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Disk-based Backup does not Magically Break the Corporate LAN Bottleneck

It’s easy for organizations to believe that disk will solve their backup problems. But some organizations are starting to discover that while disk solved some of their backup problems, they are still not realizing the full reductions in backup times and improved performance rates on their application servers that they may have initially expected. If an organization finds itself in this predicament, then it probably behooves them to take a closer look at their backup architecture and determine exactly how much backup traffic is going across their corporate LAN.

The problem that can potentially emerge in a disk-based backup architecture is the corporate LAN can become a bottleneck when a backup server is directly attached to a virtual tape library (VTL). As backup data is sent by the backup agent on the application server to the VTL attached to the backup server, the data is piped through the application server, sent over a 1 Gb LAN connection and then funneled through the backup server to which the VTL is attached. So while the backup to the VTL attached to the backup server may complete successfully, going through all of these touch points can slow down the backup and introduce overhead on both the application and backup servers.

To address this situation, FalconStor recently announced its VTL Backup Accelerator that gives organizations a mechanism to address all three of these potential bottlenecks without requiring organizations to virtualize their storage infrastructure. The VTL Backup Accelerator works in the following way:

  • A light weight, low impact Backup Accelerator agent is installed on the application server. The Backup Accelerator agent can first complement and then replace the normal backup software agent on the server as it protects the data on the server.
  • A FalconStor Backup Accelerator appliance is installed on the corporate LAN. This appliance presents itself as an iSCSI target to the application server that has the Backup Accelerator agent installed on it. The Backup Accelerator agent on the application server discovers the iSCSI target, makes an initial copy of the application’s server data to the Backup Accelerator appliance and then copies all writes on the application server going forward to the Backup Accelerator.
  • A daily snapshot is created on the Backup Accelerator appliance. On a daily basis at a designated time or times, the Backup Accelerator agent will create application consistent snapshots on the Backup Accelerator appliance. This snapshot can then be presented to the backup server which can use it as the source for a backup at any time.

The attraction of this approach is two-fold. First, it eliminates the daily overhead that normally occurs on the application server when a backup takes place. While the copied writes do incur some overhead (FalconStor estimates that the performance overhead on the server is approximately 1 – 2%), many organizations will find this amount of overhead acceptable in light of the performance hit that backup jobs normally incur on the application server. Second, because a snapshot exists on the Backup Accelerator appliance, the backup server can grab this snapshot at any time and perform the backup. This eliminates the backup window which remains a concern among many organizations when it comes to backups.
Backup to disk
clearly solves many of the issues that organizations have with backup but they should not naively assume it solves all of them or that backup to disk overcomes the laws of physics – it does not. Introducing disk as a backup target and then running backups over the LAN may solve some but not all of the backup problems that organizations experience.

By taking snapshots and moving LAN-based backups to a VTL SAN infrastructure using FalconStor’s VTL Backup Accelerator, organizations can simultaneously move the processing associated with backups off of the application server while significantly accelerating backup time by moving the backup traffic to the FC SAN (4 or 8 Gb FC links). In so doing, organizations can realize the full benefits of disk-based backup for their LAN-attached servers without some of its hidden side effects that exist now.


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