Yellow Bricks

by Duncan Epping

Archives for 2009

Repairing your vmdk header files…

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Increasing the size of a disk when a snapshot exists or deleting the wrong folder on your vmfs volume, it’s something that probably has happened to all of us.

This usually means that you will either need to edit the current vmdk header file or even recreate it. Although it’s not a difficult task it’s still error prone cause it’s a manual task, the procedure is outlined in this KB article for those interested.

Eric Forgette(NetApp), also known of mbralign and mbrscan, wrote a script that automates the recreation of a vmdk header file. The script also gives you the option to verify a header and if it’s corrupt fix it. Eric posted his script on the NetApp community forums and it can be found here.

I especially like the “fix” option of which the following is an example output:

[root@x3 root]# vmdkdtool /vmfs/volumes/test/testvm/fixed-template.vmdk

vmdkdtool version 1.0.090402.
Copyright (c) 2009 NetApp, Inc.
All rights reserved.

/vmfs/volumes/test/testvm/fixed-template-flat.vmdk is 12884902400 bytes (12.0000004768372 GB)

size = 25165825 (current 25125)
sectors = 63 (current value 21)
heads = 255 (current value 3)
cylinders = 1566 (current value 106)

NOTE: A backup of the file will be made if you choose yes.
Shall I fix the descriptor file? yes
Creating a backup of /vmfs/volumes/test/testvm/fixed-template.vmdk
Fixed.

Head over to the NetApp communities and pick it up, definitely a must have for your toolkit.

Virtual Geek Week?

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It must have been Virtual Geek week this week! I guess most of you already know Virtual Geek, and if you didn’t you’ve been missing out on the good stuff. Virtual Geek is being maintained by Chad Sakac of EMC and let’s say there’s a reason why his blog is called “Virtual Geek”. Chad posted a series of blog articles which are a must read for anyone interested in storage related to VMware and storage/VMware in general.

It started out with the “VMFS best practices and counter FUD” article where he sets the facts straight and debunks several myths like max amount of vm’s per VMFS volume and the use of extents. Besides countering this FUD there are also some very valuable tips in this article, for instance the advanced setting “Disk.SchedNumReqOutstanding” and the why/where/when.

In his second post this week he revealed that the upcoming release of ESX/vCenter(vSphere) will include the counterpart of the EMC Storage Viewer (vCenter plugin, youtube demo to be found here.). For all Clarion/Celerra customers who are planning on upgrading to vSphere a nice “little” extra!

The third one was the one I have been personally waiting for, the brand new version of the Celerra VSA. If you want to run a virtual “virtual environment” this virtual storage appliance is a must have. Especially if you want to test SRM this VSA will come in handy. Be sure to also download the how to guide that Chad provided in the “HOWTO 401” article.

Number four and five deal about multipathing and MRU behavior. I fully agree that understanding how MRU works is essential if you are using the policy. Post number 5 contains the script that is demoed in post 4. The script load balances the LUNs on the backend of the array(storage processors) and of course makes sure this is reflected on ESX for an optimal performance.

Let’s hope there’s more to come over the next weeks…

Is your PC overweight? Transitioning from fat to thin…

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Being overweight is probably one of the most common problems we face when getting older, and the same actually goes for PC’s. When they age we start to notice that a “bloated” OS just doesn’t cut it anymore. For most companies this usually means that it’s time to replace their desktops for brand new state of the art equipment. Of course with technology like VDI and/or Terminal Services there’s no need to do so. You can easily keep on using your “old” hardware when utilizing any of these two technologies. (Of course I prefer VDI.)

For an optimal experience I usually advise stripping the fat client OS to it’s bare minimum. But this isn’t always necessary as Justin Emerson(VM Junkie) points out in the two articles he recently published on his blog.

The first solution that I recommend to Microsoft Software Assurance customers is Windows Fundamentals for Legacy PCs. This is one of those lesser-known Microsoft OS products, but I think it’s pretty cool. It’s a stripped-down version of Windows XP intended for legacy systems that you can run on very old hardware – down to a 233MHz Pentium. It requires very little disk footprint, and what I like about it is that the default install is very small, as you will see.

From Microsoft’s website, one of the primary use cases of WinFLP is “use existing hardware as Terminal Services clients.” While they’re referring to Terminal Services by name, there’s no reason we can’t use it for Citrix ICA or in our case, VMware View!

Justin wrote two excellent articles of which the above is just a short outtake. These articles explain which steps you would need to take to turn your old overweight windows desktops into thin clients and are a must read for everyone interested in Desktop Virtualization! (Screenshots included)

Making a thin client on fat hardware: part 1
Making a thin client on fat hardware: part 2

Storage VMotion, exploring the next version of ESX/vCenter

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I was exploring the next version of ESX / vCenter again today and did a Storage VMotion via the vSphere client. I decided to take a couple of screenshots to  get you guys acquainted with the new look/layout.

Doing a Storage VMotion via the GUI is nothing spectacular cause we all have used the 3rd party plugins. But changing the disk from thick to thin is. With vSphere it will be possible to migrate to thin provisioned disks, which can and will save disk space and might me desirable for servers that have low disk utilization and disk changes. [Read more…] about Storage VMotion, exploring the next version of ESX/vCenter

Pre-installing the vCenter agent?!

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You might wonder why you would want to pre-install the vCenter agent on an ESX box? Well if you have several remote offices which need to be connected to a central vCenter Server it will take a while before these agents are pushed and installed. Especially if the connection between these sites isn’t as fast as most of us are used to at home. (I’m talking 128KB here for instance…) One of my colleagues, as mentioned in a previous article, is doing a major roll out of ESX. With their current bandwidth adding an ESX server to the central vCenter Server took over 20 minutes. With the vCenter agent pre-installed this was cut down to only 2 minutes. That will save you a lot of time when you need to do over 200 hosts…

  • On the vCenter Server, look for the following files in C:\Program Files\VMware\Infrastructure\VirtualCenter Server\upgrade 
    vpx-upgrade-esx-7-linux-104215
    vpx-upgrade-esx-7-linux-104215.sig
  • copy the files to the ESX host and run the following commands: 
    sh vpx-upgrade-esx-7-linux-104215
    service mgmt-vmware restart
  • wait 5 min…