Host, Database,system,default layers, Parameters configuration in SAP HANA

 Host layer: it has the highest priority when a parameter is configured in the host layer have more      importance then Database,system,default layers.
Database layer: parameters defined here are specific to tenant database, when a parameter is configured  in the Database layer have more importance then system,default layers.
System layer:parameters defined here are for all tenant databases in one system DB, when a parameter is configured  in the system layer have more importance then default layers.

Default layer: it have least priority among all the 4 parameter layers.

EC2 Dedicated host

 * You reserve an entire host on AWS cloud and you launch EC2 instances directly on it.

* it can help in a BYOL(bring your Own license) model or when you have strong regulatory, compliance or security requirements.

* it's overall more expensive and should not use it unless strongly required. you can also reserve dedicated hosts.

Hands for launching dedicated host:

Navigate to instances --> Dedicated Hosts

Click on Allocate a host, as shown below.                                                                                               

provide details:

1. choose instance type for dedicated host.
2. Available zone for the dedicated host.
3. allow instance auto-placement - basically an auto scale of dedicated EC2 instance option.
4. quality of dedicated EC2 instance.
5. finally click on Allocate host as highlighted below.

host connectivity check using Linux scripts using exit code

cat connect_check.sh

#!/bin/bash

HOST="google.com"

ping -c 4 $HOST

if [ "$?" -eq "1" ]                        #exit code test condition

then

echo " $HOST is reachable "

else

echo " $HOST unreachable "

fi

Output

./connect_check.sh

PING google.com (172.217.17.78) 56(84) bytes of data.

From 10.188.34.2 icmp_seq=1 Destination Host Unreachable

From 10.188.34.2 icmp_seq=2 Destination Host Unreachable

From 10.188.34.2 icmp_seq=3 Destination Host Unreachable

From 10.188.34.2 icmp_seq=4 Destination Host Unreachable

--- google.com ping statistics ---

4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 2998ms

 google.com is reachable

To check the list of users logged in to the host using putty

$ w