BlackBerry Connection > IT Edition > Admin Tip: Optimizing High Availability

Admin Tip: Optimizing High Availability

The peace of mind from High Availability (HA) is a built-in feature of BlackBerry® Enterprise Server. This month's admin tip illustrates how proactive administrators can optimize HA's power, flexibility, and configurability to keep their BlackBerry environment up and running.

When you're dealing with unplanned downtime, every minute counts. Certainly that's when administrators appreciate the built-in high availability of BlackBerry Enterprise Server v5.0 that is designed to enable faster recovery from unplanned outages. Once configured, features such as automatic failovers and database mirroring can help provide peace of mind and flexibility for administrators looking to increase redundancy and fault tolerance in ways that best meet their organizational needs.

Automatic failovers

BlackBerry Enterprise Server v5.0 allows for a smooth transition from a primary server to a failover server with little or no further interaction after primary configuration.

When initially configuring a highly available BlackBerry environment, you install a primary BlackBerry Enterprise Server and a standby BlackBerry Enterprise Server on different computers within the same network segment. These BlackBerry Enterprise Server instances create a BlackBerry Enterprise Server pair. The standby BlackBerry Enterprise Server connects to the primary BlackBerry Enterprise Server and checks periodically that the primary BlackBerry Enterprise Server is healthy. BlackBerry Enterprise Server health is determined by thresholds that you can configure. If the health of the primary BlackBerry Enterprise Server falls below the failover threshold or if the primary BlackBerry Enterprise Server stops responding, the standby BlackBerry Enterprise Server can promote itself to primary and then continues to deliver functionality to BlackBerry smartphones.

BlackBerry Enterprise Server v5.0 gives control of automatic failover thresholds to the BlackBerry administrator, meaning that many of the failover settings are at the discretion of the administrator.

Several configurable thresholds

Two important, non-configurable failover parameters are already in place with BlackBerry Enterprise Server. They are:

  1. Wireless Network Access: This allows the BlackBerry Router to contact the BlackBerry Network. This is the highest failover parameter.
  2. BlackBerry Dispatcher is the second highest failover parameter. The BlackBerry Dispatcher Service can encrypt and compress all outgoing data packets.

There are another 14 configurable parameters that an administrator can set in order to personalize the failover to each organization’s specific needs.

These different thresholds appear in the form of a list with up and down arrows. The order of the list and the placement of the threshold within the list define the importance of the threshold and where it fits on the list of the health score. The higher the threshold is on the list, the more important it is in terms of heath score reporting.

Database Mirroring

BlackBerry Enterprise Server v5.0 also supports database mirroring. This takes a customer’s highly available environment one step further and allows complete system redundancy in case of a catastrophic server failure.

Database Mirroring is only supported with Microsoft® SQL Server® 2005 Service Pack 2, and supports Principal/Partner failover as well as Principal/Witness/Partner failover for complete automation. The BlackBerry Enterprise Server receives status updates from the SQL Server, helping to ensure that connectivity is maintained. With database engines older than SQL 2005 SP2, One-Way Transactional Replication can be configured but failovers will have to occur manually as opposed to automatically.

In the event that the SQL server that is hosting the BlackBerry Configuration Database experiences a failure, the BlackBerry Enterprise Server is updated and seeks out the partner of the principal database and can immediately make a connection.

Here's an example from a test environment. Note that the principal database is residing on SQL Server SCARECROW, and the failover database is on SQL Server MEDDLE.

{0x8F0} (001,1) Received REPORT_HEALTH_SCORE command,
Health=0x0000000002001501, Mask=0x000000000200150F, Users=1,
Servers=1 SCARECROW

Above we receive a health check from the Principal SQL Server, updating the BlackBerry Enterprise Server regarding its availability.

{0x8F0} COM Error 0x80004005 in ConnectionItem::ValidateConnection - TCP Provider: An existing connection was forcibly closed by the remote host.

Here, we experience a connectivity drop from the SQL Server.

{0x8F0} Dispatcher Database connection dropped {0x8F0} Health score: Health=0x0000001753101509

In the two log lines above, we lose our BlackBerry Dispatcher connection, and receive a failure heath check.

{0x8F0} [ENV] [DB] Connection String =
Server=scarecrow;Database=BESMgmt;Trusted_Connection=Yes
[30000] (05/13 18:37:41.925):{0x8F0} [ENV] [DB] DBMS Name =
Microsoft SQL Server; DBMS Version = 09.00.3042; Provider Name =
sqlncli.dll; Provider Friendly Name = Microsoft SQL Native Client; OLE
DB Version = 02.80; Provider Version = 9.00.3042.00; Failover Partner =
MEDDLE

Here, we detect that SCARECROW's partner, MEDDLE, is online and ready for database failover.

{0x8F0} [ENV] [DB] Database Schema Version: 5.0.0 ‹5.0.2009.03.19›
{0x8F0} [ENV] [DB] File Group: PRIMARY, Log.File: BESMgmt_data, #1,
[C:\Program Files\Microsoft SQL
Server\MSSQL.1\MSSQL\DATA\BESMgmt.mdf], Size: 102400 Kb, Limit:
Unrestricted growth, Growth: 25600 KB
{0x8F0} [ENV] [SRV: MEDDLE] Comp. Name: MEDDLE, Edition:
Enterprise Edition, Product Version: 9.00.3042.00, Service Pack: (SP2) S
rv Collation: SQL_Latin1_General_CP1_CI_AS
{0x8F0} [ENV] [DB: BESMgmt] , Status: ONLINE, Recovery Model: FULL, Db Collation: SQL_Latin1_General_CP1_CI_AS
{0x8F0} Dispatcher Database connection established

In the above lines, we see that the database is online, set for FULL recovery, and we establish a connection to it.

After the failover, mail flow resumes as normal from the primary BlackBerry Enterprise Server. In our example, the SQL Server experienced the failover, not the BlackBerry Enterprise Server. The BlackBerry Enterprise Server has the ability to continue working with a momentary disconnect from the SQL server, resulting in no noticeable impact on mail flow.

Connected, available, and operational

Remember, one of the greatest benefits of BlackBerry Enterprise Server v5.0 is that no special hardware (such as special network cards) or software is required to achieve high availability. It is built right into the server software at the application (software) level, helping to maximize the productivity benefits of your mobility, while reducing calls to your IT help desk in the event of a server failure.

BlackBerry Enterprise Server high availability »

BlackBerry Enterprise Server Express

Support Forums

The BlackBerry® Support Community Forums are a great place for your BlackBerry device users to get help—and a place for you to connect with other IT administrators. Do you have questions about BlackBerry Enterprise Solutions? Are you looking for support on devices or accessories? Visit the BlackBerry Support Community Forums.