Why do we always see Responder CQE Errors with RoCE RDMA?

Anyone who has configured and used SMB Direct with RoCE RDMA Mellanox cards appreciates the excellent diagnostic counters Mellanox provides for use with Windows Performance Monitor. They are instrumental when it comes to finding issues and verifying everything is working correctly.

Many have complained about the complexity of DCB configuration but in all earnest, any large network under congestion which needs specialized configurations has challenges due to scale. This is no different for DCB. You need the will to tackle the job at hand and do it right. Doing anything at scale reliable and consistent means automating it.  Lossless Ethernet, mandatory or not, requires DCB to shine. There is little other choice today until networking technology & newer hardware solutions take an evolutionary step forward. I hope to address this in a future article. But, this I not what we are going to discuss here. We’ve moved beyond that challenge. We’ll talk about one of the issues that confuse a lot of people.

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We’re not done yet. In part II we moved from the older CSP provider to a KSP provider but now we want to start issuing certs with a SHA256 hash. That’s what we’ll do here in part III.

Move from SHA1 to SHA256

The final step is that we move from SHA1 to SHA256 and tell the CA to work with the KSP. This is a tedious job that involves creating registry files in order to change the existing registry keys we already backed up before.

We’re not done yet. In part II we moved from the older CSP provider to a KSP provider but now we want to start issuing certs with a SHA256 hash. That’s what we’ll do here in part III.

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Move from a CSP to KSP provider

Once you have moved to a least Windows Server 2008 R2 you can take this step. Any version below doesn’t allow for this and should be considered the end of life. Many haven’t made the move from a CSP to KSP provider yet, even when they are already running Windows Server 2012 or 2012 R2 for a few reasons. There were some issues with older clients like Windows Server 2003 and Windows XP. These were fixed with a hotfix but in all seriousness, if you’re still on those OS versions you need to move a.s.a.p. and if not there’s nothing we can do to help you. A modern and secure PKI will be the last of your worries I’m afraid. For a Microsoft reference, see Migrating a Certification Authority Key from a Cryptographic Service Provider (CSP) to a Key Storage Provider (KSP).

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Introduction

Many Certificate Authority servers that were installed on Windows Server 2003 never got upgraded until Microsoft ceased the support of Windows 2003. Some of those are still out there running today. A massive amount of them got set up in an era when Wi-Fi in the SME market became very popular and CA servers were deployed to easily secure access to it. To be fair, a lot of administrators didn’t wait for Windows Server 2003 support to expire and made sure their CA was more or less up to date by upgrading them in place. That alone is something to commend. However, the operating system version only introduces the capability of using modern more secure providers and algorithms. It doesn’t upgrade the ones used by the PKI automatically for you. So many of these upgrade PKI servers are still using an old cryptographic provider, the “Microsoft Strong Cryptographic Provider” (SCP) and an old hash algorithm (SHA1) that’s been deprecated (see SHA1 Deprecation: What You Need to Know) or even banned.

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Introduction

In Windows Sever 2016 Microsoft improved Hyper-V backup to address many of the concerns mentioned in our previous Hyper-V backup challenges Windows Server 2016 needs to address:

• They avoid the need for agents by making the API’s remotely accessible. It’s all WMI calls directly to Hyper-V.
• They implemented their own CBT mechanism for Windows Server 2016 Hyper-V to reduce the amount of data that needs to be copied during every backup. This can be leveraged by any backup vendor and takes away the responsibility of creating CBT from the backup vendors. This makes it easier for them to support Hyper-V releases faster. This also avoids the need for inserting drivers into the IO path of the Hyper-V hosts. Sure the testing & certification still has to happen as all vendors now can be impacted by a bug MSFT introduced.
• They are no longer dependent on the host VSS infrastructure. This eliminates storage overhead as wells as the storage fabric IO overhead associated with performance issues when needing to use host level VSS snapshots on the entire LUN/CSV for even a single VM.
• This helps avoid the need for hardware VSS providers delivered by storage vendors and delivers better results with storage solution that don’t offer hardware providers.
• Storage vendors and backup vendors can still integrate this with their snapshots for speedy and easy backup and restores. But as the backup work at the VM level is separated from an (optional) host VSS snapshot the performance hit is less and the total duration significantly reduced.
• It’s efficient in regard to the number of data that needs to be copied to the backup target and stored there. This reduces capacity needed and for some vendors the almost hard dependency on deduplication to make it even feasible in regards to cost.
• These capabilities are available to anyone (backup vendors, storage vendors, home grown PowerShell scripts …) who wishes to leverage them and doesn’t prevent them from implementing synthetic full backups, merge backups as they age etc. It’s capable enough to allow great backup solutions to be built on top of it.

Let’s dive in together and take a closer look.

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Introduction

When we got Shared VHDX in Windows Server 2012 R2 we were quite pleased as it opened up the road to guest clustering (Failover clustering in virtual machines) without needing to break through the virtualization layer with iSCSI or virtual Fibre Channel (vFC).

First of all, you need to be aware of the limits of using a shared VHDX in Windows Server 2012 R2.

1. You cannot perform storage live migration
2. You cannot resize the VHDX online
3. You cannot do host based backups (i.e. you need to do in guest backups)
4. No support for checkpoints
5. No support for Hyper-V Replica

If you cannot live with these, that’s a good indicator this is not for you. But if you can, you should also take care of the potential redirected IO impact that can and will occur. This doesn’t mean it won’t work for you, but you need to know about it, design and build for it and test it realistically for your real life workloads.

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Why you should learn about SMB Direct, RDMA & lossless Ethernet for both networking & storage solutions

Server, Hypervisor, Storage

Too many people still perceive Windows Sever as “just” an operating system (OS). It’s so much more. It’s an OS, a hypervisor, a storage platform with a highly capable networking stack. Both virtualization and cloud computing are driving convergence of all the above these roles forward fast, with intent and purpose. We’ll position the technologies & designs that convergence requires and look at the implications of these for a better overall understanding of this trend.
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1. Introduction

With Windows Server 2016 we have gained some very welcome capabilities to do cost effective VDI deployments using all in box technologies. The main areas of improvement are in storage, RemoteFX and with Discrete Device Assignment for hardware pass-through to the VM. Let’s take a look at what’s possible now and think out loud on what solutions are possible as well as their benefits and drawbacks.

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Introduction

With Windows Server 2012 Hyper-V became truly NUMA aware.  A virtual NUMA topology is presented to the guest operating system. By default, the virtual NUMA topology is optimized by matching the NUMA topology of physical host. This enables Hyper-V to get the optimal performance for virtual machines with high performance, NUMA aware workloads where large numbers of vCPUs and lots of memory come into play. A great and well known example of this is SQL Server.

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Introduction

The need or perceived need for hard CPU processor affinity stems from a desire to offer the best possible guaranteed performance.  The use cases for this do exist but the problems they try to solve or the needs they try to meet might be better served by a different design or architecture such as dedicated hardware. This is especially true when this requirement is limited to a single or only a few virtual machines needing lots of resources and high performance that are mixed into an environment where maximum density is a requirement. In such cases, the loss of flexibility by the Hyper-V CPU scheduler in regards to selecting where to source the time slices of CPU cycles is detrimental. The high performance requirements of such VMs also means turning of NUMA spanning. Combining processor affinity and high performance with maximum virtual machine density is a complex order to fulfill, no matter what.

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