Oracle DB server allocate huge much space on hpe simplivity after ORACLE RMAN works

[Mustafa23]

Hello!

I wanted to do disk optimisation on my oraclae db vm server on simplivity. It was almost 1,7 TB of size including RMAN backups in RMAN directory. 

I applied sdelete and size decrased to 1.2 TB. During night RMAN works and my VM size increased by 200 GB data and size was 1.4 TB.

 My backup policy is, It has 3 daily, 6 1-hour, 6 6-hour, 3 10-minutes (totally 18.). My datastore is almost  %85 size.

I delete all simplivity backups to find issue if this problem from backups for capacity issues. After deleting all backups I gained space almost half of my datastore size 

RMAN works every night. Simplivity backups uniqe size seems 2-3 GB. Hovewer when I delete some backups, huge amount (400-500GB) of space returned on datastore. 

 What it gets interesting is when I started deleting those backups and monitor how much free space.  I'm gaining almost half of the size of my all datastore. (18 TB bfore, 10 TB after) terabytes on each host where this VM's primary and secondary copy were located.

Has anyone experienced something like that? Am I missing someting? I dont have much oracle experience. Could there be any logical explanation to such behavior? Sorry for ant inconvenience. Any help really appreciated.

[Aditya_A]

Hi,
Oracle database backups indeed have more unique data uploaded for the new backups than other VMs purely because of the way databases work.
I'd recommend you to generate a backup report using the HPE SimpliVity plugin or if you are using InfoSight, please have a check on the Oracle VM data and it will show the data usage trend which will provide a good insight.

Moreover, I'd recommend you to go throgh this blog which talks about how is VM data managed in HPE SimpliVity cluster: https://community.hpe.com/t5/around-the-storage-block/how-vm-data-is-managed-within-an-hpe-simplivity-cluster-part-1/ba-p/7019102
It's a 5 part blog, please do read all of them.

[Mustafa23]

Hi,

Thank you very much. for your information.Here storage efficiency (8.9:1), backup report of oracle Server and total number of backup..  My efficiency rate is very low.  Am I missing something? or is it normal? Is there any suggeston about oracle usage in simplivity?

| Name                                          | Bytes    | Local   | Offnode | Heuristic | Backup                   |

                                               | Written  | Size    | Size    |           | Time                     |

+-----------------------------------------------+----------+---------+---------+-----------+--------------------------+

|THIS IS MY ORACLE SERVER (datastoreX)            |          |         |         |           |                          |

+-----------------------------------------------+----------+---------+---------+-----------+--------------------------+

| 2023-10-04T00:00:00+03:00                     |   1.51TB |  1.51TB |         |  187.91GB |  |

| 2023-10-05T00:00:00+03:00                     | 430.32GB |  1.52TB |         |   52.40GB | |

| 2023-10-05T18:03:00+03:00                     | 400.74GB |  1.53TB |         |   48.80GB |  |

| 2023-10-06T00:03:00+03:00                     |  23.89GB |  1.53TB |         |    2.91GB |  |

| 2023-10-06T00:07:00+03:00                     | 553.62MB |  1.53TB |         |   67.41MB |  |

| 2023-10-06T06:03:00+03:00                     | 307.64GB |  1.53TB |         |   37.46GB |  |

| 2023-10-06T10:39:00+03:00                     |  76.49GB |  1.55TB |         |    9.31GB | F |

| 2023-10-06T11:09:00+03:00                     |   3.26GB |  1.55TB |         |  406.62MB |  |

| 2023-10-06T11:39:00+03:00                     |   3.74GB |  1.55TB |         |  466.38MB |  |

| 2023-10-06T12:03:00+03:00                     |   4.28GB |  1.55TB |         |  533.08MB |  |

| 2023-10-06T12:09:00+03:00                     | 639.19MB |  1.55TB |         |   77.83MB |  |

| 2023-10-06T12:39:00+03:00                     |   6.04GB |  1.55TB |         |  753.50MB |  |

| 2023-10-06T13:09:00+03:00                     |   3.60GB |  1.55TB |         |  449.04MB |  |

| 2023-10-06T13:39:00+03:00                     |   1.71GB |  1.55TB |         |  212.70MB |  |

| 2023-10-06T14:09:00+03:00                     |   3.30GB |  1.55TB |         |  411.61MB |  |

| 2023-10-06T14:39:00+03:00                     |   1.59GB |  1.55TB |         |  198.37MB |  |

| 2023-10-06T15:09:00+03:00                     |   2.52GB |  1.55TB |         |  314.28MB |  |

| 2023-10-06T15:39:01+03:00                     |   1.48GB |  1.55TB |         |  184.68MB |  |

| 2023-10-06T16:09:00+03:00                     |   2.39GB |  1.55TB |         |  298.07MB |  |

+-----------------------------------------------+----------+---------+---------+-----------+--------------------------+

| VM Total Backups: 19 of 19                    |   2.75TB | 29.32TB |      0B |  343.07GB |                          |

| = local 19 + offnode 0, unknown 0             |          |         |         |           |                          |

For node OmniStac in cluster 
- Total Node Data: 66.82TB = Data: 10.89TB + Local backup: 55.93TB + Remote backup: 0B
- Compressed: 8.14TB, Uncompressed: 11.56TB
- Comp ratio: 0.70382
- Dedup ratio: 0.17304
- Total number of backups: 67
- Number of backups shown: 67 = Local 67 + Offnode 0, unknown 3
- Total backup bytes: 50.03TB = local 50.03TB + offnode 0B
- Gross heuristic estimate: 1.46TB

[Aditya_A]

DB VMs do tend to have lower compression and dedup ratio although I will recommend having this checked once by opening a support case. Support engineer can diagnose if there's any issue which may be causing lower ratios.

[gustenar]

@Mustafa23 

I wanted to share this document with you: 

HPE Reference Architecture for Oracle Database 12c on HPE SimpliVity 380 Gen10

It's a bit outdated but may still be useful. 

Also, pay attention to the retention periods of your SimpliVity backups. If you have multiple backups running during the day and keeping them for extended periods of time it will contribute to the high capacity utilization. 

[yazmeh]

Hello!

It seems like you are facing an unusual situation with your Oracle DB VM server on HPE SimpliVity. The fluctuating storage size after RMAN (Oracle Recovery Manager) backups can be perplexing. While I can't provide a definitive solution without a detailed analysis, I can offer some insights.

In Oracle environments, especially with frequent backups and data changes, storage behavior can be complex. Here are a few things you might consider:

1. RMAN Incremental Backups: RMAN's incremental backups only back up the blocks that have changed since the last backup. This method can sometimes lead to unexpected data growth due to how Oracle manages these incremental changes.

2. Data Deduplication: SimpliVity employs deduplication techniques to optimize storage. However, the effectiveness of deduplication can vary based on the type of data being stored. Large databases with high update rates might not deduplicate as efficiently.

3. Backup Retention Policy: Your backup retention policy, especially with the frequent backups, might lead to significant storage utilization. Deleting backups should free up space, but the immediate return of such a large amount of space could be due to how SimpliVity handles data deduplication and compaction after the deletion.

4. Space Reclamation: SimpliVity and other storage systems often perform space reclamation tasks in the background, which might explain the sudden increase in available space after backup deletion.

If the issue persists, it might be beneficial to consult Oracle support or HPE SimpliVity experts for a more in-depth analysis tailored to your specific setup. They can provide detailed insights into the storage behavior and help you optimize your backup strategy for efficient space utilization.