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Tuesday, November 15, 2011

configurations for multiple instances on 4 nodes


How to handle multiple databases without enough memory.


Lets say we have 2 environments that need to use the same 4 node cluster.  Each application has 3 instances.  For simplicity lets call the apps


  • DBFS
  • MSTDB
  • DWDB




Now to separate out the 2 environments lets give each environment it’s own set of database.


DBFSI
MSTDBI
DWDBI
DBFSP
MSTDBP
DWDBP


We have 6 instances from 2 environments that all need to be running on 4 nodes with 96g apiece.


RECOMMENDATION


1)      Split the 4 node cluster in ½ .  Put the Imp systems on the first 2 nodes, and he perf systems on the second 2 nodes.
2)      Create 3 different sets of “databases” and “instances” through srvrctl.  These 3 sets will contain 3 different sets of instances.  Only 1 of these 3 will be up at any time.  They will be the same set of datafiles, just different configurations. By overriding the memory settings in the Init file, and have 3 sets of sids in the SPFILE, this configuration is possible.
3)      Start up the appropriate databases (and instances) for the proper configuration


Database
SGA
instance
Nodes
DBFSI
20g
DBFSI1-DBFSI2
dbnode1/dbnode2
LDBFSI
70g
LDBFSI1-LDBFSI4
dbnode1/dbnode2
dbnode3/dbnode4
SDBPFSI
4g
SDBPFSI1
dbnode1
MSTDBI
20g
MSTDBI1-MSTDBI2
dbnode1/dbnode2
LMSTDBI
70G
LMSTDBI1-LMSTDBI4
dbnode1/dbnode2
dbnode3/dbnode4
SMSTDBI
4g
SMSTDBI1
dbnode2
DWDBI
20g
DWDBI1-DWDBI2
dbnode1/dbnode2
LDWDBI
70G
LDWDBI1-LDWDBI4
dbnode1/dbnode2
dbnode3/dbnode4
SDWDBI
4g
SDWDBI1
dbnode1
DBFSP
20g
DBFSP1-DBFSP2
dbnode3/dbnode4
LDBFSP
70g
LDBFSP1-LDBFSP4
dbnode1/dbnode2
dbnode3/dbnode4
SDBPFSP
4g
SDBPFSP1
dbnode3
MSTDBP
20g
MSTDBP1-MSTDBP2
dbnode3/dbnode4
LMSTDBP
70G
LMSTDBP1-LMSTDBP4
dbnode1/dbnode2
dbnode3/dbnode4
SMSTDBP
4g
SMSTDBP1
dbnode4
DWDBP
20g
DWDBP1-DWDBP2
dbnode3/dbnode4
LDWDBP
70G
LDWDBP1-LDWDBP4
dbnode1/dbnode2
dbnode3/dbnode4
SDWDBP
4g
SDWDBP1
dbnode4




OK, now that I have 3 sets of 6 databases combined, what will the actual configuration choices be ??


Normal configuration showing memory usage


Database
dbnode1
dbnode2
dbnode3
dbnode4
DBFSI
20
20


MSTDBI
20
20


DWDBI
20
20


DBFSP


20
20
MSTDBP


20
20
DWDBP


20
20





Total
60g
60g
60g
60g


Perf Isolated testing of DWDB


Database
dbnode1
dbnode2
dbnode3
dbnode4
DBFSI
20
20


MSTDBI
20
20


DWDBI
20
20


SDBFSP


4

SMSTDBP



4
LDWDBP


70
70





Total
60g
60g
74g
74g














Perf Full testing of DWDB


Database
dbnode1
dbnode2
dbnode3
dbnode4
SDBFSI
4



SMSTDBI

4


SDWDBI

4


SDBFSP


4

SMSTDBP



4
LDWDBP
70g
70g
70
70





Total
74g
78g
74g
74g




You can see that with this configuration, it is possible to carefully manage the Database usage.  The above examples can be used to make any one of the database span the whole machine, while the others sit on one node in a small configuration.

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