ASM question

  • From: "Hameed, Amir" <Amir.Hameed@xxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 23 Feb 2007 13:13:42 -0500

Hi Folks,
I have a 10.2.0.2 ASM instance running on Solaris 9 with the following
scenario:

1. All raw disk slices are 5GB in size

2. I have created a normal redundancy ASM diskgroup with two failure
groups as shown below:
SQL> create diskgroup data normal redundancy
failgroup failgroup_1
disk '/dev/vx/rdsk/ux016_RAW/volraw_01'
failgroup failgroup_2
disk '/dev/vx/rdsk/ux016_RAW/volraw_02'
/

When I run the sql statement, as shown below, I see the following
output:
SQL> select GROUP_NUMBER GROUP#, NAME, STATE, TOTAL_MB, FREE_MB,
REQUIRED_MIRROR_FREE_MB REQ_MIRR_FREE_MB, USABLE_FILE_MB
from V$ASM_DISKGROUP;

    GROUP# NAME           STATE             TOTAL_MB    FREE_MB
REQ_MIRR_FREE_MB USABLE_FILE_MB
---------- -------------- --------------- ---------- ----------
---------------- --------------
         1 DATA           MOUNTED              10240      10138
0           5069

So, the total size of the DG is 10GB with Usable space of 5GB. Because
the group is mirrored 1:1, the REQ_MIRR_FREE_MB is zero.

3. When I create the same group with two disks in each failover group, I
see an output that I am not able to comprehend:
SQL> create diskgroup data
failgroup failgroup_1
disk
'/dev/vx/rdsk/ux016_RAW/volraw_01',
'/dev/vx/rdsk/ux016_RAW/volraw_02'
failgroup failgroup_2
disk
'/dev/vx/rdsk/ux016_RAW/volraw_03',
'/dev/vx/rdsk/ux016_RAW/volraw_04'
/

SQL> select GROUP_NUMBER GROUP#, NAME, STATE, TOTAL_MB, FREE_MB,
REQUIRED_MIRROR_FREE_MB REQ_MIRR_FREE_MB, USABLE_FILE_MB
from V$ASM_DISKGROUP;

    GROUP# NAME           STATE             TOTAL_MB    FREE_MB
REQ_MIRR_FREE_MB USABLE_FILE_MB
---------- -------------- --------------- ---------- ----------
---------------- --------------
         1 DATA           MOUNTED              20480      20374
5120           7627

I was hoping to see REQ_MIRR_FREE_MB of zero because I have a DG that
contains two failure groups with each group contains two disks. I was
also expecting to see 10GB for the USABLE_FILE_MB.

Can someone please clarify how two interpret these stats.

Thanks
Amir

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