Hyper-V and vSphere storage APIs: Tailoring your virtual environment
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Virtual servers have changed the backup game. Originally, as virtual servers arrived in the data center, administrators
backed them up like they did regular physical servers, using a backup software agent for each VM. But given the number of VMs that could be put onto an ESX host, this had the potential to create a real bottleneck with dozens of backups coming from a single server.
VMware responded with VMware Consolidated Backup (VCB), a module that runs on a proxy backup server, collects snapshots of each VM’s disk image and is then itself backed up. VCB was an improvement over traditional backup and, according to Storage magazine’s Spring 2011 Purchasing Intentions survey, it has seen significant adoption. But, in addition to requiring a separate server (the proxy), it’s had some implementation problems.
The vStorage APIs for Data Protection (VADP) are essentially the next generation of VCB, replacing VCB in vSphere 4. Besides eliminating the proxy server, VMware VADP integrates with the backup application software and adds some important features. Using VADP, the backup application triggers the API to kick off the snapshot process and then backs up the resulting data set by mounting the snapshot and storing the data like a regular client. This allows the backup software to essentially take image-level backups of VMs directly and manages them as it would any other client.
VADP includes a feature called Changed Block Tracking (CBT), which monitors the data blocks that have changed since the last backup was completed. Previously, the entire VM image would have had to be backed up each cycle, like running a full backup, regardless of how much data was new. Results from the spring Storage magazine Purchasing Intentions survey would seem to indicate this is an issue as “Back up too much” was given as the No. 1 problem in backing up virtual servers.
CBT keeps track of the blocks when they change and allows the backup application to query the VMkernel to determine which blocks are candidates for backup. Like running an incremental backup in traditional backup applications, this block-level, change tracking feature reduces the backup window substantially. It can also eliminate the need in other processes, like changed-based replication, to run separate scans of the backup set to determine which blocks need to be handled. Overall, VADP essentially virtualizes what was a physical backup process and allows it to be embedded into an existing third-party backup application. It’s supported by all the major backup software vendors.
Opportunity and risk for VARs
It’s always surprising to find out how many companies are doing things the same old way, even when there may be a better solution available. Backups are a great example, as supported by Storage magazine’s Purchasing Intentions survey, in which about a third of 362 survey respondents reported using traditional methods for backing up virtual servers.This could simply be a case of “if it ain’t broke, don’t fix it,” as companies certainly have other things on the IT projects whiteboard to attend to.
But for many, backing up tens or hundreds of VMs with separate backup agents is not only expensive (buying backup licenses), but it may also be a waste of resources and time. For companies running a backup app that supports it, VADP could be just what they need.
This technology presents an opportunity for VARs but also a potential risk. The opportunity is to bring this functionality into accounts that are using a backup product you sell (but aren’t buying from you) and ask them why they’re not on VADP. Backup is still a task that most IT organizations associate with at least a little pain, in some cases a lot of pain. This makes it an ideal topic to ask about when you’re in a prospecting conversation. Chances are you’ll get a positive response, and it could lead to the first project in a VMware campaign at a new account.
On the other side of the coin, VMware backup represents a vulnerability in accounts that are already your customers for backup infrastructure. If another VAR starts asking about VADP, this could create a problem -- unless you have already enlightened the customer. Also, VADP may reduce the amount of software your customers need, since it doesn’t require a separate client license for each VM, although many still require agents for specific applications. But like so many other examples, saving customers money is never a bad strategy, even if it does reduce your sales numbers in the short run.
Traditional backup applications have been around for years, consuming an enormous volume of resources with what is arguably an inefficient process. No other application handles as much data or creates as many redundant copies (even with deduplication). Image-based backups are the exception. Taking an initial snapshot of a VM and using an incremental process to update it is very resource-efficient and can significantly reduce the backup window.
In addition to VADP, several companies have come out with data protection products designed specifically for VMware and the other server virtualization platforms. Some of these products have the ability to restart backed-up VMs directly from the backup space, without first restoring them, or use physical-to-virtual conversion to provide better backups to nonvirtualized servers. Once your customer gets used to snapshot and image-level backups, they may be less interested in the traditional backup products that you have been selling them. So while understanding VADP is essential for a VAR in the backup space, be aware that it may mean “letting the genie out of the bottle.”
Eric Slack is a senior analyst with Storage Switzerland.