Tag Archives: support

MS Exchange on Nutanix Acropolis Hypervisor (AHV)

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While Virtualization of MS Exchange is now common across multiple hypervisors it continues to be a hotly debated topic. The most common objections being cost (CAPEX), the next being complexity (which translates to CAPEX & OPEX) and the third being that virtualization adds minimal value as MS Exchange provides application level high availability. The other objection I hear is Virtualization isn’t supported, which always makes me laugh.

In my experience, the above objections are typically given in the context of a dedicated MS Exchange environment, which in that specific context some of the points have some truth, but the question becomes, how many customers run only MS Exchange? In my experience, None.

Customers I see typically run tens, hundreds even thousands of workloads in their datacenters so architecting silos for each application is what actually leads to cost & complexity when we think outside the box.

Since most customers have virtualization and want to remove silos in favour of a standarized platform, MS Exchange is just another Business Critical Application which needs to be considered.

Let’s discuss each of the common objections and how I believe Acropolis + Nutanix XCP addresses these challenges:

Microsoft Support for Virtualization

For some reason, there is a huge amount of FUD regarding Microsoft support for Virtualization (other than Hyper-V), but Nutanix + Acropolis is certified under the Microsoft Server Virtualization Validation Program (SVVP) and runs on block storage via iSCSI protocol, so Nutanix + Acropolis is 100% supported for MS Exchange as well as other workloads like Sharepoint & SQL.

Cost (CAPEX)

Unlike other hypervisors and management solutions, Acropolis and Acropolis Hypervisor (AHV) come free with every Nutanix node which eliminates the licensing cost for the virtualization layer.

Acropolis management components also do not require purchase or installation of Tier 1 database platforms, all required management components are built into the distributed platform and scaled automatically as clusters are expanded. As a result, even licenses for Windows operating system are not required.

As a result, Nutanix + Acropolis gives Exchange deployments all the Virtualization features (below) which provide benefits at no cost.

  • High Availability & Live Migration
  • Hardware abstraction
  • Performance monitoring
  • Centralized management

Complexity (CAPEX & OPEX)

Nutanix XCP + Acropolis can be deployed in a fully optimal configuration from out of the box to operational in less than 60 minutes. This includes all required management components which are automatically deployed as part of the Nutanix Controller VM (CVM). For single cluster environments, no design/installation is required for any management components, and for multiple-cluster environments, only a single virtual appliance (PRISM Central) is required for single pane of glass management across all clusters.

Acropolis gives Exchange deployments all the advantages of Virtualization without:

  • Complexity of deploying/maintaining of database server/s to support management components
  • Deployment of dedicated management clusters to house management workloads
  • Having onsite Subject Matter Experts (SMEs) in Virtualization platform/s

Virtualization adds minimal value

While applications such as Exchange have application level high availability, Virtualization can further improve resiliency and flexibility for the application while making better use of infrastructure investments.

The Nutanix XCP including Acropolis + Acropolis Hypervisor (AHV) ensures infrastructure is completely abstracted from the Operating System and Application allowing it to deliver a more highly available and resilient platform.

Microsoft advice is to limit the maximum compute resources per Exchange server to 24 CPU cores and 96GB RAM. However with CPU core counts continuing to increase, this may result in larger numbers of servers being purchased and maintained where an application specific silo is deployed. This would lead to increased datacenter and licensing costs not to mention operational overhead of managing more infrastructure. As a result, being able to run Exchange alongside other workloads in a mixed environment (where contention can easily be avoided) reduces the total cost of infrastructure while providing higher levels of availability to all workloads.

Virtualization allows Exchange servers to be sized for the current workload and resized quickly and easily if/when required which ensures oversizing is avoided.

Some of the benefits include:

  • Minimizing infrastructure in the datacenter
  • Increasing utilization and therefore value for money of infrastructure
  • Removal of application specific silos
  • Ability to upgrade/replace/performance maintenance on hardware with zero impact to application/s
  • Faster deployment of new Exchange servers
  • Increase availability and provide higher fault tolerance
  • Self-healing capabilities at the infrastructure layer to compliment application level high availability
  • Ability to increase Compute/Storage resources beyond that of the current underlying physical server (Nutanix node) e.g.: Add storage capacity/performance

The Nutanix XCP Advantages (for Exchange)

  • More usable capacity

With features such as In-Line compression giving between 1.3:1 and 1.7:1 capacity savings & Erasure Coding providing up to a further 60% usable capacity, Nutanix XCP can provide more usable capacity than RAW while providing protection from SSD/HDD and entire server failures.

In-Line compression also improved performance of the SATA drives, so its a Win/Win. Erasure coding (EC-X) stores data in a more efficient manner which allows more data to be served from the SSD tier, also a Win/Win.

  • More Messages/Day and/or Users per physical CPU core

With all Write I/O serviced by SSD the CPU WAIT time is significantly reduced which frees up the physical CPU to perform other activities rather than waiting for a slow SATA drive to respond. As MS Exchange is CPU intensive (especially from 2013 onwards) this means more Messages per Day and/or Users can be supported per MSR VM compared to physical servers.

  • Better user experience

As Nutanix XCP is a hybrid platform (SSD+SATA), newer/hotter data is serviced by the SSD tier which means faster response times for users AND less CPU WAIT which also helps further increase CPU efficiencies, again leading to more Messages/Day and/or Users per CPU core.

Summary:

With Cost (CAPEX), Complexity (CAPEX & OPEX) and supportability issues well and truly addressed and numerous clear value adds, running a business critical application like MS Exchange on Nutanix + Acropolis Hypervisor (AHV) will make a lot of sense for many customers.

Deduplication and MS Exchange

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Virtualization and Storage always seem to be a hot topics in regards to Exchange deployments and many of you would have seen my post Virtualizing Exchange on vSphere with NFS backed storage a while back.

This post was motivated by a tweet from fellow VCDX which stated:

dedupe not supported for Exchange, no we can’t turn it off.

Later in the twitter conversation he went on to say

To be clear not an MS employee, another integrator MS “master” certified. It’s the whole NFS thing again

I have heard similar over the years and for me the disappointing thing is the support statement is unclear as are the motivations behind support statements for Exchange in general. e.g.: Support for VMDK on NFS

The only support statement I am aware of regarding Exchange and deduplication is in the technet article “Exchange 2013 storage configuration options” under the section “Volume configurations for the Exchange 2013 Mailbox server role” at it states:

storageexchange

In the above statement which specifically refers to “a new technique to optimize storage utilization for Windows Server 2012” is states that for Stand-alone or High availability solutions de-duplication is not supported for Exchange database file unless the DB files are completely offline and used for backup or archives.

So the first question is “Is array level deduplication supported”?

There is nothing that says that it isn’t supported that I am aware of, so if you are aware of such a statement please let me know in the comments and I will update this post.

My interpretation of the support statement is that array level deduplication is supported and MS have simply called out that the deduplication in Windows 2012 is not. Regardless of if you agree or disagree with my interpretation, I think its safe to say the support statement should be clarified with justification.

The next question I would like to discuss is “Should deduplication be used with Exchange”?

Firstly we should discuss the fact Exchange can be deployed with Database Availability Groups (DAGs) which creates multiple copies of Exchange databases across up to 16 Exchange Mailbox (or Multi-Role) servers.

The purpose of a DAG is to provide high availability for the application and data.

So if the application is by design making duplicate copies, should the storage be undoing this work?

Before I give my opinion on deduplicating DAG copies, I want to be clear on two things:

1. Deduplication is a well proven technology which many different vendors implement either in-line or post process or in some cases both.

2. As array level deduplication is abstracted from the Guest OS and Application, there is no risk to the application such as data corruption or anything like that.

So back to deduplicating DAG copies.

I work for Nutanix and I wrote our best practice guide for Exchange which can be found below. In the guide, I recommended Compression but not deduplication. In an upcoming update of the document the recommendation remains to use compression but adds a further recommendation to use Erasure coding (EC-X) for data reduction.

Nutanix Best Practices Guide: Virtualizing Microsoft Exchange on Web-Scale Converged Infrastructure.

The reason for these recommendations is three fold:

1. Compression + EC-X give excellent data reduction savings for Exchange which generally result in usable capacity higher than RAW capacity while still providing data protection at the storage layer.

2. Deduplicating data which is deliberately written multiple times is a huge overhead on any infrastructure as data is still processed multiple times by the Guest OS, Storage Network and storage controller even if deplicate copies are not written to disk. To be clear, the Guest OS (CPU) and Storage network overhead are not eliminated by dedupe.

3. Nutanix recommends the use of hybrid nodes for Exchange with a small percentage of capacity provided by SSD (for all write I/O and hot data) and a large percentage of capacity provided by SATA. As a result the bulk of the data is stored on low cost SATA so the commercial benefit ($ per GB) of deduplication is minimal especially after compression and EC-X.

In my opinion deduplicating everything regardless of its profile is not the answer, so data reduction such as deduplication, compression and Erasure Coding should be able to be turned off for workloads which give minimal benefit.

For Exchange DAGs, deduplication should give excellent data reduction results in line with the number of DAG copies. So if an Exchange DAG has 4 copies, then approx 4:1 data reduction should be achieved right off the bat. Now this sounds great but when running a DAG on highly available shared storage (SAN/NAS/HCI) it is unnessasary to have 4 copies of data.

In reality, I recommend 2 copies when running on Nutanix because the shared storage provided by Nutanix keeps at least 1 additional copy (if using EC-X) or where using RF2 or RF3, 2 or 3 copies of data meaning in the event of a drive or node failure, the data is still available to the application without requiring a DAG failover. Similar is true when running Exchange on SAN/NAS/HCI solutions with some form of RAID or replication for data protection.

So the benefit of deduplication would therefore reduce to from possibly 4:1 down to 2:1 because only 2 DAG copies are really required if the storage is highly available.

Considering the data reduction from compression and storage solutions supporting Erasure Coding, I think deduplication is only commercially viable/required when using expensive all flash storage which lets face it, is not required for Exchange.

If you have chosen an all flash solution and you want to run all workloads on it and eliminate having silos of infrastructure for different workloads, then by all means deduplicate Exchange DAGs otherwise it will be a super expensive solution. But, in my opinion hybrid is still the best solution overall with the only real advantage of all flash being potentially higher and more consistent performance depending on many factors.

Summary:

I hope that Microsoft clarify their position regarding support for array level data reduction technologies including deduplication with detailed justifications.

I would be disappointed to see Microsoft come out and update the support policy stating deduplication (for array’s) is not supported as there is not technical reason it should not be supported (Happy to be corrected if credible evidence can be provided) regardless of if you think its a good idea or not.

Having worked in the storage industry for a long time, I have seen many different deduplication solutions used successfully with MS Exchange and I am yet to see any evidence that it is not a totally viable and enterprise grade option for Exchange databases.

The question which remains is, do you need to deduplicate Exchange databases? – My thinking is only where your using all flash systems and need to lower cost per GB.

My position being the better solution would be choose a hybrid solution when eliminating silos which gives you the best of all worlds and applications requiring all flash can have all flash and other workloads can use flash for hot data and lower cost SATA for cold storage or data which doesn’t require SSD (like Exchange).

Support for Active Directory on vSphere

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I heard something interested today from a customer, a storage vendor who sells predominantly block storage products was trying to tell them that Active Directory domain controllers are not supported on vSphere when using NFS datastores.

The context was the vendor was attempting to sell a traditional block based SAN, and they were trying to compete against Nutanix. The funny thing is, Nutanix supports block storage too, so it was a uneducated and pointless argument.

None the less, the topic of support for Active Directory on vSphere using NFS datastores is worth clarifying.

There are two Microsoft TechNet articles which cover support for  topic:

  1. Things to consider when you host Active Directory domain controllers in virtual hosting environments
  2. Support policy for Microsoft software that runs on non-Microsoft hardware virtualization software

Note: There is no mention of storage protocols (Block or File) in these articles.

The second article states:

for vendors who have Server Virtualization Validation Program (SVVP) validated solutions, Microsoft will support server operating systems subject to the Microsoft Support Lifecycle policy for its customers who have support agreements when the operating system runs virtualized on non-Microsoft hardware virtualization software.

VMware has validated vSphere as a SVVP solution which can be validated here: http://www.windowsservercatalog.com/svvp.aspx

The next interesting point is:

If the virtual hosting environment software correctly supports a SCSI emulation mode that supports forced unit access (FUA), un-buffered writes that Active Directory performs in this environment are passed to the host operating system. If forced unit access is not supported, you must disable the write cache on all volumes of the guest operating system that host the Active Directory database, the logs, and the checkpoint file.

Funnily enough, this is the same point for Exchange, but where the Exchange team decided not to support it, the wider organisation have a much more intelligent policy where they support SCSI emulation (ie: VMDKs on NFS datastores) as long as the storage ensures writes are not acknowledged to the OS prior to being written to persistent media (ie: Not volatile memory such as RAM).

This is a very reasonable support statement and one which has a solid technical justification.

In Summary, running Active Directory is supported on vSphere including both block (iSCSI, FC, FCoE) and file (NFS) based datastores where the storage vendor complies with the above requirements.

So check with your storage vendor to confirm if the storage your using is compliant.

Nutanix 100% complies with these requirements for both Block and File storage. For more details see: Ensuring Data Integrity with Nutanix – Part 2 – Forced Unit Access (FUA) & Write Through

For more information about how NFS datastores provide true block level storage to Virtual Machines via VMDKs, check out Emulation of the SCSI Protocol which shows how all native SCSI commands are honoured by VMDKs on NFS.

Related Articles:

  1. Running Domain Controllers in Hyper-V

This post covers the requirement for FUA the same as with vSphere and recommends the use of UPS (to ensure write integrity) as well as enterprise grade drives which are also applicable to vSphere deployments.