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6 Replies Latest reply: Aug 23, 2012 12:44 AM by BillyVerreynne RSS

Adding Space

user12006733 Newbie
Currently Being Moderated
If a Datagroup DATA_DG has been allocated 5GB and is full. How do we add and allocate more space to a DataGroup.
  • 1. Re: Adding Space
    KuljeetPalSingh Guru
    Currently Being Moderated
    add another disk in this disk group.
  • 2. Re: Adding Space
    BillyVerreynne Oracle ACE
    Currently Being Moderated
    user12006733 wrote:
    If a Datagroup DATA_DG has been allocated 5GB and is full. How do we add and allocate more space to a DataGroup.
    There is no such thing as a +"data group+" in Oracle.

    ASM uses disks and diskgroups. Oracle uses tabespaces and datafiles (and also extents, segments and data blocks).

    If a diskgroup is full, you can either create a new diskgroup as storage container, or you can add more disks to an existing diskgroup.

    The adding disks to a diskgroup is not straightforward. Disks in a diskgroup is striped. Thus the new disk added, will become part of the striped set - and this requires what ASM calls a rebalance to occur, in order to make that new disk part of the stripe. If the disk is normal redundancy (mirrored) adding a single disk will only increase space for one part of the mirror. Another disk needs to be added to grow both mirror sets the same size.

    5GB diskgroup is also questionable. Disks are typically 512GB and larger. Partitioning disks and creating diskgroups on partitions, is not recommended.

    Make sure you have read the ASM documentation and understand how to use ASM to manage storage effectively and optimally.
  • 3. Re: Adding Space
    user12006733 Newbie
    Currently Being Moderated
    Sorry it was a typo...I meant diskgroups. The 5gb Diskgroup was just for an example.

    Thanks
  • 4. Re: Adding Space
    BillyVerreynne Oracle ACE
    Currently Being Moderated
    So is this full diskgroup created as external, normal or high redundancy?

    How many disks are currently in the diskgroup, and what are the sizes of these disks?
  • 5. Re: Adding Space
    user12006733 Newbie
    Currently Being Moderated
    I created a OCR_DG diskgroup as normal and DATA_DG as external.

    DATA_DG is the one which could be full and has around 50GB with 5 disks.
  • 6. Re: Adding Space
    BillyVerreynne Oracle ACE
    Currently Being Moderated
    In that case you can add a single disk to DATA_DG diskgroup to add additional space. A rebalance operation will result (see v$asm_operation) to restripe the data.

    The new disk should be of an equivalent size (and of performance) than those existing disks in the diskgroup.

    However, 5 disks in a 50Gb diskgroup does not sound very healthy to me. 10Gb disks used? Are these real disks, partitions, LUNs or virtualised? And are they on the same I/O channel?

    ASM cannot fix underlying issues with a poorly designed or configured storage system.

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