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

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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