You can choose from three administrative interfaces—a Java-based GUI interface, a Web-based interface that communicates with an Apache-based Web server installed with the product, and a command-line interface. Figure 5 shows the Web interface displaying the status of two clusters. All three interfaces offer full functionality, including the ability to remotely administer multiple clusters. You control access to administrative functions by using a new component, VERITAS Security Services, that lets you grant authority over clusters to VERITAS-defined users and groups (which you can associate with existing Windows users and security groups). Security Services also supports other Lightweight Directory Access Protocol (LDAP) security services, such as Network Information Service (NIS), in multi-OS environments.
Storage Foundation HA’s Volume Replicator performs block-based replication—intercepting and duplicating I/O to a logical volume—and includes features of VERITAS Volume Manager, now renamed VERITAS Storage Foundation. Storage Foundation HA supports both synchronous and asynchronous replication. A soft-synchronous mode writes in synchronous mode until the communication link to the remote volume fails. When remote writes are uncompleted for a user-configurable length of time, the replication engine begins to queue writes until communication to the remote volume is restored.
After a failover, replicating data back to the primary node so that the application can again run on that node can take a long time. Storage Foundation HA tracks which blocks of a logical volume are updated following a failover and, when the time comes to fail back, replicates only the changed blocks back to the primary node.
Storage Foundation HA includes features that help you set up replication. Given sufficient unallocated volume space on the target system, Storage Foundation HA automatically creates volumes to match the volumes on the source system. Storage Foundation HA is aware of a variety of both hardware- and OS-based data mirroring products and distinguishes between a mirror broken by administrative action or by an error event.
Storage Foundation HA virtualizes a variety of cluster node resources—including IP address and host name-assigning them to the backup node at failover. Storage Foundation HA supports workload management features, so you can specify a minimum level of free resources that a node must have before Storage Foundation HA will consider it an eligible failover node. Storage Foundation HA costs $3995 for Windows 2003 Standard Edition and Win2K Server, $4995 for Windows 2003 Enterprise Edition and Win2K AS, and $49,995 for Windows 2003 Datacenter Edition and Win2K Datacenter Server.
BrightStor High Availability
Computer Associates' (CA's) BrightStor High Availability is a replication-based application failover system designed for use with standard server hardware running Windows 2003, Win2K Server, or Win2K AS. Process-monitoring technology from CA's Unicenter, combined with a heartbeat mechanism, monitors the health of primary and standby servers at several levels. Configurable IP ping-based checking distinguishes server-based communication failures from network-related problems and verifies that the communications path to the servers are working. Application-specific monitoring checks the health of the protected application service or process. When BrightStor detects a failure, it attempts to restart a failed service or process before declaring failure and initiating a failover. When the primary server becomes active again after a failover and sees that the backup server is active, BrightStor deactivates the primary’s resources that failed over to the backup server (e.g., IP addresses, server names). This feature helps to avoid split-brain processing.
BrightStor uses protection tasks to define application replication and failover parameters. When creating a protection task for an application, you specify the application’s executable files and installed services, the source and destination for replicated data if any, IP addresses that will fail over to the stand-in server, and addresses that the out-of-service primary server will use. BrightStor also supports applications that replicate their own data. For some applications, including SQL Server and Exchange, BrightStor can automatically detect application parameters and configure itself for replication and failover. BrightStor supports another list of applications, including some non-Microsoft email and database management systems (DBMSs), with a set of user-customizable scripts that make setup easier.
BrightStor has three modes of operation. Full Protection causes the protected application to fail over to the stand-in server when failover conditions are met. In Data Protection Only mode, the protection task replicates data to the secondary server until a failure, but the application doesn't fail over. Failover Only performs failover when the conditions are met but doesn't perform data replication. BrightStor also supports failover to nodes residing on remote subnets. For more information about BrightStor's methods for failing over server IP addresses, see "Remote Cluster Considerations."
BrightStor's Alert Services component lets you configure who will receive notification of failover events and of service and process failures that the protection task monitors. Alert Services can send notifications through SNMP traps, email messages, or pages.
For a successful failover to occur, the protection task must be running on the primary server, and BrightStor High Availability Manager must be running on the secondary server. After you've corrected the problem that caused the failover, you run the BrightStor Reinstatement Wizard, which guides you through the process of replicating changed data back to the primary server before failing the application back to it. Performing a normal shutdown of the primary server won’t cause a failover—BrightStor sees a shutdown as a nonfailure event.
You use the BrightStor High Availability Manager GUI, a Win32 application that Figure 6 shows, to configure protection tasks and manage BrightStor tasks and alerts on the servers. It runs on Windows 2003, XP, and Win2K computers. The user ID that BrightStor High Availability Manager runs under must have administrative authority over the server being managed.
Replication is asynchronous. You specify the data to be replicated to the secondary server at the directory level. A file filter allows more granular control over which files in a directory structure are replicated. Drive letters and directory structures on the secondary server need not be the same as on the primary server.
BrightStor keeps track of disk sectors that change while an application runs on the backup server, so when you fail the application back to the primary server, BrightStor replicates back only the changes. BrightStor licensed for one primary server and one secondary server costs $2495.
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