Backup sluggishness due to MVCC garbage collection blocked

[Former Member]

Hi All,

Wanted to share with all that we had a issue where the backups were taking a long time due to MVCC garbage collection being blocked.

We are on revision on 82.

2122316 - MVCC Garbage Collection Is Blocked During Data Backup When
Auditing Is Enabled

So all please check your backup performance if you are on this revision.

Wanted to share.

[Former Member · Accepted solution]

SAP Note 2169283 (FAQ: SAP HANA Garbage Collection) may be helpful for you to get an overview about potential issues in the area of garbage collection.

[Former Member · Accepted solution]

But martin, SAP development said that during the audit on phase and backup running at the same time lots of MVCC versions which caused the problem. What do you suggest?

[Former Member · Accepted solution]

As a workaround, schedule data backup to a time slot when there is less load on the system or disable auditing.

The issue will be fixed in SAP HANA revision 93 and 85.04 and later.

[Former Member · Accepted solution]

Martin,

Thanks for that . But as you know its not easy to get a quiet time when you think from business perspective.

But what i wanted to know is that during the backup and audit on are there lot of MVCC versions getting created?

[Former Member · Accepted solution]

Yes, that's the risk.

[Former Member · Accepted solution]

So delta merge and MVCC merging would be two different things right then?

[Former Member · Accepted solution]

Yes, delta merges and column store garbage collection are two different activities - although both may overlap to a certain extent.

[Former Member · Accepted solution]

So during the audit on and backup process the garbage collection doesnt happen right martin.

Danke.

[Former Member · Accepted solution]

There is a risk that it doesn't happen because of open transactions.

[Former Member]

I have seen similar issue in revision 74. Planning to upgrade our revision soon  to eliminate the issue.