Yellow Bricks

by Duncan Epping

Archives for 2009

Performance Week?!

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It seems to be performance week this week at VMware. It started out with Eric Horschman’s reply to Virtualization Review’s hypervisor performance comparisson. What amazed me the most, besides the results, is the fact that Keith Ward writes that the methodology was discussed with VMware and VMware agreed that it was fair. Reading Eric’s response this certainly isn’t the case. What stood out in Eric’s reply and what also surprised me when reading the original article by Rick Vanover is the following:

“The fact that ESX is completing so many more CPU, memory, and disk operations than Hyper-V obviously means that cycles were being used on those components as opposed to SQL Server.”

Now I’m not going to analyse Rick’s test or Eric’s response, there’s no need to do so. Others are far more capable of doing that, like for instance Chris Wolf. Chris has a valid point, we really need SPECvirt, and we need it fast to get wrid of these endless discussions. For those not familiar with the SPECvirt initiative you can dive into it here. SPECs motto describes best what it’s about:”The key realization was that an ounce of honest data was worth more than a pound of marketing hype”. [Read more…] about Performance Week?!

Train Signal coupon, 20% off!

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I just received an email from Train Signal. They can offer a 20% reduction on all CBTs! Head over to Train Signal, support yellow-bricks and learn how to fully utilize VMware products at the same time! Click here for more info!

Offer: 20% Off
Code: Irish
Duration: 03/12/09-03/18/09

Enjoy!

Disabling the VMFS-2 module! Exploring the next generation of ESX

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When I started out with ESX 3.0.x the first thing I wanted to do was disable the VMFS-2 driver. There’s no need for it when you’re not accessing VMFS-2 volumes and removing it can lead to performance gains or at least a faster rescan of your storage. Removing it, according to to this section of the VMware website, was supposed to be really easy:

vmkload_mod -u vmfs2

Unfortunately, this just unloads the module and every time the server gets rebooted the module is loaded again. Same goes for the esxcfg-module command, it unloaded it but after a reboot the module was loaded again. You could add the command to /etc/rc.local of course. This would unload the module every time the server booted. I’m not a big fan of manually changing files like this, and luckily as of the next generation of ESX(vSphere) this doesn’t seem to be necessary anymore:

esxcfg-module -d
-d|--disable - Disable a given module,
indicating it should not be loaded on boot.

The funny thing is when I run the “esxcfg-module -l” command it still lists the module as loaded. If I run the “esxcfg-module -q”, which only queries the enabled modules, it’s not listed. After a closer investigation I noticed that the following line changed in “/etc/vmware/esx.conf”:

/vmkernel/module/vmfs2/enabled = "false"

I did a cross-check, it’s most definitely not loaded. Cool, remember this one “esxcfg-module -d”. It will come in handy some day.

VMFS recognized as a snapshot what to do? Exploring the next version of ESX…

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Your VMFS has been recognized as a snapshot, what are you going to do? Hopefully most of you have read my previous post on this topic by now. If you didn’t, be very ashamed and start reading my EnableResignature post before you continue.

I was just playing with a VMworld Europe lab manual, which was about the next version of ESX/vCenter(Part of vSphere). I noticed the following new command on the command-line: esxcfg-volume. I did a help and the following showed up:

-l | --list
-m | --mount <vmfs uuid|label>
-u | -- umount <vmfs uuid|label>
-r | -- resignature <vmfs uuid|label>
-M | --persistent-mount <vmfs uuid|label>

As you can imagine this command will come in handy when a VMFS/LUN is being recognized as a clone or snapshot! With version 3.5 you needed to change an advanced setting. This setting wasn’t specifically for just one LUN, but for all of them, which is a risk. With the next version of ESX you could do the following if a volume has been detected as a snapshot and you want to resignature it:

  1. esxcfg-volume -l
  2. esxcfg-volume -r 49ba276a-c9e135b6-26f8-000c29123ede

Or if the current cloned volume isn’t connected you could also just mount it:

  1. esxcfg-volume -l
  2. esxcfg-volume -m 49ba276a-c9e135b6-26f8-000c29123ede

And if you are absolutely sure the cloned volume will not return you could mount it persistantly, which is the equivallent of “EnableResignature=0, DisallowSnapshotLUN=0”:

  1. esxcfg-volume -l
  2. esxcfg-volume -M 49ba276a-c9e135b6-26f8-000c29123ede

Don’t you just love this new exciting command-line magic! There’s more to come over the next days/weeks.

btw: there’s also a way of doing this from the GUI… Just add a new LUN, select the LUN that you want to mount, depending on what needs to be done pick “Assign a new signature” or “Keep Existing Signature”. But where’s the fun in that?

ThinApp Deployment Guide

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I just noticed this excellent guide on deploying ThinApp. I would suggest that anyone that wants to start using ThinApp looks into this guide, I guess it could be considered as a “mini-course” on howto ThinApp an application:

This document provides guidance for customers seeking to package and deploy applications efficiently with VMware ThinApp. It addresses most relevant deployment considerations but does not provide comprehensive detail. Please see the VMware ThinApp User’s Manual for the specifics of implementation and further explanation.