IOPs, Bandwidth, Throughput…

Storage Contention

I was given a chart from a vendor that shows raw throughput of a disk array they suggested I purchase. This chart was a comparison between one array versus a list of others in terms of throughput.  In an attempt to objectify this storage contention idea that keeps getting thrown in my face, I looked up the definitions of IOPS, throughput, and Bandwidth and their relationships in a storage environment.  Here’s what I learned:

  • IOPS = IO’s Per Second which is 1 / (average latency in ms + average seek time in ms) also based on block size
  • Throughput = Amount of data the network can handle (3Gb, 6Gb, 12Gb SAS)
  • Bandwidth = Network speed of the storage device (7.2k, 10k, 15k RPM drives)

Being somewhat of a gear head, I see these terms correlate closely to automotive concepts of horsepower, torque, and vehicle function.  We Americans are known to purchase horsepower off-the-lot; however, we drive torque when choosing our vehicles. Likewise, many computer guys purchase throughput – 10k vs. 15k SAS drives when our applications actually “drive” IOPS.  It is rare that a user’s speed perception and end-user experience is based solely on throughput. A high-horsepower vehicle may under-perform when compared to a lower-horsepower yet higher low-end torque vehicle at the green light. So, why is it that sales people and application vendors focus solely on drive RPM speed bandwidth and storage network throughput?

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Upgrading to ESXi 4.1?

What’s New in VMware vSphere 4.1 for Small and Midsize Businesses

I just watched this video from VMWare regarding virtualization, VMotion, and what’s important for small/medium businesses (SMB). There were a couple of interesting questions that were asked in the web conference:

For us small people will you ever change the cost structure for VCenter? (ie Two license options; 6 proc <Foundation> or Unlimited). For a small company we have 4 two proc servers and cannot justify they cost for an unlimited VCenter for adding just one more server.

Agreed: the vCenter license cost seems to be out of line with the rest of the licensing especially for smaller implementations.
We’re investigating this – appreciate the feedback.

Is it necessary to have a SAN to take advantage of all the features of vSphere?
It’s necessary to have shared storage – this could be NAS, SAN, etc.

Is this a trial version that has a trial period, such that it’s better to go to essentials plus kit?
No this is not a trial version. This a free version of vSphere with perpetual license. vSphere Hypervisor cannot be centrally managed from vCenter. Only locally via vSphere Client.

For storage vmotion, is it possible to vmotion a vm across data centers in 4.1?
It is possible, but it is not very easy. You need the right storage architecture.

One thing that I’m finding consistent as time passes and as users become more familiar with VMWare: they are asking more targeted questions regarding their storage infrastructure.  By reading these questions, I am assuming that administrators are demanding more and expecting to pay a lot less for their storage as well.  Just wait…  Something’s around the corner when it comes to addressing storage requirements and I don’t think it’s going to be an expensive piece of hardware.

Desktop Virtualization

I had a phone call with a friend of mine at another cooperative regarding virtual desktops.  He read a magazine article about the drug that some are now using to deploy their desktops. He asked if I had experienced the hallucinogenic and euphoric effects that he read it would provide.  I told him I wasn’t interested in it – at all.  When he bluntly asked me “why not?”, I felt an obligation to answer him:

Desktop virtualization makes no sense to deploy in my environment.  In the case of server virtualization, several computers in the data center were using more hardware than their applications demanded.  CPU utilization was low, processor core time was limited to the number of threads an application is programmed to use, there was duplication of duplication, and the user experience requirement was practically non-existent. Virtualization makes perfect sense to me in a server environment.
Looking at user desktops, I see virtualization as a solution in need of a problem in my cooperative. Actually, I see it as more of a bane than a cure.  Why, I can purchase a dual-core 2.8GHz processor desktop with 2GB of RAM, dual-headed video, sound, and a Windows OS pre-installed for the same amount of money as a dumb terminal device.  The dumb terminal’s capabilities are far less than what I get for the desktop.  The flexibility of the desktop meets and exceeds the requirement for just about any user and for the same price; I don’t feel like I’m painting myself in a corner like I would with a terminal.  With that desktop PC, I have processing power that is designed to meet the dynamic needs of each user which are very different than the relative fixed demands and requirements of a server.  Also, just because virtualization works well in the datacenter does not mean it will work equally well on the desktop.  These are very different worlds.

Given the decision to buy a house or rent an efficiency apartment, I found that the house might cost just as much as the apartment.  I later found that the purchased house will absolutely cost less than the apartment – both short and long term.  Given these facts, what choice in housing do you think I should make?

There’s no amount of rationalizing that one can apply to make an apartment sound appealing to me given these facts.  Granted, one does not have to maintain an apartment as much as a house just like desktop virtualization vs a desktop PC – but at what cost to the users and the business?  In the end, you’re paying a lot more for a lot less. This doesn’t make a lot of sense to me.

I’m not saying that it isn’t a solution for some.  I can just about guarantee you that it’s not a solution for me – yet…

TechAdvantage 2011 – Storage Virtualization


There were several off-line comments and questions that I have been getting from cooperatives regarding the necessity for virtualization storage requirements. I mentioned in the presentation that we did not deploy with a storage area network (SAN).  This seems to confuse many as to why or how we were able to do that.  The purpose of this post is to address the storage options that you can have in a virtual server environment and give you the pros and cons of setting them up.

Why Storage is Important

The importance of storage in a VMware environment is paramount. I would rate the necessity for storage to be higher than the amount of processing speed one rates the CPU’s on the host.  Why? Here is the reality: Read the rest of this entry »

TechAdvantage 2011 – Installing ESXi 4.x


There are several howto’s out there on how to install ESXi.  There are even ones that are specific to your particular hardware if you search enough.  Instead of reinventing the wheel here, I’m going to share the checklist that I put together during our disaster recover exercise.  Following my internal documentation, I will include some links and videos that I thought will be helpful.

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TechAdvantage 2011 – Virtualization Questions

Questions asked before and after the presentation are posted here.

There’s been a big push in the Midwest for Google Gmail to take over in-house hosting our e-mail.  My Redhat is 7 years old, handles all our e-mail and should be replaced.  You mentioned Postini: should I outsource my e-mail entirely?

In my opinion, the fact alone that your server is 7 years old is not a compelling reason to move to Gmail.  There are usually 3 reasons people choose to upgrade: technology, security, and functionality mandate.  All of these are really driven by risk and cost.  Cost does not always have to equate to dollars but it is good to do so if you have to explain it to someone other than yourself.  The way I rationalize with it is that if the cost of holding what you have exceeds the cost of the technology upgrade, then you need to upgrade.

In your case, hardware “getting old” would fall into a technology mandate.  The hardware needs to be replaced because it is seven years old.  You can purchase a less-problematic and brand new box for relatively less cost than is required to maintain the current one.  Because your e-mail is doing everything that you want it to, this would not fall into a functionality mandated upgrade.  E-mail is really a simple and common service for an IT department.

Again, this is only my opinion, but moving to Gmail without defining a business need would be like throwing the baby out with the 7-year-old bathwater.  This is not a good practice in most cultures.  With virtualization, the bathwater can always be fresh.  No reconfiguration necessary.  All stays the same and essentially eliminates the technology mandated reasons for upgrading – such as a dated server.

Didn’t you guys do it backwards?  Should you have purchased a SAN first? Read the rest of this entry »

TechAdvantage 2011 – Virtualization

I just uploaded all of the video to YouTube today.  Here are the videos if you care to view them:

Part I

Part II

Part III

Stay tuned…

I am finishing the post of how-to virtualize for free.  This will be a step-by-step guide on how we accomplished this task.  Also, I will be posting some more information based on some of the questions that Ben and I were asked before and after this presentation.

(Edit: trouble with transcoding video.  A replacement video is being uploaded)

Understanding Microsoft Licensing – hitchhiker’s guide

“As long as the installation wizard takes the Product Activation Key, we’re good!”
“Peel off the COA and keep it handy before you throw that old computer away.”
-Administrator’s famous last words

“Just get SA. It’s so easy… and cheap.”
-CDW representative

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