Configuring the guestapps.conf file

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To help ensure that backup operations will be successful for Db2®, MongoDB, and SAP HANA databases, create the guestapps.conf file in /etc/ and adjust the parameters by using the minimum acceptable snapshot size that allows to complete the backup without an error.

Before you begin

Ensure that you have created the /etc/guestapps.conf file which doesn’t exist by default.
Ensure that the space requirements for Db2, MongoDB, and SAP HANA are met. For more information, see Space requirements for Db2 protection, Space prerequisites for MongoDB protection, and Space requirements for SAP HANA protection.
Ensure that you determined the minimum acceptable snapshot size. For instructions, see Determining the minimum acceptable snapshot size.

About this task

The procedure for configuring the parameters in the guestapps.conf file is the same for Db2, MongoDB, and SAP HANA.

To understand how to allocate space in a volume group, consider the following example.

Assume that you have a volume group with total space capacity of 20 GB. The default value indicates that the minimum free space allocation is 2 GB (10%), and the maximum allocation is 5 GB (25%). During an inventory, the agent checks that the volume group has at least 2 GB of free space. Otherwise, an error message is displayed. If the free space is less than 5 GB, all available free space will be used to create the snapshot.

vg space allocation — Figure 1. Space allocation in a volume group

Based on the previous example, you would configure the guestapps.conf file.

The following figures show the parameters in the guestapps.conf file for different databases. The shown values represent the defaults that are applied in the absence of the file.

Db2:

[DEFAULT]

Db2MinimumFreespaceInPercent = 10
Db2MaximumAllocationInPercent = 25
Db2MinimumSnapshotVolumeSize = 50

MongoDB:

[DEFAULT]
MongoMinimumFreespaceInPercent = 10
Db2MaximumAllocationInPercent = 25
Db2MinimumSnapshotVolumeSize = 50

SAP HANA:

[DEFAULT]
HANAMinimumFreespaceInPercent = 10
HANAMaximumAllocationInPercent = 25
HANAMinimumSnapshotVolumeSize = 50

Tip: When this logic is applied to thin-provisioned source volumes, the actual size is considered rather than the virtual size.

Procedure

To configure the guestapps.conf file, complete the following steps:

Remember: This procedure is an example for configuring the parameters for Db2.

The Db2MinimumFreespaceInPercent parameter, which specifies the minimum percentage of free space in a volume group that must be available to create snapshots. The agent will not start a backup operation if the percentage of free space in a volume group is less than this value.

To help ensure that the backup operation can take place successfully, you must add free space to the volume.
Calculate the value of the Db2MaximumAllocationInPercent parameter by using the following formula:
```
snapshot_size / sourceLV_size * 100
```
where snapshot_size is the size of the snapshot that you detected and sourceLV_size is the size of the source logical volume.
When backing up several logical volumes, use the maximum of all calculated Db2MaximumAllocationInPercent values.
Configure the parameters in /etc/guestapps.conf file and save the file.

What to do next

Repeat the backup operation. If issues recur, increase the Db2MaximumAllocationInPercent and optionally Db2MinimumSnapshotVolumeSize in the guestapps.conf file.

The Db2MinimumSnapshotVolumeSize parameter sets a lower limit for the snapshot size in absolute units (MB). In some cases, you might have to increase the Db2MinimumSnapshotVolumeSize in the guestapps.conf file for a successful backup. Then, repeat the backup operation.