Re: ASM Question/Suggestions - moving from 10TB devices to 20TB devices and diskgroup move

Ok, so I think I'm following and that makes sense.

In a nutshell it would be add all the new 20T devices *AND* drop the existing 10T devices in the same command so that the rebalance only rebalances to the 20T devices?

Is that the theory/idea?

That would definitely prevent the need to use rman to move the datafiles or anything.

Chris

On Wed, Sep 8, 2021 at 10:09 AM Mikhail Velikikh <mvelikikh_at_gmail.com> wrote:

> Hi,
>
> I know ASM devices should be the same size when you rebalance.
>>
>
> If it is an EXTERNAL redundancy disk group, then you can have a disk of
> different size there.
> 12c ASM: Unable To Add New Disks With Dissimilar Size To 12.1.0.2 ASM
> Diskgroups (Normal or High Redundancy) Due To ORA-15410 (New 12c ASM
> Enhancement Validation/Constraint) (Doc ID 1938950.1)
> <https://support.oracle.com/rs?type=doc&id=1938950.1>
> Although it is not a best practice, it can be used during such migrations.
>
> Is that the *only* option here? Anyone have additional
>> suggestions/thoughts?
>>
>
> 1. You can resize the existing disks online, then drop the disks you don't
> need.
>
> https://docs.oracle.com/en/database/oracle/oracle-database/19/ostmg/alter-diskgroups.html#GUID-6AEFFA72-7BDC-4AA8-8667-8417AAF3DAC8
> It didn't work for me two years ago with AFD. I haven't encountered the
> same issue with ASMlib or without any Oracle drivers.
> If you don't use AFD, ignore notes below:
> Cannot resize ASM Disk using ASM Filter Driver(AFD) online (Doc ID
> 2099164.1)
> ASM not displaying resized disk size in AFD configuration (Doc ID
> 2263094.1)
> Bug 29893839 - ASM CRASHES WHEN RUNNING AFD_REFRESH AFTER THE LUN RESIZE
> AT OS LAYER (Doc ID 29893839.8)
>
> 2. You can provision new 20TB LUNs and DROP/ADD disk in one ALTER
> DISKGROUP command. ASM automatically rebalances data.
>
> https://docs.oracle.com/en/database/oracle/oracle-database/19/ostmg/alter-diskgroups.html#GUID-14E48E96-F5D6-4F41-A8E4-B535CBD3CAE5
>
> Best regards,
> Mikhail Velikikh
>
>
>
> On Wed, 8 Sept 2021 at 14:46, Chris Taylor <
> christopherdtaylor1994_at_gmail.com> wrote:
>
>> List,
>>
>> We have a need to restructure our underlying ASM devices to 20T from 10T
>> to reduce the number of luns assigned to a host.
>>
>> The Total DiskGroup SIze is 163840.00 GB (~ 160 TB) made up of 10TB
>> devices. (16 Devices)
>>
>> Our storage admins would like to move these to 20T devices and halve the
>> number of physical devices presented.
>>
>> I know ASM devices should be the same size when you rebalance.
>>
>> I know *one* option is to add the 8 20T devices as candidates and create
>> a new diskgroup and move the data to the new diskgroup and then drop the
>> old 10T devices from ASM.
>>
>> Is that the *only* option here? Anyone have additional
>> suggestions/thoughts?
>>
>> Chris
>>
>>

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