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Data protection designed to help meet SAP HANA backup and recovery windows

StorageExperts

In my customer engagements on SAP HANA storage backup strategy and architectures, I often encounter questions on how to meet specific backup and recovery requirements in an SAP HANA context. So well worth the time to share my perspective here on HPE StoreOnce data protection. 

SAP HANA uses in-memory technology, but requires a backup solution to protect against failures in tData Protection SAP HANA  backup windows_Blog.jpghe persistent layer, or to recover a database to an earlier point in time. Backups provide a low-cost protection solution, but in general do not guarantee a zero-loss protection, or Recovery Period Objective (RPO).  By RPO, we mean the maximal permissible period of time during which operational data may be lost without the ability to recover. When data needs to be recovered and logs need to be replayed from backup media, we want to keep the recovery window as low as possible.

Just how low is a realistic RTO?

To make sure we are on the same page, we define Recovery Time Objective (RTO) as the maximal permissible time it takes to recover the system, so that its operations can resume. How low a realistic RTO can go depends on the backup methodology being used.

Online Backup and Recovery through SAP HANA backing up the complete data set

SAP HANA up until SPS11 uses a single stream online backup, using the backint API. This means that using a single 10GbE connection, or single 8g FC link, we can achieve a maximum single stream backup throughput of 300-400MB/s. Tuning can be applied to the backup stream by using deduplication, or disabling backup HPE StoreOnce Catalyst compression and Catalyst checksum algorithms. Considerable backup performance enhancements are available with SPS11, where up to 32 backups streams can be used to transfer the data to the backup appliance or tape media.

Recovery speeds are similarly restricted by the single stream of data that restores data and log volumes from the backup media onto the persistence layer. A recovery speed of 150-200MB/s is not uncommon. Recovery speed can be similarly increased by disabling backup Catalyst compression and Catalyst checksum algorithms.

Backup speeds used for sizing purposes range between 0.5GB to 1TB/h for online data backup. Using a single stream backup, sizing the backup appliance is largely based on capacity and retention. Backup and recovery performance remains within the same range across all StoreOnce models as the appliance is typically not the limiting factor. A lower RTO for online backup can only be achieved by increasing the backup and recovery throughput across the network or FC infrastructure.

Snapshot Backup & Recovery through SAP HANA “prepare database for snapshot” mode

The SAP HANA database allows the creation of an internal snapshot, which is a point-in-time copy of the save-point, in a consistent state. Snapshots can be replicated in the form of full data backups, which can then again be used to restore a database to a specific point in time. In addition to data backups and snapshots, smaller periodic log backups ensure the ability to recover from fatal storage faults with minimal loss of data.

An external storage snapshot can be created to guarantee a database crash consistent copy of the parent data volume. Storage snapshots only make a copy of the data payload, not the logs. As such, recovery from the data snapshot will be faster than from online backups, but additional time has to be incorporated for the log replay from online backup media. Storage snapshot backups also do not offer a consistency check in the SAP HANA database on block level today. Storage snapshots are not integrated with backint today, so do not have access to API-based database integrations like Multitenant Database Containers (MDC), single-tenant Backup & Recovery or granular incremental/differential Backup and Recovery.

An external storage snapshot backup creates a crash consistent copy of the database data volume. An application consistent copy can be created if the SAP HANA database is prepared for snapshot backup (‘BACKUP DATA CREATE SNAPSHOT), prior to taking the storage snapshot. The storage snapshot creation is confirmed back to the SAP HANA Studio catalog database as successful or failed by using the snapshot WWID as Extended Backup ID.

While a SAP HANA database snapshot is being created, no complete/online data backup can be performed. If an internal snapshot already exists when a backup is started, the backup will not be executed and an error will be presented. Multiple internal named SAP HANA database snapshots are planned for the future.

Storage snapshots offer an alternative backup method from keeping the SAP HANA database in online backup mode for an extensive period of time. They also offer much more flexibility in recovery options. Using the HPE StoreOnce Recovery Manager Central (RMC), a Snapshot Set will create a local storage snapshot data volume copy on HPE 3PAR StoreServ disk. Then Express Protect can be used (via REST API scripts) to create another copy using multiple block-based streams onto a StoreOnce System. Recovery can be done from the Snapshot Set onto the original data volume parent disk, a new data volume copy can be created onto the same HPE 3PAR StoreServ array, or a new data volume copy can be created onto a new HPE 3PAR StoreServ array, connected to the RMC instance.

Recovery Manager Central creates an initial full copy on the StoreOnce System. All subsequent backup operations create synthetic full copies leveraging the 3PAR snapshot differencing technology. Recovery Manager Central serves as an easy to use, automated snapshot management platform, which can be used with or without a StoreOnce System. When using Recovery Manager Central with a StoreOnce System, we can also replicate snapshots without rehydrating between multiple StoreOnce appliances, allowing for distributed, efficient data protection.

Recommendation for achieving the best backup and recovery

With the above understanding, achieving an RTO of 4 hours for a 12TB database through online backup and recovery for instance may be quite challenging.

For any SAP HANA scale-up (Business Warehouse or Suite-on-HANA) database larger than 4TB, we recommend using a combination of weekly full online backups, with daily storage snapshot backups. A scale-out Business Warehouse database can be backed up using online backups, while a Suite-on-HANA database requires the use of storage snapshots for backup.

Stay tuned for future blog topics on flat backup, optimizing deduplication ratios and other data protection topics

Learn more

T-sap-award_2015__153x115--C-tcm245-2043085--CT-tcm245-1237012-32.jpg

HPE Reference Architecture for SAP HANA backup and recovery using the HPE StoreOnce Plug-in for SAP HANA

HPE StoreOnce Recovery Manager Central

More on HPE Storage data protection solutions for SAP HANA

 

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Meet Around the Storage Block blogger Inge De Maere, WW SAP HANA SME, UDU ATC, HPE Storage. Expect to hear more from our technical marketing team.

 

 

 

xxx

About the Author

StorageExperts

Our team of Hewlett Packard Enterprise storage experts helps you to dive deep into relevant infrastructure topics.

Comments
Rob Miller

Great article, really informative and easy to understand. I will be certain to try this out, hopefully it will be the end to a problem for me. I will let you know how I go!

StorageExperts

Thanks, Rob, for your feedback. Let us know if your problem is solved!

-your ATSB editor

Fanny Osorio

Great blog Inge! Very informational....

One quick question: is Recovery Manager Central an HPE SW product that requires additional licensing? Thanks!

 

StorageExperts

Thank you, Fanny,  for your comment.

 Yes, RMC requires additional licensing. RMC with a basic license can protect any application running on any 3PAR StoreServ array using crash-consistent snapshots. RMC with an application-specific license for a specific 3PAR StoreServ array can ensure protection either through crash-consistent or application-consistent snapshots.

You might find this blog an interesting read: 

Data Protection That Keeps Downtime Down for Apps on Flash Storage

Best,

-Ashwin Shetty, BURA team, HPE Storage

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