Versant High Availability Backup (HABackUp) is an add-on software module that enables Versant Object Database to use the disk mirroring features of EMC Symmetrix or other enterprise storage systems to take an online backup of very large data volumes without impacting availability.
Increasingly, big enterprises are deploying Versant Object Database in mission critical applications. Typically, such customers use mirrored disk devices for high performance and availability. High Availability BackUp provides
Versant High Availability Backup solution is a generic way of achieving continuous online backup of Versant Object Database. It exploits the capabilities of special storage devices. It allows the user to execute certain operations such as, splitting a mirrored device, after bringing the database to a consistent state. Thus, a copy of the database can be made at a consistent point without jeopardizing server availability, data integrity and performance. Subsequently, this copy can be used for various purposes including, continuous online backup and stand-by database for DSS applications.
Versant Incremental backup (VBackUp) strategy consists of three different backup levels viz. level 0, 1 and 2. As database size increases, it becomes more important to set the level in a way, which minimizes backup size and time. Level 0 performs a full backup. Level 1 backs up all changes made since the last level 0 backup. Level 2 backs all changes made since the last level 0 or level 1 backup, whichever was most recent. Roll-forward (RF) archiving is another feature that preserves logical log records generated by a database during normal operation in a log archive. These records can be replayed on the database during recovery. Thus, RF makes it possible to recover a database to its state just prior to the crash.
The habackup solution is an extension that exploits the device mirroring functionality of the modern disk arrays.
A device pair consists of a mirror device and a standard device. The standard device (on which production database resides) can have any mirror structure (unprotected, RAID, RAID with SRDF). After configuration and initialization of a mirrored disk array, the mirror devices contain no data. The device pair should be synchronized so that both the standard and mirror devices contain the same data. Typically the device vendors provide the ability to synchronize and split mirrored pair.
Figure 1 illustrates a Versant object database [say, production_db] in operation. The system, physical log and logical log volumes are shown to be residing on mirrored disk array.
A split operation is carried out by using the –split command of habackup, which ensures that the appropriate timestamp fields on the database are updated and at the same time it is in a consistent state before the split operation is issued. The (device) vendor-specific command to be executed for a split operation is indicated by the -cmd option to habackup. Habackup executes this command or even a script and waits for it to finish. It is assumed that the vendor specific split command or script would return an error if it is unsuccessful. Based on the error returned, habackup will either complete or abort the split. The database image on the mirror device, obtained after the split operation, is a consistent snapshot of the database, which can be archived to a backup media. The "-split" command of habackup is synonymous to level 0 backup of vbackup.
Habackup also offers the ability to perform incremental backups. After performing split it is possible to take level 1 or level 2 backups of the production database.
Roll-forward archiving can be enabled with -roll option during split or level 1/2 backups. Similar to vbackup utility, -log option can be used to start the archive process and -off to stop it.
In the event of a crash, the standard device can be restored by forming device pairs (operation against of split) using the commands provided by device vendors. After the device level restore takes place, the standard device contains the snapshot of the database at the time of split. The level 1/2 backups and RF archives of the production database after the split, are useful at this point to bring the database to the state just prior to crash.
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Add-on Modules for the Versant Object Database.
If mission critical deployments are a part of your business or if you need to access data through SQL, Versant provides Enterprise-class Add-on Modules for the Versant Object Database.
The observation of a production system is a cornerstone to the proper establishment of an adequate System & Network Management policy.
Using Versant Vitness for the advanced monitoring of your entire Versant Object Database environment provides you with a fundamental tool for all database administration operations and decisions.
The Vitness add-on module delivers real-time views of performance data and analytical information about the Versant Object Database at the push of a button. Proactive database monitoring prevents potential faults that could be unexpectedly generated by an unobserved system - Versant Vitness alerts administrators before database availability is affected. Can life get any easier?
Versant Vorkout is a Database Reorganizer Tool for applications that delete large numbers of objects. It lets you reclaim unused space in your database while it is in normal operation, increasing available free space and improving database performance. Last but not least Vorkout is tightly integrated and can be used through Versant Vitness.
Over time as objects grow or are deleted, empty holes are created in the tightly packed database resulting in fragmentation of data segments. Thus, performance starts degrading and disk usage is also increased.
Versant has addressed this issue by introducing Vorkout - the enhanced tool provides the user the ability to analyze a database for wasted space and reorganizes the data for reduced fragmentation and restored performance.
Vedding is an add-on software module for the Versant Object Database enabling automatic fail-over and recovery in the case of hardware or software failure. This is commonly known as a Fault Tolerance environment.
Vedding uses synchronous replication between two database instances and supports transparent re-synchronization in the event of a failure. Synchronous database replication mirrors the contents of one database to another in a predictable and orderly manner. This provides either local or geographically remote redundancy, which protects against the unavailability of data.
The Vhistle add-on module for Asynchronous Replication supports both master-slave and peer-to-peer asynchronous replication between multiple Versant Object Database servers. This can be used to replicate data to a distributed recovery site or to replicate data between multiple local object servers for increased performance and reliability.
In many applications, there is a need to replicate data, typically to improve availability, to improve performance by geographically co-locating databases with the applications that access the databases, to isolate decision support systems from online production systems, and to help in recovery from failures using warm-standby systems.
Vhisper provides Warm Standby capabilities to a Versant Object Database. The add-on module is used as an incremental rollforward recovery. It is designed to minimize the downtime in an emergency event.
With Vhisper, an up-to-date copy of the primary database is maintained - this is a Warm Standby database. In case of an emergency, the Vhisper's Warm Standby database can be updated very quickly to the state of the primary database. Instead of starting a full database restore that may take a considerable time with large databases, you just need to apply the last roll forward archive plus the logical.log of the primary database to the Warm Standby database - and you are ready for anything.
Varehouse is an add-on software module that enables the Versant Object Database to use the disk mirroring features of EMC Symmetrix or other enterprise storage systems to take an online backup of very large data volumes without impacting availability (High Availability Backup, HAbackup).
Varehouse, Versant's High Availability Backup solution, is a generic way of achieving continuous online backup of the Versant Object Database. It exploits the capabilities of special storage devices. It allows the user to execute certain operations such as, splitting a mirrored device, after bringing the database to a consistent state.
Vildcard enables you to run a discounted standby server in parallel to your initial Versant Object Database server.
Most likely, Vildcard is used for generic cold standby environments where backups are accomplished manually in certain periods.
reVind is an Add-on module for the Versant Object Database. The Versant/SQL suite of software modules permits you to use conventional Structured Query Language (SQL) semantics to access data that resides in a Versant Object Database.
The resulting application architecture can offer the strengths of both the relational and the object database models, such as the openness and interconnectivity of relational tables along with the expressiveness and performance of object collections.