As organizations aggressively virtualize servers, backup becomes increasingly problematic. The benefits of higher server utilization and increased efficiency have a challenging side-effect, namely reducing the amount of physical resources available for CPU-intensive applications like backup.
The result is that backup windows are tightening in many shops, and users are forced to sacrifice recovery point objectives (RPO) or deploy more physical resources to accommodate backup requirements, thereby lowering the ROI impact of VMware. VMware Consolidated Backup (VCB) has been VMware’s answer – a central backup facility which is a backup proxy server, typically requiring additional physical resources and more storage space to avoid performing backups directly through the ESX host. VCB is deployed in less than 10% of VMware shops according to Wikibon estimates.
There is light at the end of the tunnel for practitioners, however. At the April 27th 2010 Wikibon Peer Incite Research Meeting, the community welcomed Henry Robinson of VMware, a Director of Product Management with responsibility for the vStorage API for Data Protection VADP. Also on the call was Peter Imming, a product manager for Backup Exec at Symantec. The community discussed VADP, how it improves the backup situation for VMware customers and how the VMware backup ecosystem is integrating using VADP.
Here are three slides submitted by Henry Robinson that we discussed on the call. Robinson took the Wikibon community through the following.
Figures 1 and 2: Evolution of VMware Backup
- Physical world uses shared backup server,
- Plenty of resources available for backup due to poor server utilization,
- Moving that structure to a virtual world causes immediate resource constraints,
- VMware introduces VCB - uses proxy server (often physical) to reduce VM load but not streamlined,
- VADP integrates backup through vStorage API's,
- Data transfers streamlined as backup apps read direct from VM backup removing a full transfer,
- Changed Block Tracking - CBT - keeps track of changes that have been made and allow for only changes to be backed up (once a full backup has taken place).
"Backup is one thing, recovery is everything" (Fred Moore). Restore is still evolving and two models are emerging:
- Restore of full image because a VM has been lost, and,
- Restore of a single file.
Bottom line. Son of VCB (VADP) is better but more work needs to be done to evolve recovery.
Figure 3: Ecosystem Partners Supporting VADP (as of 4/2010)
In addition, we discussed on the call data deduplication and how backup vendors are adding value in this regard. The dedupe debate has focused on the degree to which a customer is I/O bound and the degree to which source-side deduplication can eliminate backup bottlenecks. To the extent that source-side dedupe can be shown to eliminate I/O bottlenecks and increase ROI, the benefits are clear, however customers must rip and replace existing backup software.
Increasingly data deduplication is being offered at the source directly embedded into traditional backup software; although it's somewhat less mature than source-side products that have been on the market for years (e.g. Avamar). Nonetheless, the trends toward deduplication embedded within existing backup apps and the introduction of CBT ease the pressure on users to choose between rip and replace and lower ROI. Specifically, a combination of, for example, Symantec Backup Exec and Data Domain, can deliver much better ROI with VADP than it could with VCB because the I/O load is reduced.
The introduction of VADP allows practitioners to use existing backup infrastructure, consoles, and processes with the new capabilities found in the API such as CBT. The re-design of existing processes is fairly straightforward but is optimized for a vCenter view displaying vCenter console folders, avoiding the need to browse multiple machines.
There may still be benefits of re-architecting backup and moving to a new backup software model (i.e. rip and replace) to provide more granularity, even less I/O activity and perhaps some advantages on recovery, but VADP extends the value proposition for the existing backup software suppliers supporting the API.
The key is a backup application that exploits VADP and ideally CBT. Vendors can receive VADP certification and, as shown in Figure 3, currently six vendors have been VADP certified and more are expected later this year. With VADP and CBT, users can restore from latest incremental and work backwards in time from differentials to restore only necessary blocks.
Action Item: VMware backup has been a challenge for users with VMware consolidated backup providing a less than adequate solution. VADP addresses many of VCB's shortcomings especially with Changed Block Tracking (CBT). Users should push vendors for visibility on plans for VADP integration and plans to exploit emerging capabilities to reduce I/O loads and streamline backup.