id=6 @192.168.**.**6 (mysql-5.5.20 ndb-7.2.5, Nodegroup: 1)
id=7 @192.168.**.**7 (mysql-5.5.20 ndb-7.2.5, Nodegroup: 2)
id=8 @192.168.**.**8 (mysql-5.5.20 ndb-7.2.5, Nodegroup: 2)

[ndb_mgmd(MGM)] 1 node(s)
id=1 @192.168.**.**1 (mysql-5.5.20 ndb-7.2.5)

[mysqld(API)] 54 node(s)
id=50 (not connected, accepting connect from 192.168.**.**3)
id=51 (not connected, accepting connect from 192.168.**.**4)
id=52 (not connected, accepting connect from 192.168.**.**5)
id=53 (not connected, accepting connect from 192.168.**.**6)