NVM Express over Fabrics

Any technologist who’s read, let alone used NVM Express (NVMe), is pretty enthusiastic about it’s capabilities and if it was not for availability and financial restrictions we’d all have at least a couple in our home systems and labs. It seems to succeed very well in making sure the host can keep up with the performance (low latencies, high throughput)) delivered by SSD drives than our current interfaces.

This means that many are very happy with future visions on how PCIe will dislodge SAS/SATA as the preferred SSD interface. This might seem feasible for local storage right now but how to deal with this in an actual storage array, what if we want to size this to a larger scale? There are no “PCIe JBODS”. So what does one do? Well, how did we do it in the past with FC? We created a fabric. Below we see several local & remote NVMe architectures even hybrid ones with traditional SAS.


That’s exactly what NVM Express Inc. is doing, creating the specs for a fabric. This holds the promise to achieve superior results due to the elimination of SCSI translation which reduces latency significantly by delivering NVMe end to end. Not only that but we also see the following efforts in the NVM Express Specification 1.2 to give it enterprise grade capabilities beyond pure performance.

  • Enhanced status reporting
  • Expanded capabilities including live firmware updates

There have been some early demos of NVMe over Fabrics mainly focusing on the “remote” performance. While local NVMe SSDs have the edge on absolute IOPS the difference with NVMe over a fabric is not significant. The reduction in latency is measured in < 10 µs,so that’s good news. The fabric leverages RDMA (yes, yet another reason that my time spending with this technology has been a useful investment). This can be Infiniband, RoCE or iWarp. There’s also the new kid on the block “Intel Omni Scale”  (even if their early demo used iWARP). There’s also a Mellanox RoCE demo.


Now with NVMe SSD disk speeds it seems that the writing is on the wall that ever better fabric performance will be needed to support the tremendous throughput this evolution of storage can deliver. RDMA seems poised for success in regards to this. Now, yes, strictly speaking the NVMe traffic does not require RDMA but let’s just say I don’t see anyone building it without. I also think this means even iWarp fabrics will use DCB (PFC) to make sure we have a lossless network. The amount of traffics will be immense and why not optimize for the best possible performance? I hold the opinion this is beneficial for east-west traffic today in larger environments, especially when in converged networks. Unless the Intel® Omni-Path Architecture blows everyone else away that is Smile. Too early to tell.

Now does this dictate the total and absolute obsolescence of iSCSI and FC? No. There is no reason why a NVMe Fabrics storage solution cannot offer storage to hosts via FC, iSCSI, SMB 3, NFS, FCoE, … They, potentially could even offer iWarp, RoCE or Infiniband to the hosts so you won’t lose your prior investments or get locked into one. I have no magic ball so I cannot tell you if this will happen. What I do now that when it comes to MPIO versus multichannel for load balancing and even failover and recovery, multichannel sometimes does a (far?) superior job in my honest opinion especially with older hypervisors even when the hypervisor uses separate sessions per virtual machine to achieve better load balancing over iSCSI or the like. Anyway, I digress. One thing I do know is that I’ll keep a keen eye on what Microsoft is doing in this space, especially in regards to Windows Server 2016. It’s time to up the level on scalability & support for newer technologies once again.


Changing the segment size of a virtual disk in PowerVault MD Storage Series

It happens to the best of us, sometime we selected the wrong option during deployment and or configuration of our original virtual disks. Or, even with the best of planning, the realities and use cases of your storage changes so the original choice might not be the most optimal one. Luckily on a DELL MD PowerVault storage device you do not need to delete the virtual disk or disks and lose your data to reconfigure the segments size. Even better is that you can do this online as a background process., which is a must at it can take a very long time and it would cause prohibitively long down time if you had to take the data off line for that amount of time.


You have a certain control over the speed at which this happens via the priority setting but do realize that this takes a (very) long time. Due to the fact it’s a background process you can keep working. I have noticed little to none impact on performance but you mileage may vary.



How long does it take? Hard to predict. This is a screenshot of two 50TB virtual disks were the segment size is being adjusted on line …


You cannot always go to the desired segment size in one step. Sometime you have only an intermediate size available. This is the case in the example below.


The trick is to first move to that segment size and then repeat the process to reach the size you require.  In this case we’ll first move to 256 KB and than to 512 KB segment size. So this again take a long time. But again, it all happens on line.

In conclusion, it’s great to have this capability. When you need to change the size when there is already data on the PowerVault virtual disks you have the ability to do so online while the data remains available. That this can require multiple steps and take a long time is not a huge deal. You kick it off and let it run. No need to sit there and watch it.

Handy DELL Storage Tool: Dell Virtual rack

If you need to see and find information on DELL storage fast they have a nice page on line with a virtual rack where you can look at the components of their various storage offerings.


They update it regularly and it’s a fast and easy way to get started. Naturally you’ll need to dive in a bit deeper or get some help to work out the last details. I’m like the Compellent as I have found it to be the best possible traditional storage solution for a Windows Server 2012 R2 Hyper-V environment and great value for money. I hope they can find a way to keep delivering that same value in the coming years in an ever changing storage landscape.

Storage Replication – Server To Server Demo

I’ve discussed the efforts Microsoft is putting into enhancing the storage offerings (Storage Spaces, SOFS, SMB) in its OS since Windows Server 2012 (R2) before in previous articles. In my last blog post on this subject  Microsoft Keeps Investing In Storage Big Time I talked about their latest announcements around storage replica in the Windows Server Technical Preview.

In this post I’d like to show case how to set up server to server storage replication and demonstrate how to recover from certain events.  We are doing this asynchronously as the scenario is one were we replicate a backup target off site to another city. Not an uncommon scenario and one that gives copies off site without introducing the cost & operational overhead of portable media.clip_image002

The easiest way to show  this without writing elaborate white papers is a video. I’ll wait with more elaborate writings or demo videos as things are bound to change a lot prior to RTM. After all we still only have the more then 3 month old Technical Preview bits. It’s important to realize what we are now getting in box with Windows Server aka the Cloud OS that used to require 3rd party solutions.

I hope to be doing some talks & presentations on this subject and in good tradition make those presentations demo heavy as I like to really show how technology in action.

VEEAM Invests in Faster & More Efficient Data Protection With Backup & Replication 8

Ever more data to protect without breaking the systems or the bank

One of my major concerns today in IT, weather it is on premises or in the cloud, is the cost, time, reliability and feasibility of backup and restores. This true for most of us. Due to the environments in which I deliver my services my main issue with backups is the quantity of data. The amount of data is staggering and growth is not showing a downward trend.

The big four: CPU, Memory, Network & Storage

Over the years we have seen a vast increase in compute, memory, network and storage capabilities and pricing. CPUs are up to 18 cores per socket as I write this. DDR4 memory is here and the cost is relatively low. We have affordable 10Gbps networking to throw at the problem as well or in some case 8 to 16Gbps Fibre Channel. So when it comes to CPU, memory and network we’re pretty well served.

Storage is evolving as well and we’re getting ever bigger and, if you have the budget that is, faster storage arrays in different flavors. But it remains a challenge. First of all to get the right amount of IOPS and storage capacity at an affordable price point is a balancing act. Secondly when dealing with backups we need to manage the source IOPS & latency against the target. But that’s not all, while you might want to squeeze every last IOPS & 1ms latency out of your backup target you can’t carelessly do that to your source storage. If you do, this might constitute a Denial Of Service attack against your applications and services. Even today storage QoS is either non existent, in it’s infancy or at best limited to particular workloads on storage solutions.

The force multiplier: Backup software capabilities & approaches

If you’ve made sure the above 4 resources are not your killer bottle neck the backup software, methods algorithms and the approach used will be either your biggest problem or you best friends. You need your backup software to be:

  • Capable
  • Scalable
  • Fast
  • Configurable
  • Scale Out

There are some challenging environments out there. To deal with this backup software should be able to leverage the wealth of capabilities compute, network, memory & storage are offering to protect large amounts of data reliable and fast. This should be done smart and in an operationally supportable manner. VEEAM has been working on this for a long time and they keep getting better at this with every release and it allows for scale out designs in regards to backups targets.

VEEAM Backup & Replication 8.0

There are many improvements in v8 but a couple stand out.


Consistency groups (Hyper-V)

Backup jobs can execute more than one VM backup task simultaneously from the same volume snapshot with “Allow Processing of Multiple VMs with a single volume snapshot”.


This means you can reduce the number of snapshots significantly where in the past you needed a volume snapshot per VM. VEEAM limits the the maximum amount of VMs you can backup per snapshot to 4 when using software VSS and to eight with hardware VSS. They do this because under heavy load VSS/CSV sometimes has issues. This number can be tweaked to fit your needs (no all environments are created equally) with 2 registry values under HKLM\SOFTWARE\Veeam\Veeam Backup and Replication key:

  • MaxVmCountOnHvSoftSnapshot (DWORD)
  • MaxVmCountOnHvHardSnapshot (DWORD) registry values

Reducing the number of snapshots to be taken is good as it saves resources, speeds up things & as VSS can be finicky, not needing more than absolutely necessary is a good thing.

Backup I/O Control.

Another improvement is backup I/O Control which delivers capability to dynamically adjust the number of backup tasks based on IOPS latency. Under Options you’ll find a new Tabbed sheet, I/O Control. It contains the parallel processing option that used to be under “Advanced” tab in Veeam B&R 7.


The idea is to move to a more “policy driven” approach for handling the load backups can put on the storage. Until now we’d configure a number of X amounts of tasks to run against the source storage in order to keep IOPS/Latency in check. But this is very static and in a dynamic / elastic “cloud” world this isn’t very flexible nor is it feasible to keep tuned to the best number for the current workload.

I/O Control let’s you set limits on how much latency is acceptable for your data stores. Removing or adding VMs to the data store won’t invalidate your carefully set number of tasks allowed as it’s now the latency that’s used to dynamically tune that number for you.

I/O control has two settings:

 “Stop assigning new tasks to datastore at: X ms” :VEEAM looks at the latency (IOPS) before assigning a proxy (backup target) to a virtual disk or won’t launch the task until the load has dropped.  This prevents the depletion of IOPS by launching to many backups.

“Throttle I/O of existing tasks at: Y ms”: This will throttle the IO of already running  backup jobs when needed due to some application workloads in the VMs running on the source storage kicking in. The backups will be throttled so they’ll take longer but they won’t kill the performance of the applications while they are running.

These two setting allow for the dynamic and on the fly tweaking of the number of backups tasks running as well as their impact on the storage performance. Once you have determined what latency values are acceptable to you you’re done, VEEAM handles the tweaking for you. The default values seems to reflect industry best practices (sustained > 20 ms is considered problematic)

The below screenshot is for the backup job log and shows latency being monitoredclip_image002

With VEEMA B&R v8 Enterprise + You can even do this per data store, meaning you can optimize this per backup source. This recognizes that is no “one sizes fits all perfectly” and allows for differentiation. Yet it does so in a way that does not compromise on the simplicity of use that VEEAM offers. This sounds easy but from experience I know this isn’t. VEEAM manages to offer a great balance between simplicity and functionality for companies of all sizes.

Select “Configure”


In the “Datastore Latency Settings” you can add one, more or all data store you are protecting with VEEAM. This allows for differentiation when you have CSV that are used for SQL Server VMs versus stateless web servers of or other workloads that are not storage I/O intensive.


Select the datastore (in our case the CSV volumes in Hyper-V Cluster)


By selecting the desired datastore and clicking “Edit”  you can individually adjust the settings for that datastore.



It looks like we have some great additional capabilities in an already very good solution. I’ll be using these new capabilities in real life scenarios to see how these work out for us and optimize the backups of the virtualized environment under my care. Hardware VSS Providers, SANs, CSV’s normally need some tweaking and care to make them run well, so that’s what we’ll be doing.

The Hyper V Amigos Showcast Episode 6: Storage Spaces

Everybody is very busy and I’m a bit tires but here’s the 6th episode of the Hyper-V Amigos show cast. In this episode we get to play a bit with storage spaces in Carsten’s lab.

As always we had a lot of fun doing so and thanks to Carsten Rachfahl and the assistance of Kerstin (his charming wife, also an MVP, in Office 365) we could simulate hardware failures & film them for you!


Carsten & I discuss several scenarios and what’s happening during failovers. Carsten is assisting customers with this a lot so he has some of the most varied experience with storage spaces and SOFS out there!  Interesting stuff and for people who haven’t even looked at Windows Server 2012 or later yet a wake up call to start as the world is not limited to what we once knew. It’s not your daddy’s Windows anymore Winking smile

I hope you enjoy it and we’re already planning for the next one!

Microsoft Keeps Investing In Storage Big Time

Disclaimer: These are my musing on the limited info available about Windows Server vNext and based on the Technical Preview bits at the time of writing. So it’s not set in stone & has a time limited value.

Reading the documentation that’s already available on vNext of Windows it’s clear that Microsoft is continuing it’s push towards the software defined data center. They are also pushing high to continuous availability ever more towards the  “continuous” side of things.

It’s early days yet and we just only downloaded the Technical Preview but what do we read in What’s New in Storage Services in Windows Server Technical Preview

Storage Quality of Service

  • They are giving us more Storage Quality of Service tied into the use of SOFS as storage over SMB3. As way to many NAS solutions don’t support SMB3 or only partially (in a restricted way) it’s clear too me that self build SOFS solution on a couple of servers is and remains the best SMB3 implementation on the market and has just gotten storage QoS.

Little Rant here: To the people that claim that this is not capable of high performance, I usually laugh. Have you actually build a SOFS or TFFS with 10Gbps networking on modern enterprise grade servers line the DELL R720 or 730? Did you look at the results form that relative low cost investment? I think not, really. And if you did and found it lacking, I’ll be very impressed of the workload you’re running.  You’ll force your storage to the knees earlier than your Windows file server nowadays.

  • It’s in the SOFS layer, so this does not tie you into to Storage Space if you’re not ready for that yet but would like the benefits of SOFS. As long as you have shared storage behind the SOFS you’re good.
  • It’s policy based and can apply to virtual machines, groups of virtual machines a service or a tenant
  • The virtual disk is the level where the policy is set & enforced.
  • Storage performance will dynamically adjust to meet the policies & when tied the performance will be fairly distributed.
  • You can monitor all this.

It’s right there in the OS.

Storage Replica

This gives us “storage-agnostic, block-level, synchronous replication between servers for disaster recovery, as well as stretching of a failover cluster for high availability. Synchronous replication enables mirroring of data in physical sites with crash-consistent volumes ensuring zero data loss at the file system level. Asynchronous replication allows site extension beyond metropolitan ranges with the possibility of data loss.”

Look for Hyper-V we already had Hyper-V replica (which is also being improved), but for other workloads we still rely on the storage vendors or 3rd party solutions. But now I can have my storage replicas for service protection and continuity out of the box with Windows.  WOW!

and as we read on ..

  • Provide an all-Microsoft disaster recovery solution for planned and unplanned outages of mission-critical workloads.
  • Use SMB3 transport with proven reliability, scalability, and performance.
  • Stretch clusters to metropolitan distances.
    Use Microsoft software end to end for storage and clustering, such as Hyper-V, Storage Replica, Storage Spaces, Cluster, Scale-Out File Server, SMB3, Deduplication, and ReFS/NTFS.
  • Help reduce cost and complexity as follows:

Hardware agnostic, with no requirement to immediately abandon legacy storage such as SANs.

Allows commodity storage and networking technologies.
Features ease of graphical management for individual nodes and clusters through Failover Cluster Manager and Microsoft Azure Site Recovery.

Includes comprehensive, large-scale scripting options through Windows PowerShell.

  • Helps reduce downtime, and increase reliability and productivity intrinsic to Windows.
  • Provide supportability, performance metrics, and diagnostic capabilities.

I have gotten this to work in the lab with some trial and error but this is the Technical Preview, not a finish product. If they continue along this path I’m pretty confident we’ll have functional & operational viable solution by RTM. Just think about the possibilities this brings!

Storage Spaces

Now I have not read much on Storage Space in vNext yet but I think its safe to assume we’ll see major improvements there as well. Which leads me to reaffirm my blog posy here: TechEd 2013 Revelations for Storage Vendors as the Future of Storage lies With Windows 2012 R2

Microsoft is delivering more & great software defined storage inbox. This means cost effective yet very functional storage solutions. On top of that they put pressure on the market to deliver more value if they want to stay competitive. As a customer, whatever solution fits my needs the best, I welcome that. And as a consumer of large amounts of storage in a world where we need to spend the money where it matters most I like what I’m seeing.

Tip for Microsoft: configurability, reliability and EASY diagnostics and remediation are paramount to success. Sure some storage vendor solution aren’t to great on that front either but some are awesome. Make sure your in the awesome category. Make it a great user experience from start to finish in both deployment and operations.

Tip for you: If you’re not ready for prime time with Storage Spaces , SMB Direct etc … do what I’ve done. Use it where it doesn’t kill you if you hit some learning curves. What about storage spaces as a backup target where you can now replicate the backups of to your disaster recovery site?