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vCenter Server Database retention purge schedule

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The size of your vCenter Server Database is largely based on the amount events/tasks and performance statistics that you retain for your vSphere environment. You can view and edit these settings by going to the vCenter Server "General" settings as shown in the screenshot below (documentation here and here):

vcenter-server-data-retention
A common misconception when changing any one of these retention policies, especially when decreasing the amount of data to be retained, is that the existing data would be purged immediately to comply with the new settings. This is actually not the case and for data that is applicable for removal, there are a set of purge jobs that run on a specific schedule to perform the clean up. Below is the schedule in which these database jobs run for each of the data types:

Performance Statistics:

  • Daily Level - Once every 30 minutes starting at 00:00 (e.g. 00:00, 00:30, 01:00, etc.)
  • Weekly Level - Once every 2 hours starting at 01:45 (e.g. 01:45, 03:45, 05:45, etc. )
  • Monthly & Yearly Level - Once a day at 02:15

Events and Tasks:

  • Once a day at 00:15

For customers that are looking for immediate results and reclaim storage from within their VCDB, you can take a look at the following VMware KB 1025914 which outlines the specific instructions. This can especially be useful if you are looking to perform a Windows vCenter Server to vCenter Server Appliance Migration and wish to reduce the overall amount of data that is being copied over from your existing environment.

How to check the size of your Config & SEAT data in the VCDB in vPostgres?

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After publishing my article on how to check the size of your vCenter Server's Configuration and Stats, Events, Alarm & Tasks (SEAT) data for both a Microsoft SQL Server and Oracle based database, I had received a few requests for doing the same for the vPostgres database which the vCenter Server Appliance (VCSA) uses exclusively. Thanks to one of our Engineers who works on the VCDB, I was able to quickly get the relevant SQL query to perform the exact same lookup as the other two databases.

Since the VCSA is harden and locked down by default, being able to remotely retrieve this information will actually require some additional configuration changes to your VCSA which may or may not be acceptable. Because of this constraint, I will provide two options in how you can perform this SQL query.

The first option (easy) will be running the SQL query directly from within the VCSA. You just need SSH access and no other information or credentials will be required. The second option (complex) will be to remotely connect to the vPostgres database (generally not recommend) which will require the VCDB's credentials which I will show you how to retrieve. Lastly, I want to quickly mention that in the upcoming vSphere 6.5 release, this information will be super easy to view not only from a UI but also API as shown in tweet below.

 

Option 1:

Step 1 - Download the following shell script called queryVCDBvPostgres.sh which contains the respective VCDB SQL query.

Step 2 - SCP the shell script to your VCSA and then login via SSH.

Step 3 - Run the following command to make the script executable:

chmod +x queryVCDBvPostgres.sh

Step 4 - Run the script by issuing the following command:

./queryVCDBvPostgres.sh

Here is a screenshot of what you should see which is a break down of your Config + SEAT data:

query-vcdb-config-seat-data-vpostgres-0

Option 2:

Step 1 - Login to the VCSA using SSH.

Step 2 - Edit /storage/db/vpostgres/postgresql.conf and add the following entry:

listen_addresses = '*'

This will allow vPostgres to be connected to from any address or if you want to restrict it to a specific IP, you can also just specify that.

Step 3 - Edit /storage/db/vpostgres/pg_hba.conf and add the following entry:

host    all             all             172.30.0.0/24            md5

Similiar to the previous configuration, you can either specify a network range using CIDR notation or a specific IP Address.

Step 4 - Edit /etc/vmware/appliance/firewall/vmware-vpostgres and replace it with the following entry:

{
  "firewall": {
     "enable": true,
        "rules": [
        {
          "direction": "inbound",
          "name": "vpostgres_external",
          "port": "5432",
          "portoffset": 0,
          "porttype": "dst",
          "protocol": "tcp"
        }
     ]
  },
  "internal-ports": {
    "rules": [
      {
        "name": "server_port",
        "port": 5432
      }
    ]
  }
}

This will open up the VCSA's firewall to allow remote connections to the vPostgres port which the default is 5432.

Step 5 - Next, we need to reload the firewall configuration by running the following command:

/usr/lib/applmgmt/networking/bin/firewall-reload

Step 6 - We can verify by running the following command:

iptables -L | grep postgres

Here is a screenshot of what you should see as the output:

query-vcdb-config-seat-data-vpostgres-2
Step 7 - Lastly, we need to restart the vPostgres service by running the following command:

service vmware-vpostgres restart

Step 8 - To verify that you can now remotely connect to the vPostgres DB, run the following command:

netstat -anp | grep LISTEN | grep tcp | grep 5432

Here is a screenshot of what you should see as the output:

query-vcdb-config-seat-data-vpostgres-3
At this point, you have now enabled remote connections to the VCSA's vPostgres DB. The next step is to retrieve the VCDB credentials which you will do so using a PowerShell script that I have written to perform the remote SQL query. This will also require that you setup an ODBC connection on your client system to communicate with the vPostgres DB. Please have a look here for more information on how to setup the ODBC connection.

Step 9 - Login to VCSA via SSH and then look at the /etc/vmware-vpx/vcdb.properties and you should see the password to your VCDB. Go ahead and record this some where as you will need it in the next step. The username for the DB will be vc which you can also make a note of.

Step 10 - Download the following PowerShell script called Get-VCDBUsagevPostgres.ps1 and provide the connection details that you retrieved in Step 9. If everything was properly configured, you can run the PowerShell script and it should produce a similiar output as shown in the screenshot below.

query-vcdb-config-seat-data-vpostgres-1

How to check the size of your Config + Stats, Events, Alarms & Tasks (SEAT) data in the VCDB?

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I think many of you know that I am not a fan of anyone poking around in the vCenter Server Database (VCDB) and having to manually craft SQL queries to retrieve information about their vSphere environment. This is especially true when you can easily and painlessly retrieve all of this information by simply using the vSphere API.

Having said that, there is one use case that is currently not available today in the API, yet. The use case that I am referring to is having better visibility into the storage utilization of our VCDB for things like the Core inventory configuration as well as the Stats, Events, Alarms and Tasks (SEAT) data which generally makes up the bulk of the VCDB data. Some of the benefits to having this information includes understanding the size of your VCDB given your current inventory size + data retention policy, whether or not you should consider reducing/truncating your dataset and even ensuring that vCenter Server rollup jobs have properly ran by simply getting visibility into the current storage footprint of your VCDB.

The other really nice benefit of having this information for those looking to use the recently released VCSA Migration Tool (migrating from Windows vCenter Server to the vCenter Server Appliance) is that it can be used to help calculate the estimated amount of downtime that is required for the migration to complete. The process is currently outlined in the following VMware KB 2146420 which requires customers to manually run a specific SQL query to retrieve the specific tables within the VCDB, perform some basic arithmetic with the results and then plugging them into an excel spreadsheet to provide the time estimations for migration.

UPDATE (10/20/16) - For customers already on the VCSA, you can also perform this query for vPostgres DB by taking a look at this blog post here.

Note: The migration time estimates from VMware are just that, estimates. There are many other factors such as source and destination hardware capabilities, network and storage bandwidth that may influence the amount of time a migration may take. It is recommended that customers use the estimates as guidance and still add a time buffer to their maintenance window.

To help simplify the consumption of the KB, I have created a small PowerShell script called Get-VCDBUsage.ps1 which will allow you to remotely connect to your VCDB (assuming you have enabled remote connectivity) to execute the correct SQL query based on your database platform and provide you with the results. The script also includes an optional parameter which will automatically take the results and calculate the estimated amount of downtime required for migrating from your Windows based vCenter Server to the VCSA. This makes gathering the information about your VCDB quite easy without having to manually go through the KB which can be challenging if you have a large amount of vCenter Servers.

The script supports the following 3 modes:

  • Running "locally" on the Microsoft SQL Server DB (requires Windows PowerShell Extensions for SQL Server as I rely on the Invoke-Sqlcmd cmdlet)
  • Running "remotely" connected to the Microsoft SQL Server DB
  • Running "remotely" connected to the Oracle DB (requires Oracle ODAC Client to be installed on the Windows system running the script)

For the first mode, you only need to specify the dbType, connectionType and dbInstance parameters as it will use the existing local ODBC connection so you do not have to provide any DB credentials. Here is an example command:

Get-VCDBUsage -dbType mssql -connectionType local -dbInstance VCDB

For the second mode, you will need to specify the dbType, connectionType, dbServer, dbPort, dbInstance, dbUsername and dbPassword parameters as you will be connecting remotely and the additional DB information will be needed. Here is an example command:

Get-VCDBUsage -dbType mssql -connectionType local -dbServer sql.primp-industries.com -dbPort 1433 -dbInstance VCDB -dbUsername sa -dbPassword VMware1!

Here is a screenshot of what the output would look like whether you run this against a VCDB running on either Microsoft SQL Server or Oracle system. As you can see, you get a nice break down of the 4 more interesting tables: Core configuration, Alarm, Events and Stats data.

how-to-check-size-of-vcenter-server-database-0
If you wish to also calculate the estimated VCSA migration time, you simply just need to append the -migration_type parameter which accepts a value of option1 or option2. When performing the Windows vCenter Server to VCSA Migration, customers have the option of either only migrating the Configuration + Alarm data which I am referring to as Option 1 (default) or you can migrate all data which includes Configuration + Alarm + Event + Stats which I am referring to as Option 2. By simply changing the parameter in the script, you can get an idea of the time estimate as well as the amount of data (in GB) that would be migrated. Here is an example command:

Get-VCDBUsage -dbType mssql -connectionType local -dbServer sql.primp-industries.com -dbPort 1433 -dbInstance VCDB -dbUsername sa -dbPassword VMware1! -migration_type option1

Here is a screenshot of what the output would look like with the additional parameter.

how-to-check-size-of-vcenter-server-database-1
As you can see, you can easily run this script non-disruptively against your VCDB and assess the amount of data that could potentially be migrated as well as the amount of downtime required for a given migration scenario. This is also a great time to consider whether or not you need all of this data, especially when it comes to the Performance Stats. For Tasks/Events, this data is generally useful for auditing purposes and some of our customers must retain a certain amount for compliance purposes. However, for the Performance Stats, this information may not be as useful as some of you may think. As vCenter Server performs its daily, weekly and monthly rollup jobs, the statistics are continuously averaged out to the point where the granularity of the original data points are pretty lost. This means that you end up storing a ton of data that is really not all that useful. For fine grain historical stats, solutions like vRealize Operations Manager should be considered and vCenter Server should really be used for short term historical stats and quick ease of access for troubleshooting purposes. For more details on calculating the estimated amount of downtime for migration, please refer to VMware KB 2146420.

One last note, as you may have noticed from the screenshot or running the script that at the end of the output there is a question asking if you would like to compare your VCDB stats with others. If you do decide to share  the information(completely optional) which only includes the size for the each of the tables and number of rows that will be sent off to a public github repository https://github.com/migrate2vcsa. If we get enough submissions, we may do some fun things with the data and report back to the community. The data is anonymous and it might be interesting to see how your data set compares to others.