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VStorage API support focus of Symantec-Veeam battle

Veeam Software disagrees with Symantec's claim that issues with the VMware vStorage 5.1 API makes third-party support impossible pending fixes.

Backup software leader Symantec and virtual machine backup specialist Veeam Software are sparring over whether data protection can be safely supported with VMware's vStorage 5.1 API. A Symantec blog claimed that issues with the application programming interface can cause backup and restores to fail or hang, while Veeam counters that it already solved those problems in its software.

Drew Meyer, Symantec's director of marketing for Backup Exec, wrote a blog post last Wednesday pointing out that Symantec ran into issues while testing the vStorage 5.1 application programming interface (API). Meyer claimed these issues "introduce risk [in] performing consistent backups and ensuring reliable restores." Writing on behalf of the Backup Exec and NetBackup teams, Meyer added that VMware documented the problems in the vSphere 5.1 release notes, and Symantec will re-test after VMware updates the vStorage API.

Meyer went on to question the validity of any backup vendor who claims to support backups for the vStorage 5.1 API.

"We can only conclude that compatibility and support claims from other vendors are either poorly informed or possibly represent a more cavalier 'ship-and-fix' data protection approach than Symantec is willing to accept," Meyer wrote.

Veeam's Vice President of Product Strategy Doug Hazelman took that as a shot at Veeam because it claims full vSphere 5.1 support for its Backup & Replication application. Hazelman wrote a counter blog on the issue Monday, charging that the vSphere 5.1 problems that Symantec found were specific to Symantec software. He accused Symantec of trying to scare and mislead VMware customers about backups with vSphere 5.1.

Hazelman wrote that the vSphere backup problems have been around in previous versions of the API, but Veeam's software was designed to handle the problems. He pointed the finger at Backup Exec and NetBackup. "All customers who are using Symantec backup products are potentially at risk," Hazelman wrote.

VStorage APIs for Data Protection (VADP) were added with vSphere 4 to help improve backup by allowing backup vendors to integrate the process with vSphere.

Meyer pointed out problems listed in the vSphere 5.1 Virtual Disk Development Kit (VDDK) release notes, which included: occasional segmentation-violation crashes during library disconnect; Windows processes can hang during connect or cleanup while loading or unloading libraries because of intermittent race condition; and Disk Open fails without an SSL thumbprint from vCenter.

VMware's release notes said fixes will be available in the VDDK 5.1's first update. The first two problems were among issues reported after the vSphere upgrade in October. The Disk Open issue, which can occur when vCenter Server 5.1 manages virtual disk on the ESXi 5.0 hypervisor and older hosts, was discovered after the vSphere 5.1 release.

Hazelman wrote that Veeam discovered the vSphere backup problems early during its testing of VADP. The vendor designed its software to work around the VDDK problems by separating the VDDK calls into a separate process monitored by a watchdog process to increase reliability, he added.

"In case the process hangs, we simply kill the process without affecting the job," he wrote. "With an alternative architecture not featuring such isolation, VDDK code hang will cause the whole backup and restore job to hang." He wrote that Veeam also sets extra timeouts on critical VDDK calls to avoid possible deadlocks.

If you are using vSphere 5.1 or considering an upgrade, it's worth checking out the VDDK 5.1 release notes Meyer refers to, as well as this VMware Knowledge Base article.

The hard feelings between Symantec and Veeam are not new. Symantec filed a lawsuit against Veeam and Acronis last February for patent infringement, claiming the two smaller competitors used its technology in their products.

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