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after DROP USER <user_name> CASCADE - volumes not being freed up

francois_keen
Participant
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302

Hello HANA community,

We've just achieved an upgrade/migration from BW 7.3 on Oracle to 7.4 on Hana 73 using SUM DMO.

We're about to redo another upgrade in order to refine our upgrade/migration steps, so I dropped the BW schema using this command:

drop user SAPBP2 cascade;

Statement 'drop user SAPBP2 cascade'

successfully executed in 12:56.125 minutes  (server processing time: 12:56.113 minutes) - Rows Affected: 0

I'm not sure why the output shows Rows Affected: 0 but the user and its schema are definitely gone from the Catalog and Security folders in the Studio.

My problem is that the Volumes size and Memory usage didn't seem to have reduced at all. I restarted HDB but it still shows the same volume usage for my index servers...

It doesn't look like there should be a special trick in the drop command, so i'm not sure to understand why at least the volume usage didn't go down,

Any idea why?

Thanks for your help.

best regards

Francois

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lbreddemann
Active Contributor
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Hi Francois

Why do you expect that we shrink the data volumes when you delete data content?

And why would we de-allocate memory from the OS?

Both are very costly operations and it is very likely that we will need the file and the memory again.

Instead, SAP HANA knows which which parts of the data volume files and which memory areas are usable for new data. It has its own memory management and file handling built-in.

If you want to check what's actually used and what's available for use, check with the SAP HANA tools.

Detailed information can be found in the Admin guide plus there is a comprehensive document on SAP HANA memory management available on SAPHANA.COM.

- Lars

francois_keen
Participant
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Hi Lars

Thanks for the clarification.

My second upgrade/migration went fine.

All good!

Cheers

Francois