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Media server load balancing
The need for backup software to do media server load balancing and failover is driven in part by the changing nature of backup loads and the need to continue doing backups when a media server is overloaded or fails. Veritas NetBackup 6.5's new Media Server Load Balancing feature creates a virtual pool of media servers. When a backup job starts, it's assigned to the least busy media server based on its CPU, memory, IO throughput and the number of active jobs. If a media server fails, new backup jobs are sent only to active media servers, while in-progress backup jobs are marked and automatically continue so another available media server doesn't need to restart the entire job.
Integrated support for the VMware VCB framework is also emerging as an important feature for integrated data protection. Although backup software agents can run individual virtual machines (VMs), running multiple backup jobs at the same time on the same VMware server consumes shared server CPU, memory and network resources, and creates system bottlenecks. The VCB framework supports a full backup of all of the data on the VMware server by backing up its Virtual Machine Disk Format (VMDK) file. However, VMDK file recoveries are an all-or-nothing proposition as they only restore the entire VMware and all of its VMs to a specific point-in-time (see "How backup vendors cope with
virtual servers," below).
|How backup vendors cope with virtual servers
Backup software vendors are taking advantage of the new file-level recovery feature supported by the VMware Consolidated Backup (VCB) framework. However, vendors are adding some specific options unique to their backup software to minimize the overhead associated with backing up VMware ESX servers.
EMC Corp. Avamar takes advantage of the VCB feature that allows a proxy server to mount a virtual machine (VM) on another VMware Infrastructure server running on a SAN. It provides the same deduplication benefits as when it runs on a local VM, while offloading the CPU utilization and backup times to the proxy backup server.
CommVault Galaxy Backup & Recovery provides two different recovery options using VCB: a VCB-proxy, full-image VM backup for disaster recovery that only works on SAN-based VMware ESX servers; and a VCB-proxy, file-level backup that does file-level restores for Windows-based clients.
IBM Corp. Tivoli Storage Manager 5.5 uses the VCB proxy server feature to coordinate the movement of VM data from the VCB proxy server to tape devices.
Symantec Corp. Veritas NetBackup for VMware, part of NetBackup 6.5's new Snapshot Client, enhances the granularity of recoveries. NetBackup 6.5 only does a single backup pass of the VMDK file, but can restore individual files or the full image (VMDK). Other backup software products typically require two passes to do a backup so they can do either file- or image-level restores.
This was first published in February 2008