Diagnosing an ASM space issue for a primary and a standby database instance with exte
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Thread: Diagnosing an ASM space issue for a primary and a standby database instance with exte

  1. #1
    Join Date
    Aug 2014
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    2

    Diagnosing an ASM space issue for a primary and a standby database instance with exte

    I've received an alert from Enterprise manager saying "Disk Group DATA_SID requires re-balance because at least one disk
    is low on space". This is a staging environment, set up with external redundancy. My colleague who I would go to with this question is unavailable, so this is a learning opportunity
    for me. So far Google and Oracle documentation have provided lots of information, but nothing that answers my questions.

    I've run the following query on both the primary and standby databases ASM instances:
    select name, disk_number, sector_size,os_mb, total_mb, free_mb, redundancy from v$asm_disk;

    On the primary I get 4810M Free space and 18431M Total Space
    on the standby I get 1248M Free space and 18431M Total Space -- this is the one that complained via OEM

    When I run the following query in the database instance:
    select sum(bytes)/1024/1024 MB from dba_segments;

    I get 3736.75M as a result.

    My question is:
    1. Will OEM's suggestion to rebalance the disk actually help in this situation since the instance is set up with external redundancy?
    2. If I've got 18G of space and only 3.7G of data, why is OEM complaining?
    3. How can I reclaim what I presume is allocated but unused space in my problem disk group?
    4. How can I determine what extra data the standby has that the primary doesn't since both have the same total space allocation, but different amounts of free space?

    Thanks in advance.
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  2. #2
    Join Date
    Jul 2002
    Location
    Lake Worth, FL
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    1,483

    Cool

    Quote Originally Posted by choffmann View Post
    I've received an alert from Enterprise manager saying "Disk Group DATA_SID requires re-balance because at least one disk is low on space".
    On the primary I get 4810M Free space and 18431M Total Space
    on the standby I get 1248M Free space and 18431M Total Space -- this is the one that complained via OEM

    . . .
    My question is:
    1. Will OEM's suggestion to rebalance the disk actually help in this situation since the instance is set up with external redundancy?
    2. If I've got 18G of space and only 3.7G of data, why is OEM complaining?
    3. How can I reclaim what I presume is allocated but unused space in my problem disk group?
    4. How can I determine what extra data the standby has that the primary doesn't since both have the same total space allocation, but different amounts of free space?

    Thanks in advance.
    1) That is only a warning, ASM will automatically re-balance the disks
    2) ASM will distribute the data evenly between all disk
    3) You don't unless you remove some files.
    4) In OEM go to Administration->ASM Home and look at the contents (files) on the disk group.
    "The person who says it cannot be done should not interrupt the person doing it." --Chinese Proverb
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  3. #3
    Join Date
    Aug 2014
    Posts
    2
    Thank you, that was exactly what I needed to get to the root of the problem. The major space consumer turned out to be the undo tablespace.
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