Yellow Bricks

by Duncan Epping

vmworld

Call for speakers for Lightning and NotSupported talks at VMworld Barcelona

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At VMworld San Francisco the vBrownBag crew and Randy Keener held a series of excellent talks at the community lounge. Randy was responsible for the “NotSupported” talks and the vBrownBag crew ran the “lightning” talks. Both type of sessions were typically around 10-15 minutes tops and technical…

The Brown Bag crew is organizing these talks again for Barcelona and they are looking for people to present. Did you submit a session for VMworld but got rejected? Have you always wanted to do a lightning talk? Got something cool but totally unsupported that you want to share?

S I G N – U P – T O D A Y !

I will be there for sure, this is Europe… lets show them how it is done. 10 minutes, who can’t spare 10 minutes… Go for it I say,

Nice advanced ESXTOP tip from #VMworld session INF-VSP1423

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I was watching INF-VSP1423 – esxtop for Advanced Users today by Krishna Raj Raja. This is a VMworld 2012 San Francisco session, if you attended SF but did not attend this session look it up and watch it… If you are going to VMworld Barcelona, schedule it. It is an excellent session, deep technical with some great insights presented by a very smart VMware engineer. There was a tip in there which I found very useful.

Krishna showed an example where he noticed a lot of I/O being generated on a particular LUN. How do you figure out who / what is causing this? Well it is not as difficult as you think it would be…

  • Open up esxtop (more details on my esxtop page)
  • Go to the “Device” view (U)
  • Find the device which is causing a lot of I/O
  • Press “e” and enter the “Device ID” in my case that is an NAA identifier so “copy+paste” is easiest here
  • Now look up the World ID under the “path/world/partition” column
  • Go back to CPU and sort on %USED (press “U”)
  • Expand (press “e”) the world that is consuming a lot of CPU, as CPU is needed to drive I/O

This should enable you to figure out which world is driving the high amount of I/Os. Now you can kill it, contact the user / admin causing it… nice right.

There are some more nuggets in this session around PSTATE (power state), co-sharing, Host Caching (llswp) and much more… I am not going to reveal those as you should be attending this session or at a minimum watch it online.

VMworld session report: INF-STO2223 – Tech Preview vSphere Integration with Existing Storage

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A couple of weeks ago I posted an article about Virtual Volumes aka vVOLs. This week at VMworld Thomas (Tom) Phelan and Vijay Ramachandran delivered a talk which again addressed this topic but they added Virtual Flash to the mix. The session was “INF-STO2223”.

For those attending Barcelona, sign up for it! It is currently scheduled once on Wednesday at 14:00.

The session started out with a clear disclaimer, this was a technology preview and there is no guarantee whatsoever that this piece of technology will ever be released.

Tom Phelan covered Virtual Flash and Vijay covered Virtual Volumes but as Virtual Volumes was extensively covered in my other blog post I would like to refer back to that blog post for more details on that topic. This blog post will discuss the “Virtual Flash” portion of the presentation, virtual flash or vFlash in short is often also called “SSD caching”.

The whole goal of the Virtual Flash project is to allow vSphere to manage SSD as a cluster resource, just like CPU and memory today. Sounds familiar right for those who read the blog post about vCloud Distributed Storage?! The result of this project should be a framework which allows partners to insert their caching solution and utilize SSD resources more effectively without some of the current limitations.

Virtual Flash may be VM-transparent but also VM-aware. Meaning that it should for instance be possible to allocate resources per virtual machine or virtual disk. Some controls that should be included are reservations, shares and limits. On top of that, it should fully work with  vMotion and integrate with DRS.

Two concepts were explained:

  1. VM transparent caching
  2. VM-aware caching

VM transparent caching uses a hypervisor kernel caching module which sits directly in the virtual disk’s data path. It can be used in two modes, write thru cache (read only) and write back cache (read and write). On top of that it will provide the ability to migrate cache content during a vMotion or discard the cache.

VM-aware caching is a type of caching where the Virtual Flash resource is presented directly to the virtual machine as a device. This allows the virtual machine to control the caching algorithm. The cache will in this case automatically “follow” the virtual machine during migration. It should be pointed out that if the VM is powered off the cache is flushed.

For those managing virtual environments, architecting them or providing health check services… think about the most commonly faced problem, yes that typically is storage performance related. Just imagine for a second having a caching solution at your disposal which could solve most of these problems…. Indeed that would be awesome. Hopefully we will hear more soon!

INF-BCO2807 – vSphere HA and Datastore Access Outages tech preview

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All of you know by now that I have a love for availability related topics… Hence the reasons I needed to write something about INF-BCO2807. The session titled “vSphere HA and Datastore Access Outages – Current- Capabilities Deep-Dive and Tech Preview”, presented by Keith Farkas and Smriti Desai, discussed possible future HA enhancements that will solve component failures. Those of you who read my whitepaper on stretched clusters can immediately see why this would be a nice enhancement!

Once again a big fat disclaimer, VMware gives absolutely no guarantees when or even if this will be released.

This session was all about inaccessible data stores. During our talk Lee Dilworth and I explained the difference between a Permanent Device Loss (PDL) and an All Paths Down (APD) condition. In short, PDL is a “scsi sense code” issued by the storage system (or an iSCSI “login reject” for that matter). This scsi sense code allows vSphere (both the kernel and HA) to respond and act upon it. In the case of an APD vSphere cannot respond… the LUN is gone on that host and we don’t know why, so what do we do? Well with 5.1 and prior we do nothing. This results in zombied virtual machines, and that is not the state you want your virtual machines to be in right?

So how is VMware planning to solve this? It is planning to enhance HA with what was referred to as “Component Protection”. Component Protection allows responses per virtual machine when an APD or PDL has been detected. This is not based on guest I/Os failing, but on the vSphere platform declaring that the device is in a PDL or APD condition.

When an APD scenario is detected HA will be smart enough to understand which hosts can restart virtual machines, as in some cases multiple hosts might be impacted. Of course it will also only kill your virtual machine and restart it when it knows capacity is available for it.

I don’t know about you, but I would rather see this implemented today than tomorrow!? APD is not common, but also not rare… and when disaster strikes, it strikes hard!

I don’t think this session is scheduled for VMworld Europe, so make sure to watch the recording as soon as it is available as it is well worth your time. Keith and Smriti gave an excellent deepdive on the current vSphere HA and a nice look in to the future!

MyVMworld report

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VMworld has always been the craziest week of the year for me personally and 2012 was no exception. Being closely involved with the vCloud Suite launch I had an idea around what to expect, but I would not have expected the week to be this intense.

It is going to take me a couple of weeks to properly recover, but it was worth it. This report gives an idea of all that was going on in “my world” at VMworld 2012 in San Francisco.

Day 0

My VMworld started on Sunday at TAM day with the Birds of a Feather (BoF) lunch. These lunches are particularly interesting as you get to talk to customers in an informal setting. I was part of the BC/DR table and most of the discussions were around stretched VLANs, application discovery and re-ip’ing. I guess common operational and architectural problems people face…

[Read more…] about MyVMworld report