HANA Backup Issue

Symptom

The performance duration of a SAP HANA DB backup with backint takes extremely long time until reach successful the end.
In the trace files, there are no issues or error to found.

Environment

SAP HANA DB 1.0
SAP HANA DB 2.0

Reproducing the Issue

Long backup duration time occurs and following default configuration values was in use:

data_backup_buffer_size from 512
parallel_data_backup_backint_channels from 1

Resolution

In different issues with long backup durations, following changes in the parameters does help to get a shorter duration time of the backup. 

data_backup_buffer_size from 1536
parallel_data_backup_backint_channels from 3 


Please read careful:

A backup in HANA is done via two twin buffers and each of them have default 512 MB. Using parallel asynchronous threads, the data blocks from the Index Server will be read in one of this two buffers, while the other, which is already filled, is everted to the destination medium (file or backint). Once this buffer is free, it is new filled and the other will be everted. The larger the buffer is, the more data blocks can be read in parallel, but this does not scale arbitrarily. Depending on the HW/IO will sometime saturate. 

The channel parameter is only for Backint and the reason why in different issues the performance has improved significantly. Now the data is read not only in two buffers, it reads in many as channel plus one. With Backint, the evasion is the problem, which is why we have several channels for writing and then it works too with the Backint Performance. The number of channels depends on the customer's infrastructure, and we can’t easily set more than one. Incidentally, a buffer is created per channel. At 512 MB per channel per service, it quickly comes in several GB. Then an increase in the buffer sizes should not be made arbitrarily.

Please test this values of the parameter on your test system first and see, if this will help in your special long backup duration issue.