NetBackup Accelerator vs. Simpana DASH Full

I want to start this blog with a note.

I mean no disrespect to CommVault as a company or its engineers innovating its products. Being an engineer myself by trade, I do understand that innovations are triggered by market demands and there is always room for improvements in any product. This blog is entirely my own opinions.

As most of you guys reading this blog know, I also write for official Symantec blogs. I recently got an opportunity to take readers of Symantec Connect on a deep dive into one of the major features in NetBackup 7.6 for VMware vSphere and vCloud environments. It is primarily targeted for users of NetBackup who knows its nuts and bolts. A couple of employees from a CommVault read the blog. It is natural in competitive intelligence world to look for weak spots or things that can be selectively pointed out to show parity. It is part of their job and I respect it. However it appeared that they wanted to claim parity for Simpana with NetBackup Accelerator for VMware based on two statements (tweets, to be precise!). While asking to elaborate, the discussion went on a rat hole with statements made out of context and downright unprofessional. Hence here I go with an attempt to compare Simpana 10 with NetBackup 7.6 on the very topic discussed in official blog.

Claims to equate parity with NetBackup Accelerator for VMware

  1. (Not explicitly stated) Simpana supports CBT
  2. Simpana had ‘block detection’ for over a year
  3. Simpana does synthetics

The attempt here is to check all the boxes to claim parity while at times people do miss the big picture! At times they were equating apples to oranges. Hence I am going to attempt to clarify this as much as possible using Simpana language for the benefit those two employees.

Simpana supports CBT: Of course, every major vendor supports it. It is an innovation from VMware. The willingness to support a feature from vStorage APIs is important to protect VMware virtual machines.

What sets NetBackup 7.6 apart from Simpana 10 in this case is that Simpana’s implementation of CBT is limited to recovering an entire VM or individual files from the VM. If you have enterprise applications (e.g. Microsoft Exchange, Microsoft SQL Server etc.), you must stream data through an agent inside the guest to protect those applications and perform granular recovery. The value of CBT is to minimize data processing and movement load on production VMs while performing backups. A virtual machine’s operating system binaries and related files are typically static and CBT won’t add much value there. The real value comes from daily changes to disk blocks by applications! That means ZERO value in Simpana to protect enterprise applications with its implementation of vSphere CBT.

Simpana had block detection for over a year,  Simpana does synthetics: The employee is trying to add a check box for Simpana next to NetBackup’s capability to make use of Symantec V-Ray to detect deleted blocks. Nice try!

First and foremost, the block optimization technique described in my blog is present in NetBackup since 2007, with version 6.5.1 when Symantec announced support for VMware Virtual Infrastructure 3. Congratulations on trying to claim that Simpana had this capability after half a decade! But wait…. We are talking about apple and orange here.

This technique had been available for both full and incremental backup schedules. It works no matter where backups are going to, disk, deduplicated disk, tape or cloud. NetBackup’s block optimization happens closer to the data source. Thus it detects deleted blocks at the backup host so that the deleted blocks never appear in SAN or LAN traffic to the backup storage. That is optimization for processing-power, interconnect-bandwidth and storage!

CommVault employee was in a hurry to equate this to something Simpana caught up recently.  This is what I believe he is referring to. (I am asking him to tweet back if there is anything else).  Quoted from Simpana 10 online documentation.

DASH Full is a read optimized Synthetic Full operation which does not require traditional full backups to be performed. Once the first full backup is completed, changed blocks are protected during incremental or differential backups. A DASH Full will run in place of traditional full or synthetic full. This operation does not require movement of data. It will simply update indexing information and the deduplication database signifying that a full backup has been completed. This will significantly reduce the time it takes to perform full backups.

There are so many things I want to say about this, but I am trying to be concise here with bullet points.

  • What Simpana has here is an equivalent of NetBackup OpenStorage Optimized Synthetics that was introduced in NetBackup 6.5.4 (in 2009). While NetBackup still supports this capability, Symantec had taken this to the next level with NetBackup Accelerator. For the record, NetBackup Accelerator is also backed by Optimized Synthetics and hence the so-called ‘block detection’ is there in NetBackup since 2009.
  • The optimization I was talking about was the capability to detect deleted blocks from the CBT data stream while CommVault is touting about data movement within backup storage!
  • The DASH full requires incremental backups and separate schedules for synthetic backups. NetBackup Accelerator eliminates this operational inefficiency by synthesizing full image inline using the resources needed for an incremental backup.
  • If you are curious about how NetBackup Accelerator in general is different from Optimized Synthetics (or DASH Full), this blog would help.
  • Last but not the least, did I say that NetBackup Accelerator for VMware works with enterprise applications as well? Thus both CBT and deleted blocks detection (both relevant to applications that does the real work inside VM) adds real value for NetBackup Accelerator

What’s up with VADP backups and VDDK on vSphere 5.1?

VMware vSphere 5.1 has been in the market for more than a few months now and the interest in the new capabilities is high. Because of this the market saw many backup vendors rush to announce support for vSphere 5.1 in their VADP (vStorage APIs for Data Protection) integration. Everything looked clean and shiny and new.

On November 21, Symantec made an interesting announcement1. In a nutshell, the statement was that support for vSphere 5.1 would be delayed in its NetBackup and Backup Exec products. It was because they discovered issues while testing the VADP 5.1 API for integration. The API in the current form may introduce risk in performing consistent backups and ensuring reliable restores. All vendors receive the same API, not all vendors perform the same level of testing.

In order to explain the intricacies, first we need to take a quick look at how a backup product is integrated with VMware vSphere. With each release of vSphere, VMware publishes a set of APIs known as VMware APIs for Data Protection or VADP. One of the key components of VADP is Virtual Disk Development kit aka VDDK. This is the component through which third party code receives authenticated access to vSphere Datastores and virtual machine disk files. VMware makes this component available to its technology partners. Partners (backup product vendors in this case) ship this along with their product that has calls to vStorage APIs.

With each version of vSphere, an equivalent version of VDDK is released. The VDDK is generally backward compatible to one or more earlier versions of vSphere. For example, VDDK 5.1 supports2 vSphere 5.1, 5.0 and 4.1. VDDK 5.0 supports3 vSphere 5.0, 4.1, 4.0 and VI 3.5. Since the updated VDDK is required to understand the modified data structures in a new version of vSphere, lower versions of VDDK are in general not supported for accessing a higher version of vSphere. For example, VMware historically and currently (as of today) does not support the use of VDDK 5.0 to access datastores in vSphere 5.1.  VMware documents supported versions of vSphere for each of its VDDK versions in release notes.

The key to remember is the statement in bold face above. VMware does not support any violated combinations because of the risks and uncertainties. The partners are expected to ship the correct version of VDDK when they announce the availability of support for a given vSphere release.

What Symantec announced and VMware confirmed4 is that VDDK 5.1 has issues and hence the support for vSphere 5.1 in its products will be delayed. This makes sense since VDDK 5.1 is the only version currently allowed to access vSphere 5.1. The face-saving reactions from other vendors to this announcement revealed some of the dirty games and ugly truths to come out in the area of VADP/VDDK integration.

 

  1. Vendors were claiming support for vSphere 5.1 but still shipping VDDK 5.0 with their products. This is currently not supported by VMware because of the uncertainties.  This may change but at the time vendors claiming support, they were taking risks that typically are not acceptable in field of data protection business.
  2. Vendors were mucking with API calls and silently killing hung processes. That may work for an isolated or random hang. But will not work when there are repeatable hang situations like those observed in VDDK 5.1. Plus, there are performance and reliability concerns in abruptly ending sessions with vSphere.
  3. Most vendors weren’t testing all the edge cases and never realized the problems in VDDK 5.1, thus prematurely announcing support for 5.1

 

If your backup vendor currently supports vSphere 5.1, be sure to ask what their situation is.

Sources and references:

1. Quality wins every time: vSphere 5.1 support update, Symantec official blog.

2. VDDK 5.1 Release Notes, VMware Support resources

3. VDDK 5.0 Release Notes, VMware Support resources

4. Third-party backup software using VDDK 5.1 may encounter backup/restore failures, VMware Support KB