Yellow Bricks

by Duncan Epping

vplex

New whitepaper available: vSphere Metro Storage Cluster Recommended Practices (6.5 update)

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I had many requests for an updated version of this paper, so the past couple of weeks I have been working hard. The paper was outdated as it was last updated around the vSphere 6.0 timeframe, and it was only a minor update. I looked at every single section and added in new statements and guidance around vSphere HA Restart Priority for instance. So for those running a vSphere Metro Storage Cluster / Stretched Cluster of some kind, please read the brand new vSphere Metro Storage Cluster Recommended Practices (6.5 update) white paper.

It is available on storagehub.vmware.com in PDF and for reading within your browser. Any questions and comments, please do not hesitate to leave them here.

 

SMP-FT and (any type of) stretched storage support

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I had a question today around support for SMP-FT in an EMC VPLEX environment. It is well known that SMP-FT isn’t supported in a stretched VSAN environment, but what about other types of stretched storage? Is that a VSAN specific constraint? (Legacy) FT appears to be supported for VPLEX and other types of stretched storage?

SMP-FT is not supported in a vSphere Metro Storage Cluster environment either! This has not been qualified yet, I’ve requested the FT team to at least put it up on the roadmap and document max latency tolerated for these types of environments for SMP-FT just in case someone would want to use it in a campus situations for instance, despite the high bandwidth requirements for SMP-FT. Note that “legacy FT” can be used with vMSC environment, but not with VSAN. In order to use legacy FT (single vCPU) you will need to use an advanced VM setting: vm.uselegacyft. Make sure to set this setting when using FT in a stretched environment!

High latency VPLEX configuration and vMotion optimization

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This week someone asked me about an advanced setting to optimize vMotion for VPLEX configurations. This person referred to the vSphere 5.5 Performance Best Practices paper and more explicitly the following section:

Add the VMX option (extension.converttonew = “FALSE”) to virtual machine’s .vmx files. This option optimizes the opening of virtual disks during virtual machine power-on and thereby reduces switch-over time during vMotion. While this option can also be used in other situations, it is particularly helpful on VPLEX Metro deployments.

I had personally never heard of this advanced setting and I did some searches both internally and externally and couldn’t find any references other than in the vSphere 5.5 Performance paper. Strange, as you could expect with a generic recommendation like the above that it would be mentioned at least in 1 or 2 other spots. I reached out to one of the vMotion engineers and after going back and forth I figured out what the setting is for and when it should be used.

During testing with VPLEX and VMs using dozens of VMDKs in a “high latency” situation it could take longer than expected before the switchover between hosts had happened. First of all, when I say “high latency” we are talking about close to the max tolerated for VPLEX which is around 10ms RTT. When “extension.converttonew” is used the amount of IO needed during the switchover is limited, and when each IO takes 10ms you can imagine that has a direct impact on the time it takes to switchover. Of course these enhancements where also tested in scenarios where there wasn’t high latency, or a low number of disks were used, and in those cases the benefits of the enhancements were negligible and the operation overhead of configuring this setting did not weigh up against the benefits.

So to be clear, this setting should only be used in scenarios where high latency and a high number of virtual disks results in a long switchover time during migrations of VMs between hosts in a vMSC/VPLEX configuration. I hope that helps.

EMC VPLEX and Storage DRS / Storage IO Control

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At VMworld various people asked me why VMware did not support the use of Storage DRS and Storage IO Control in a VPLEX Metro environment. This was something new to me and when someone pointed me to a KB article I started digging.

When discussing it with the various teams the following is what we concluded for EMC VPLEX, this is what I drafted up. I have requested the KB to be updated in a more generic fashion (text all the way down below) so that the support statement will apply for all vMSC configurations. Hopefully will be published soon. The EMC specific statement, which I provided to the EMC VPLEX team, will look roughly as follows:

EMC VPLEX supports three different configurations, namely VPLEX Local, VPLEX Metro and VPLEX Geo. This KB article describes the supported configurations for VPLEX Local and VPLEX Metro with regards to Storage DRS (SDRS) and Storage I/O Control (SIOC). VMware supports Storage DRS and Storage IO Control on EMC VPLEX in each of the two configurations with the restrictions described below.

VPLEX Local:
In a VPLEX Local configuration VPLEX volumes are contained within site/location. In this configuration the following restrictions apply:
– Storage IO Control is supported
– Storage DRS is supported
– A Datastore Cluster should only be formed out of similar volumes
– It is recommended to run Storage DRS in “Manual Mode” to control the point in time migrations occur

VPLEX Metro:
In a VPLEX Metro configuration VPLEX volumes are distributed across locations/sites. In this configuration the following restrictions apply:
– Storage IO Control is not supported
– Storage DRS is only supported when “IO Metric” is disabled
– It is recommended to run Storage DRS in “Manual Mode” to control the point in time migrations occur
– Each location/site should have a Datastore Cluster formed only out of dvols (Distributed VPLEX volumes) which are part of the same consistency groups, and only with site bias to that particular location / site!
– Example: Site A will have Datastore Cluster A which contains all dvols with bias to Site A.

The more generic support statement will roughly look like this:

This KB article describes the supported configurations for vSphere Metro Storage Cluster (vMSC) environments with regards to Storage DRS (SDRS) and Storage I/O Control (SIOC). VMware supports Storage DRS and Storage IO Control with the restrictions described below.

In a vMSC configuration volumes are distributed across locations/sites. In both uniform and non-uniform configurations the following restrictions apply:
– Storage IO Control is not supported
– Storage DRS is only supported when “IO Metric” is disabled
– It is recommended to run Storage DRS in “Manual Mode” to control the point in time migrations occur
– Each location/site should have a Datastore Cluster formed only out of stretched datastore and only with site bias to that particular location / site
– Example: Site A will have Datastore Cluster A which contains all stretched datastores with bias to Site A.

Hopefully this will help the folks implementing vMSC today to make the decision around the usage of SDRS. KB team has informed me they are working on the update and as soon as it has been published I will update this article.

** KB Article has been updated: http://kb.vmware.com/kb/2042596 **

Stretched vCloud Director infrastructure

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A while back I wrote about design considerations when designing or building a stretched vCloud Director infrastructure. Since then I have been working on a document in collaboration with Lee Dilworth, and this document should be out soon hopefully. As various people have asked for the document I decided to throw it in to this blog post so that the details are already out there.

** Disclaimer: this article has not been reviewed by the technical marketing team yet, this is a preview of what will possibly be published. When the official document is published I will add a link to this article **

Introduction

VMware vCloud® Director™ 5.1 (vCloud Director) gives enterprise organizations the ability to build secure private clouds that dramatically increase datacenter efficiency and business agility. Coupled with VMware vSphere® (vSphere), vCloud Director delivers cloud computing for existing datacenters by pooling vSphere virtual resources and delivering them to users as catalog-based services. vCloud Director helps you build agile infrastructure-as-a-service (IaaS) cloud environments that greatly accelerate the time-to-market for applications and responsiveness of IT organizations.

Resiliency is a key aspect of any infrastructure but is even more important in “Infrastructure as a Service” (IaaS) solutions. This solution overview was developed to provide additional insight and information in how to architect and implement a vCloud Director based solution on a vSphere Metro Storage Cluster infrastructure.

Architecture Introduction

This architecture consists of two major components. The first component is the geographically separated vSphere infrastructure based on stretched storage solution, here after referred to as the vSphere Metro Storage Cluster (vMSC) infrastructure. The second component is vCloud Director.

Note –  Before we dive in to the details of the solution we would like to call out the fact that vCloud Director is not site aware. If incorrectly configured availability could be negatively impacted in certain failure scenarios.

[Read more…] about Stretched vCloud Director infrastructure