Tune Dedup VVs to a different CPG

[_SANAdmin]

#Background

A 7450c system with 192 drives.

- Disks 0-95 form a CPG (let us say CPG1)

- Disks 96-191 form another CPG (CPG2)

#Plan

Migrate all the volumes from the CPG2 to CPG1 and remove the drives 96-191 from the system

#Challenges

CPG2 has considerable number of TDVVs. System returns "Error: Dedup volume must be tuned to the same cpg" when I attempt to tune a TDVV from CPG2 to CPG1. 

#Questions

1. Should we convert the TDVV volumes to TPVV when we tune them to CPG1 to avoid the above mentioned error? Is there any other workaround? 

2. Once I migrate all the volumes from the CPG2 to CPG1, I plan to delete the CPG2 before engaging HPE to remove the drives from the system. Is there a procedure I could follow and prepare the drives for removal? 

If I am missing something, please let me know. 

[veeyarvi · Accepted solution]

Hi SANAdmin,

I am not sure about the version of Inform OS you are running on. Also not sure about the command used to tune.

From CLI, we can try the below command if the Inform OS version is below 3.3.1 MU2 need to specify '-tdvv' along with the tunevv

“tunevv usr_cpg <New CPG name> -tdvv <VV Name>" 

Regards,
Veeyarvi

[_SANAdmin]

Thanks Veeyarvi. System InForm OS version is 3.2.2 (MU6). If I understand this correctly, I must specify "-tdvv" when migrating a TDVV from one CPG to another. Is that correct? 

That's not the case with TPVVs. I can migrate TPVVs between CPGs without specifying "-tpvv" option. 

Is that because TDVV migration usually results in a new volume creation at the target CPG and old ones get deleted after successful migration? 

[veeyarvi]

Hi SANAdmin,

Yes, please try specifying the -tdvv option with the tune command (For 322 MU6, -tpvv can be used as well.). 

And I assume, the new CPG is also SSD tier.

Regards,

Veeyarvi

[_SANAdmin]

Thanks Veeyarvi. Yes, the target CPG is also an SSD tier. I need to perform this work under a proper change control. Will let you know the outcome. 

Will you be able to help me with another question?

Once I migrate all the volumes from the CPG2 to CPG1, I plan to delete the CPG2 before engaging HPE to remove the drives from the system. Is there a procedure I could follow and prepare the drives for removal? 

[veeyarvi]

Hi SANAdmin,

You need to vacate the drives before removing them. Also, some of the admin lds need to be removed from these pds but you might be needing HPE support for the same. So my suggestion is to engage HPE after the CPG migration.

(Also, for the tuning issue also, if you still unable to tune VVs to new CPG, log a case with the support. There may be some underlying issues which needs to be fixed for the tuning to complete.)

Regards, 
Veeyarvi

[_SANAdmin]

Thank you, Veeyarvi.

[_SANAdmin]

@veeyarvi 

Hi Veeyarvi,

I have managed to migrate a dummy TDVV volume between SSD CPGs using the following command. Thanks for it. Can you confirm if this migration is transparent to OS and does not trigger any unnecessary issues? I am planning to migrate Production TDVVs and it is important to make sure this is a non-disruptive work. 

tunevv usr_cpg <targetCPG> -tdvv <VolumeName>

Thanks 

[veeyarvi]

Hi _SANAdmin,

The activity is online.  But, please keep in mind that, there will be an increase in backend IOPS when the movement happens. Please schedule them in lesser load timings and preferrably one at a time.

Veeyaarvi

[_SANAdmin]

@veeyarvi 

Thank you. Yes, I've scheduled this work on Saturday 2nd July - and yes, one volume at a time. Will keep you updated.