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3 Replies Latest reply: Jan 9, 2013 2:31 AM by Sebastian Solbach (DBA Community) RSS

diskgroups is 4 or 2 in my case?

879152 Newbie
Currently Being Moderated
I am using 2 node RAC ASM with 4 diskgroups.

Query 1:

SQL> SELECT dg.name AS diskgroup, SUBSTR(d.name,1,16) AS asmdisk,d.TOTAL_MB, d.FREE_MB, d.path
2 FROM V$ASM_DISKGROUP dg, V$ASM_DISK d;

DISKGROUP ASMDISK TOTAL_MB FREE_MB PATH

DATA FRA_0000 512000 509612 /dev/oracle/fra
OCR FRA_0000 512000 509612 /dev/oracle/fra
VOTING FRA_0000 512000 509612 /dev/oracle/fra
FRA FRA_0000 512000 509612 /dev/oracle/fra
DATA OCR_0000 2048 1685 /dev/oracle/ocr
OCR OCR_0000 2048 1685 /dev/oracle/ocr
VOTING OCR_0000 2048 1685 /dev/oracle/ocr
FRA OCR_0000 2048 1685 /dev/oracle/ocr
DATA VOTING_0000 2048 1889 /dev/oracle/voting
OCR VOTING_0000 2048 1889 /dev/oracle/voting
VOTING VOTING_0000 2048 1889 /dev/oracle/voting
FRA VOTING_0000 2048 1889 /dev/oracle/voting
DATA DATA_0000 1792000 1789792 /dev/oracle/data1
OCR DATA_0000 1792000 1789792 /dev/oracle/data1
VOTING DATA_0000 1792000 1789792 /dev/oracle/data1
FRA DATA_0000 1792000 1789792 /dev/oracle/data1
DATA DATA_0001 1792000 1789802 /dev/oracle/data2
OCR DATA_0001 1792000 1789802 /dev/oracle/data2
VOTING DATA_0001 1792000 1789802 /dev/oracle/data2
FRA DATA_0001 1792000 1789802 /dev/oracle/data2

Query 2:

SQL> select group_number, name, TOTAL_MB, FREE_MB from v$asm_disk_stat;

GROUP_NUMBER NAME TOTAL_MB FREE_MB
------------ ------------------------------ ---------- ----------
4 FRA_0000 512000 509612
2 OCR_0000 2048 1685
3 VOTING_0000 2048 1889
1 DATA_0000 1792000 1789792
1 DATA_0001 1792000 1789802

Query 3:

SQL> show parameter asm_diskgroups

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
asm_diskgroups string OCR, FRA


Query 1 and Query 2 shows I have 4 diskgroups but Query 3 shows only 2 diskgroups why?

Thanks
Solaiman
  • 1. Re: diskgroups is 4 or 2 in my case?
    KuljeetPalSingh Guru
    Currently Being Moderated
    simply check v$asm_diskgroup;


    select group_number,name from v$asm_diskgroup;
  • 2. Re: diskgroups is 4 or 2 in my case?
    879152 Newbie
    Currently Being Moderated
    SQL> select group_number,name from v$asm_diskgroup;

    GROUP_NUMBER NAME
    ------------ ------------------------------
    1 DATA
    2 OCR
    3 VOTING
    4 FRA

    SQL> show parameter asm_diskgroups

    NAME TYPE VALUE
    ------------------------------------ ----------- ------------------------------
    asm_diskgroups string OCR, FRA
    SQL>

    First query shows 4 diskgroups but last query shows 2 diskgroups why?
  • 3. Re: diskgroups is 4 or 2 in my case?
    Sebastian Solbach (DBA Community) Guru
    Currently Being Moderated
    Hi,

    the parameter ASM_DISKGROUPS of an ASM instance, specifies, which diskgroups should get mounted, when ASM starts (it does not specify which diskgroups are existing).

    However the paradigma, when a diskgroup should get mounted has changed with 11gR2. So instead of mounting each and every diskgroup on ASM start, the diskgroups are mounted, when needed.
    So instead of specifying every diskgroup in ASM, the resource, which gets started has a dependency on diskgroups. (You can see this on a database if you do a crsctl stat res -p).
    Also the depending ASM diskgroups for a database resource may be modified with srvctl.

    Regards
    Sebastian

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