Friday, January 11, 2013

Post 45 of Series - Space calculation and analysis in case of NORMAL redundancy on ASM




SHALOK, THIRD MEHL

Without serving the True Guru, the soul is
in the bondage of deeds done in ego. Without serving the True Guru, one finds no place of rest; he dies, and is reincarnated, and continues coming and going.Without serving the True Guru, one?s speech is vapid and insipid; the Naam, the Name of the Lord, does not abide in his mind. O Nanak, without serving the True Guru, they are bound and beaten in the City of Death; they arise and depart with blackened
faces. || 1 ||






Here is the output of lsdg on ASM as of now.

ASMCMD> lsdg
State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512   4096  1048576      6144     1847                0            1847              0             N  DATA/
MOUNTED  EXTERN  N         512   4096  1048576      2048      738                0             738              0             N  FLASH/
MOUNTED  EXTERN  N         512   4096  1048576      2048     1652                0            1652              0             Y  GRID/
MOUNTED  NORMAL  N         512   4096  1048576     12288    12123             2048            5037              0             N  TESTING/
ASMCMD>

1. Used 6 disks of 2048 each to create the disk group TESTING (Redundancy is of NORMAL), so total space used is 12288 MB.
2. Some of the space is used in headers so the space FREE in the diskgroup is 12123 MB.
3. Since we are using a mirroring of NORMAL, Oracle is reserving 2048 for failover if it occurs.
4. Usable_file_MB =  (Free_MB - Req_mir_free_MB)/2
5. i.e. Usable_file_MB=(12123-2048)/2 = 5037 MB


Now create a data file of 1024MB on this diskgroup

11:27 : oracle : rac1.rac.meditate.com : @GSINGH1 : /home/oracle
$ . oraenv
ORACLE_SID = [GSINGH1] ? emgc1
The Oracle base remains unchanged with value /u01/app/oracle

11:27 : oracle : rac1.rac.meditate.com : @emgc1 : /home/oracle
$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Fri Jan 11 11:27:12 2013

Copyright (c) 1982, 2011, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options

SQL>  create tablespace TESTING datafile '+TESTING' size 1024M autoextend off;

Tablespace created.

SQL> SQL>



How it looks on ASM as of now?


11:28 : oracle : rac1.rac.meditate.com : @+ASM1 : /home/oracle
$ asmcmd
ASMCMD> lsdg
State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512   4096  1048576      6144     1847                0            1847              0             N  DATA/
MOUNTED  EXTERN  N         512   4096  1048576      2048      738                0             738              0             N  FLASH/
MOUNTED  EXTERN  N         512   4096  1048576      2048     1652                0            1652              0             Y  GRID/
MOUNTED  NORMAL  N         512   4096  1048576     12288    10049             2048            4000              0             N  TESTING/
ASMCMD>


1. Total space is same as 12288 which includes all luns including the mirroring luns.
2. Earlier free space available was 12123 MB. Now is 12123-(1024*2(Multiply by 2 as its used by mirroring)=10075 MB. Some MB used for header update so FREE MB is : 10049MB (is as shown)
3. Since we are using a mirroring of NORMAL, Oracle is reserving 2048 for failover if it occurs same as earlier.
4. Usable_file_MB =  (Free_MB - Req_mir_free_MB)/2
5. i.e. Usable_file_MB=(10049-2048)/2 = 4000 MB


11:38 : oracle : rac1.rac.meditate.com : @ : /home/oracle
$ . oraenv
ORACLE_SID = [oracle] ? emgc1
The Oracle base has been set to /u01/app/oracle

11:38 : oracle : rac1.rac.meditate.com : @emgc1 : /home/oracle
$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Fri Jan 11 11:38:57 2013

Copyright (c) 1982, 2011, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options

SQL> create tablespace TESTING1 datafile '+TESTING' size 4096m autoextend off;

Tablespace created.

SQL>

11:42 : oracle : rac1.rac.meditate.com : @+ASM1 : /home/oracle
$ asmcmd
ASMCMD> lsdg
State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512   4096  1048576      6144     1847                0            1847              0             N  DATA/
MOUNTED  EXTERN  N         512   4096  1048576      2048      738                0             738              0             N  FLASH/
MOUNTED  EXTERN  N         512   4096  1048576      2048     1652                0            1652              0             Y  GRID/
MOUNTED  NORMAL  N         512   4096  1048576     12288     1852             2048             -98              0             N  TESTING/
ASMCMD>

1. Total space is same as 12288 which includes all luns including the mirroring luns.
2. Earlier free space available was 12123 MB. Now is 10049-(4096*2(Multiply by 2 as its used by mirroring))=1857 MB. Some MB used for header update so FREE MB is : 1852 MB (is as shown)
3. Since we are using a mirroring of NORMAL, Oracle is reserving 2048 for failover if it occurs same as earlier.
4. Usable_file_MB =  (Free_MB - Req_mir_free_MB)/2
5. i.e. Usable_file_MB=(1852-2048)/2 = -98 MB

Remember now we are not protected for the failure of teh disk. Oracle strongly recomends to add space before we go to miuns or approach near zero usable space.



BHAIRAO, FIFTH MEHL

Even though he may be fed with
hundreds of longings and yearnings, still the faithless cynic does not remember the Lord, Har, Har. || 1 || Take in the teachings of the humble Saints. In the Saadh Sangat, the Company of the Holy, you shall obtain the supreme status. || 1 || Pause || Stones may be kept under water for a long time. Even so, they do not absorb the water; they remain hard and dry. || 2 || The six Shaastras may be read to a fool, but it is like the wind blowing in the ten directions. || 3 || It is like threshing a crop without any corn ? nothing is gained. In the same way, no benefit comes from the faithless cynic. || 4 || As the Lord attaches them, so are all attached. Says Nanak, God has formed such a form.




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