3 Replies Latest reply: Jan 9, 2013 4:31 AM by Sebastian Solbach -Dba Community-Oracle RSS

    diskgroups is 4 or 2 in my case?

    879152
      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?
          kuljeet singh -
          simply check v$asm_diskgroup;


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