Manage the SAP HANA Fast Restart configuration

This document describes how to enable the SAP HANA Fast Restart option for an SAP HANA workload. This guide also describes how to modify the SAP HANA Fast Restart configuration when you resize the Compute Engine instances that host the SAP HANA workload.

The SAP HANA Fast Restart option reduces the restart time in the event that SAP HANA terminates while the operating system remains running. Google Cloud recommends that you enable this option for your SAP HANA workload, especially for multi-terabyte workloads. For more information about this option, see the SAP document SAP HANA Fast Restart Option .

This document is intended for SAP Basis and SAP system administrators who are familiar with managing SAP HANA workloads.

Before you begin

In the Google Cloud console, select the Google Cloud project where your SAP HANA workload is running.

Go to project selector
Make sure that the SID adm OS user that you use has permission to start and stop SAP HANA.

Required roles

To ensure that the service account has the necessary permissions to access secrets stored in Secret Manager, ask your administrator to grant the following IAM roles to the service account on your project:

If you are using the automation script provided by Google Cloud to enable the SAP HANA Fast Restart option, and are using Secret Manager to store the password to connect to the SAP HANA database: Secret Manager Secret Accessor ( roles/secretmanager.secretAccessor )

For more information about granting roles, see Manage access to projects, folders, and organizations .

These predefined roles contain the permissions required to access secrets stored in Secret Manager. To see the exact permissions that are required, expand the Required permissionssection:

Required permissions

The following permissions are required to access secrets stored in Secret Manager:

If you are using the automation script provided by Google Cloud to enable the SAP HANA Fast Restart option, and are using Secret Manager to store the password to connect to the SAP HANA database: secretmanager.versions.access

Your administrator might also be able to give the service account these permissions with custom roles or other predefined roles .

Enable the SAP HANA Fast Restart option

Use automation script

Google Cloud provides a script that you can use to enable SAP HANA Fast Restart option.

To enable the SAP HANA Fast Restart option by using the automation script provided by Google Cloud, complete the following steps:

Establish an SSH connection with the compute instance that's running your SAP HANA workload.
As the SID adm user, stop the SAP HANA database.

Download the sap_lib_hdbfr.sh script, which is provided by Google Cloud:

 wget  
https://storage.googleapis.com/cloudsapdeploy/terraform/latest/terraform/lib/sap_lib_hdbfr.sh

Make the sap_lib_hdbfr.sh file executable:
```
 sudo  
chmod  
+x  
sap_lib_hdbfr.sh 
```
Verify that the script has no errors:
```
 ./sap_lib_hdbfr.sh  
-help 
```
If the command returns an error, then contact Cloud Customer Care. For information about how to contact Customer Care, see Getting support for SAP on Google Cloud .

Enable the SAP HANA Fast Restart option by running the script:

 sudo  
./sap_lib_hdbfr.sh  
-h  
 ' SID 
' 
  
-s  
 SECRET_NAME

If you're not using a Secret Manager secret to provide the password, you can provide the password in plain text. However, Google Cloud recommends against this because the password gets recorded in the command-line history of the compute instance.

 sudo  
./sap_lib_hdbfr.sh  
-h  
 ' SID 
' 
  
-p  
 PASSWORD

Replace the following:

SID : the SAP system ID (SID) of your SAP HANA workload; for example AB1
SECRET_NAME : the name of the secret in Secret Manager that securely stores the password for the SYSTEM user of your SAP HANA database. The secret must exist in the same Google Cloud project that runs your SAP HANA workload.
PASSWORD : the password of the SYSTEM user of your SAP HANA database

The output is similar to the following:

 INFO  
-  
Script  
is  
running  
 in 
  
standalone  
mode
ls:  
cannot  
access  
 '/hana/tmpfs*' 
:  
No  
such  
file  
or  
directory
INFO  
-  
Setting  
up  
HANA  
Fast  
Restart  
 for 
  
system  
 'TST/00' 
.
INFO  
-  
Number  
of  
NUMA  
nodes  
is  
 2 
INFO  
-  
Number  
of  
directories  
/hana/tmpfs*  
is  
 0 
INFO  
-  
HANA  
version  
 2 
.57
INFO  
-  
No  
directories  
/hana/tmpfs*  
exist.  
Assuming  
initial  
setup.
INFO  
-  
Creating  
 2 
  
directories  
/hana/tmpfs*  
and  
mounting  
them
INFO  
-  
Adding  
/hana/tmpfs*  
entries  
to  
/etc/fstab.  
Copy  
is  
 in 
  
/etc/fstab.20220625_030839
INFO  
-  
Updating  
the  
HANA  
configuration.
INFO  
-  
Running  
command:  
 select 
  
*  
from  
dummy
DUMMY "X" 
 1 
  
row  
selected  
 ( 
overall  
 time 
  
 4124 
  
usec ; 
  
server  
 time 
  
 130 
  
usec ) 
INFO  
-  
Running  
command:  
ALTER  
SYSTEM  
ALTER  
CONFIGURATION  
 ( 
 'global.ini' 
,  
 'SYSTEM' 
 ) 
  
SET  
 ( 
 'persistence' 
,  
 'basepath_persistent_memory_volumes' 
 ) 
  
 = 
  
 '/hana/tmpfs0/TST;/hana/tmpfs1/TST;' 
 0 
  
rows  
affected  
 ( 
overall  
 time 
  
 3570 
  
usec ; 
  
server  
 time 
  
 2239 
  
usec ) 
INFO  
-  
Running  
command:  
ALTER  
SYSTEM  
ALTER  
CONFIGURATION  
 ( 
 'global.ini' 
,  
 'SYSTEM' 
 ) 
  
SET  
 ( 
 'persistent_memory' 
,  
 'table_unload_action' 
 ) 
  
 = 
  
 'retain' 
 ; 
 0 
  
rows  
affected  
 ( 
overall  
 time 
  
 4308 
  
usec ; 
  
server  
 time 
  
 2441 
  
usec ) 
INFO  
-  
Running  
command:  
ALTER  
SYSTEM  
ALTER  
CONFIGURATION  
 ( 
 'indexserver.ini' 
,  
 'SYSTEM' 
 ) 
  
SET  
 ( 
 'persistent_memory' 
,  
 'table_default' 
 ) 
  
 = 
  
 'ON' 
 ; 
 0 
  
rows  
affected  
 ( 
overall  
 time 
  
 3422 
  
usec ; 
  
server  
 time 
  
 2152 
  
usec )

As the SID adm user, start the SAP HANA database.

Manual steps

To manually enable the SAP HANA Fast Restart option for your workload, complete the following steps:

Establish an SSH connection with the compute instance that's running your SAP HANA workload.
As the SID adm user, stop the SAP HANA database.

Create directories for the NUMA nodes and mount them in the tmpfs file system:

Review the NUMA topology of your compute instance:

 sudo  
lscpu  
 | 
  
grep  
NUMA

The following is an example output for a compute instance based on the m2-ultramem-208 machine type, which has four NUMA nodes numbered 0-3. Your output is similar to this example.

 NUMA  
node ( 
s ) 
:  
 4 
NUMA  
node0  
CPU ( 
s ) 
:  
 0 
-25,104-129
NUMA  
node1  
CPU ( 
s ) 
:  
 26 
-51,130-155
NUMA  
node2  
CPU ( 
s ) 
:  
 52 
-77,156-181
NUMA  
node3  
CPU ( 
s ) 
:  
 78 
-103,182-207

Create a directory for each NUMA node and assign the ownership of these directories to the SAP HANA administrator user and group:
```
mkdir  
-pv  
/hana/tmpfs NEW_NUMA_NODE_INDEX_RANGE 
/ SID 
chown  
-R  
 SID_LC 
adm:sapsys  
/hana/tmpfs*/ SID 
chmod  
 777 
  
-R  
/hana/tmpfs*/ SID 
```
Replace the following:
- SID : the SAP system ID (SID) of your SAP HANA workload; for example AB1
- NUMA_NODE_INDEX_RANGE : the index range for the NUMA nodes available on your compute instance. For example, if your compute instance was based on the m2-ultramem-208 machine type, which has four NUMA nodes, then you'd specify the value 0..3 .
- SID_LC : the SID in lowercase; for example ab1

Mount the NUMA node directories to the tmpfs file system:

 sudo  
mount  
tmpfs SID 
0  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:0  
/hana/tmpfs0/ SID 
sudo  
mount  
tmpfs SID 
1  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:1  
/hana/tmpfs1/ SID 
sudo  
mount  
tmpfs SID 
2  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:2  
/hana/tmpfs2/ SID 
sudo  
mount  
tmpfs SID 
3  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:3  
/hana/tmpfs3/ SID

To ensure that these mount points persist after an OS reboot, add the following entries to the /etc/fstab file:

 tmpfs SID 
0 /hana/tmpfs0/ SID 
tmpfs rw,nofail,relatime,mpol=prefer:0
tmpfs SID 
1 /hana/tmpfs1/ SID 
tmpfs rw,nofail,relatime,mpol=prefer:1
tmpfs SID 
1 /hana/tmpfs2/ SID 
tmpfs rw,nofail,relatime,mpol=prefer:2
tmpfs SID 
1 /hana/tmpfs3/ SID 
tmpfs rw,nofail,relatime,mpol=prefer:3

(Optional) Because the tmpfs file system can grow and shrink dynamically, you can limit its memory usage by using the following options:
- Limit the size of a NUMA node volume:
```
 sudo  
mount  
tmpfs SID 
0  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:0,size = 
 SIZE 
  
/hana/tmpfs0/ SID 
 
```
  Replace SIZE with the size to which you want to limit the NUMA node volume. For example, 250G .
- Limit the overall memory usage of tmpfs for all NUMA for a given SAP HANA instance and given compute instance by setting the persistent_memory_global_allocation_limit in the [memorymanager] section the SAP HANA global.ini file.
From the compute instance that's running your workload, inform the SAP HANA system about the tmpfs locations by updating the [persistence] section of the global.ini file to include paths to the tmpfs location that you created in the preceding steps. Separate each tmpfs location with a semicolon.

The following example is specific to an m2-ultramem-208 instance, and specifies four memory volumes that correspond to the four NUMA nodes available on the M2 instance. If you were running SAP HANA on an m2-ultramem-416 instance, then you'd need to configure eight memory volumes.
```
 [persistence]
basepath_datavolumes = /hana/data
basepath_logvolumes = /hana/log
basepath_persistent_memory_volumes = /hana/tmpfs0/ SID 
;/hana/tmpfs1/ SID 
;/hana/tmpfs2/ SID 
;/hana/tmpfs3/ SID 
 
```
To turn on persistent memory for any SAP HANA tables or partitions, complete the following steps on the compute instance that's running your workload:
1. Turn on persistent memory for the SAP HANA table or partition, run the following SQL query:
```
  ALTER 
  
 TABLE 
  
  TABLE_OR_PARTITION_NAME 
 
  
 persistent 
  
 memory 
  
 ON 
  
 immediate 
  
 CASCADE 
 
```
  Replace TABLE_OR_PARTITION_NAME with the name of the table or partition.
2. Update the memory persistence settings by adding the table_default parameter in the indexserver.ini file:
```
 [persistent_memory]
table_default = ON 
```
For information from SAP about how to control columns, tables, and which monitoring views provide detailed information, see Persistent Memory .
As the SID adm user, start the SAP HANA database.

Modify the fast restart configuration after increasing compute instance size

After you increase the size of the compute instance that hosts your SAP HANA workload, you must update the SAP HANA Fast Restart configuration to match the new NUMA topology.

To modify the configuration of the SAP HANA Fast Restart option for such a scenario, complete the following steps:

Establish an SSH connection with the resized compute instance that runs your workload.
As the SID adm user, stop the SAP HANA database.
Make note of the NUMA topology of the resized compute instance:
```
 sudo  
lscpu  
 | 
  
grep  
NUMA 
```

Clear the occupied memory by unmounting the existing tmpfs file systems:

 sudo  
umount  
/hana/tmpfs0/ SID 
sudo  
umount  
/hana/tmpfs1/ SID 
sudo  
umount  
/hana/tmpfs2/ SID 
sudo  
umount  
/hana/tmpfs3/ SID

Replace SID with the SID of your SAP HANA database, for example ABC .

For each new NUMA node, create a directory and assign the ownership of these new directories to the SAP HANA administrator user and group:
```
mkdir  
-pv  
/hana/tmpfs NEW_NUMA_NODE_INDEX_RANGE 
/ SID 
chown  
-R  
 SID_LC 
adm:sapsys  
/hana/tmpfs*/ SID 
chmod  
 777 
  
-R  
/hana/tmpfs*/ SID 
```
Replace the following:
- NEW_NUMA_NODE_INDEX_RANGE : the index range that denotes the new NUMA nodes. For example, imagine that your compute instance was based on the m2-ultramem-208 machine type, which has four NUMA nodes ( 0..3 ). If you resized your instance to use the m2-ultramem-416 machine type, which has 8 NUMA nodes, then you'd specify the range 4..7 .
- SID_LC : the SID in lowercase; for example abc

Mount each new NUMA node directory to the tmpfs file system:

 sudo  
mount  
tmpfs SID 
 SERIAL_NUMBER_OF_NEW_NODE 
  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer: SERIAL_NUMBER_OF_NEW_NODE 
  
/hana/tmpfs SERIAL_NUMBER_OF_NEW_NODE 
/ SID

For example, if you resized from m2-ultramem-208 (4 NUMA nodes) to m2-ultramem-416 (8 NUMA nodes) for a system with SID ABC , then you'd have to run the following:

 sudo  
mount  
tmpfsABC4  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:4  
/hana/tmpfs4/ABC
sudo  
mount  
tmpfsABC5  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:5  
/hana/tmpfs5/ABC
sudo  
mount  
tmpfsABC6  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:6  
/hana/tmpfs6/ABC
sudo  
mount  
tmpfsABC7  
-t  
tmpfs  
-o  
 mpol 
 = 
prefer:7  
/hana/tmpfs7/ABC

To ensure that these mount points persist and are available after an OS reboot, add an entry for each new mount point to the /etc/fstab file:

 tmpfs SID 
 SERIAL_NUMBER_OF_NEW_NODE 
/hana/tmpfs SERIAL_NUMBER_OF_NEW_NODE 
/ SID 
tmpfs rw,relatime,mpol=prefer: SERIAL_NUMBER_OF_NEW_NODE

Continuing with the example:

 tmpfsABC4 /hana/tmpfs4/ABC tmpfs rw,relatime,mpol=prefer:4
tmpfsABC5 /hana/tmpfs5/ABC tmpfs rw,relatime,mpol=prefer:5
tmpfsABC6 /hana/tmpfs6/ABC tmpfs rw,relatime,mpol=prefer:6
tmpfsABC7 /hana/tmpfs7/ABC tmpfs rw,relatime,mpol=prefer:7

Inform the SAP HANA system about the new tmpfs locations, update the [persistence] section of the global.ini file to include paths to the new tmpfs locations that you created. Separate each tmpfs location with a semicolon.

Continuing with the example, the updated global.ini file looks similar to the following:
```
 [persistence]
basepath_persistent_memory_volumes = /hana/tmpfs0/ABC;/hana/tmpfs1/ABC;/hana/tmpfs2/ABC;/hana/tmpfs3/ABC;/hana/tmpfs4/ABC;/hana/tmpfs5/ABC;/hana/tmpfs6/ABC;/hana/tmpfs7/ABC; 
```
As the SID adm user, start the SAP HANA database.

Modify the fast restart configuration after decreasing compute instance size

After you decrease the size of the compute instance that hosts your SAP HANA workload, you must update the SAP HANA Fast Restart configuration to match the new NUMA topology.