Save point in SAP HANA

 

1.What are savepoints?

• Savepoints are required to synchronize changes in memory with the persistency on disk level. All modified pages of row and column store are written to disk during a savepoint.


• Each SAP HANA host and service has its own savepoints.


• The data belonging to a savepoint represents a consistent state of the data on disk and remains untouched until the next savepoint operation has been completed.

 

2.When is a savepoint triggered?

• 
  

  Savepoint interval(automatic)

  
  During normal operations, savepoints are automatically triggered when a predefined time since the last savepoint is passed. The length of the time interval between two consecutive savepoints can be controlled with the following parameter:
  
  global.ini -> [persistence] -> savepoint_interval_s
  
  Its default value is 300, so savepoints are taken at intervals of 300 seconds (5 minutes).


• 
  

  System command (manual)

  
  The following command can be used to execute a savepoint manually:
  
  ALTER SYSTEM SAVEPOINT


• 
  

  Soft shutdown

  
  A soft shutdown invokes a savepoint before the services are stopped.
  
  A hard shutdown doesn't trigger a savepoint. This can increase the subsequent restart time.


• 
  

  Backup

  
  A global savepoint is performed before a data backup is started.
  
  A savepoint is written after the backup of a specific service if finished.


• 
  

  Startup

  
  After a consistent database state is reached during startup, a savepoint is performed.


• 
  

  Snapshots

  
  Snapshots are savepoints that are preserved for longer use and so they are not overwritten by the next savepoint.

attach mount point to EBS volume using script

 #!/bin/bash

#attach the EBS drive from the console to /dev/sdf

#list the volumes

lslbk

#check if the volume has any data

sudo file -s /dev/xvdf

#format the volume as ext4

sudo mkfs -t ext4 /dev/xvdf

#create a directory

sudo mkdir /myexternalvolume

#mount our EBS to our directory

sudo mount /dev/xvdf  /myexternalvolume

output for the above script:

# with the above process the mount point will save temporarily, To save new mount point changes permanently. edit fstab file.

sudo nano /etc/fstab

 manually activity:

/dev/xvdf    /myexternalvolume  ext4 defaults,nofail    0   0 

press ESC 
:wq!

cat /etc/fstab --> check our new entry.

Linux command to add mount point to device

To add new mount point to device /dev/xvdf

$sudo mount /dev/xvdf /mnt/new_folder

To unmount a exist mount point

$sudo unmount /mnt/new_folder