Re: ASM adding disk with different sector size

What Raj said, but in particular pay attention to your redo logs, particularly if using Data Guard.

(It used to not be possible even to migrate to storage with a different sector size, back in the V11 time-frame I think.)

Regards,

John Thomas

On Thu, 14 Oct 2021 at 22:30, Sandra Becker <sbecker6925_at_gmail.com> wrote:

> Thanks everyone for your input. Until it was mentioned, I didn't realize
> I forgot to mention the OS and oracle versions. The OS is RHEL 5.11 (I
> know, it's old, but I can't get approval to upgrade yet) and the database
> is EE 12.1.0.2. I'm told the new storage will be Netapp. Our storage team
> was pushing us to just use NFS mounted disk instead of ASM. I flatly
> refused since this cluster is the development cluster before things go to
> test and then production. Our policy has always been develop on
> "production-like" systems to mitigate issues due to differences in the
> configurations. We do not have Oracle support, so I can't open an SR with
> them. I did open a ticket with Rimini Street, our current support vendor,
> and will keep them in the loop for what we plan to do.
>
> I knew you couldn't mix sector sizes in the same disk group, but didn't
> know if ASM would support two different disk groups with different sector
> sizes for the same database. I have no concern with getting everything on
> the 4k sectors, just wondering what would be the best way to do it while
> minimizing downtime. It's not a production system, so downtime isn't as
> big a concern, but some dev teams are just ramping up for a major critical
> project that upper management is monitoring closely.
>
> Thanks again,
>
> Sandy
>
> On Thu, Oct 14, 2021 at 3:48 AM Martin Klier - Performing Databases GmbH <
> martin.klier_at_performing-db.com> wrote:
>
>> Sandra,
>>
>> on top of what Raj wrote - there can as well be dependencies coming from
>> the use of the disk group.
>>
>> For example, Redo Block size is always directly derived from the disk's
>> LBA size. If you migrate to another one, you may run into another subset of
>> difficulties.
>>
>> HTH
>> Martin
>>
>> --
>> Martin Klier // Performing Databases GmbH
>> Managing Partner // Senior DB Consultant
>> Oracle ACE Director
>>
>> martin.klier_at_performing-db.com // https://www.performing-databases.com
>>
>>
>>
>> ------------------------------
>>
>> *Von: *"Rajesh Aialavajjala" <r.aialavajjala_at_gmail.com>
>> *An: *sbecker6925_at_gmail.com
>> *CC: *"Oracle-L Freelists" <oracle-l_at_freelists.org>
>> *Gesendet: *Mittwoch, 13. Oktober 2021 02:16:28
>> *Betreff: *Re: ASM adding disk with different sector size
>>
>> Sandra,
>> To the best of my understanding - ASM does not permit mixed sector sizes
>> in a single disk group - so I presume that rules out the use of the
>> 'removing the old disks and rebalance as we go'
>>
>> You didn't include the version of grid infrastructure/ASM that your
>> environment is running ... but this was not allowed in 12c...
>>
>> 12c -->
>> https://docs.oracle.com/database/121/OSTMG/GUID-8B656725-D347-4166-8775-1070B6C4D580.htm#OSTMG10203
>>
>> In 19c and higher - there's the concept of logical_sector_sizes and
>> physical_sector_sizes but I am unsure of how that would fit into your
>> migration scenario...
>>
>>
>> https://docs.oracle.com/en/database/oracle/oracle-database/21/ostmg/create-diskgroups.html#GUID-8B656725-D347-4166-8775-1070B6C4D580
>>
>> Additions, comments, corrections welcome (and I will gladly defer to the
>> wiser folks in this group)
>>
>> Thanks,
>>
>> --Rajesh
>>
>>
>>
>> On Tue, Oct 12, 2021 at 2:16 PM Sandra Becker <sbecker6925_at_gmail.com>
>> wrote:
>>
>>> We need to move some databases off of their current storage, which is
>>> old and no longer supported. The new disk will have a different sector
>>> size. Can we create a new diskgroup for the new storage and use it along
>>> with the old storage? If possible, can we do the balancing and then start
>>> removing the old disks and rebalance as we go? I'm not very familiar with
>>> ASM, so would appreciate some guidance or pointing me to an appropriate
>>> document. I've been doing some google searches, but still not sure we can
>>> move the databases in this manner.
>>>
>>> Thank you,
>>>
>>> --
>>> Sandy B.
>>>
>>>
>>
>
> --
> Sandy B.
>
>

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