Previously on “The Backup Window,” I had described a scene that would rival a classic 1960s Batman cliffhanger. I was desperately trying to get my daughter dressed for church, so I could save my donut from the clutches of some Joker. Backup administrators tried to solve the Riddler’s question, “How can I protect all my VMs within my backup window?” As they looked at storage-based versioned replication, they worried that it would Freeze the flexibility of their virtualization environment. Fortunately, *Pow* *Zap* VMware Changed Block Tracking (CBT) was coming to the rescue.
However, despite its importance, CBT hasn’t generated the hype of Kim Kardashian’s wedding. (Google hits: VMware CBT – 2.2 million; Kim Kardashian Wedding – 18.5 million. I see you pretending not to know who Kim Kardashian is. Stop. You’re not fooling anybody. ) VMware CBT promotes versioned replication to become a first-class backup citizen. With VMware identifying the changed data, we can now build solutions that combine the best of storage-based-versioned replication with the best of the backup functionality.
- Minimal load on the client. The server tracks the changed blocks through the day; the client then reads only the changed blocks at backup time.
- Minimal load on the storage array. Reading only the changed data.
- Light network load. Deduplicating changed data further reduces the network load.
- Vendor lock-in. CBT works independent of storage array. Customers can back up VMs on any primary storage to any backup system that supports versioned replicas.
- Full functionality. The backup application or VM-specific protection tool provides the full backup workflows and functionality you have come to expect.
- Granularity of backup management. CBT works on a per-VM basis, so you can apply independent backup schedules, retention periods, security domains, etc. on each VM. More importantly, you can change those settings at any point, without penalty.
In short, you get the performance of versioned replication with the functionality, control and heterogeneity of backup.
What’s required to transform a technology like VMware CBT into a backup solution?
It’s bad enough trying to run recoveries from incremental file-based tape backups. Can you imagine the agony associated with trying to piece together something coherent from random series of blocks on tape? (Actually, I can – I watched the Tron sequel on cable this weekend. Yikes.)
Any viable CBT solution depends on a backup infrastructure built to manage changed-block versioned replicas, specifically:
- Dedupe backup software. Rapidly transform, catalog and index changed data into full backups to optimize for recovery reliability, simplicity and performance. You do not want software with “bolted-on” virtual synthetics to become a bottleneck or point of failure.
- Dedupe storage system. To store tens, hundreds or thousands of full backups, you need a storage system that can efficiently create and store those backups. As with any backup system, make sure that you can trust it as the storage of last resort and that you can manage each backup version independently.
By combining VMware CBT with the appropriate backup infrastructure, customers have not only been able to reduce their backup pain but also increase the amount and type of production load on their ESX servers. Of course, I don’t want to be a shameless product shill, so I’ll let you figure out what types of backup solutions can properly leverage VMware CBT. (Editor’s note: EMC is not too shameless to point out that Avamar 6.0 uses VMware CBT to deliver this ideal versioned replication solution to either an Avamar Data Store or Data Domain target.)
While both I and the rest of The Backup Window have focused on the value of VMware CBT, wise readers observe that this is merely one instance of this technique. Oracle Block Change Tracking, Microsoft filter drivers and storage-based versioned replicas highlight a broader industry trend. Backup software needs help from the primary data owners to scale. You want to bet on solutions that demonstrate a commitment to integrating with all those data owners. (Because you’d like your backup solution to last longer than a Kardashian marriage.)
In my next post, I will share some customer deployments in which the use of backup solutions with VMware CBT helped remove roadblocks to VM deployments while bringing storage and backup teams together, ultimately showing why making the right backup infrastructure choices does make a difference. So, tune in to the next blog post – same blog site, shorter backup window!
