prutter
Enthusiast
Enthusiast

Alligning VM's

i was told that i should allign my vm's and can'te really say i know what they mean. Can anyone shed a little tight on this subject adn maybe point me in the right direction? Any help is appreciated.

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10 Replies
Troy_Clavell
Immortal
Immortal

maybe this document will be helpful

....or the most current

http://www.vmware.com/pdf/Perf_Best_Practices_vSphere4.0.pdf

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tekka
Enthusiast
Enthusiast

There were some threads and in particular this one:

http://communities.vmware.com/message/1371929

where I posted yesterday some comments about doubts, in particular for multi-partitions configured disks....

Probably as these question often arise again, it could be a hint to go deeper in examples and cases and update the docs?

Thanks,

Gianluca

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msemon1
Expert
Expert

I ran fdisk -lu. Most of my partitions are aligned at 128 including my boot partition, however, I have some others which are aligned at 63. Do I need to worry about partitions other than boot that are not aligned?

Mike

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prutter
Enthusiast
Enthusiast

How do i know if i need to allign the VMFS partitions? Looks like all the partitions start at 128 and based on what i'm reading that is alligned.

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msemon1
Expert
Expert

If all of your partitions are aligned on 128 then I think you are good. Most of my partitions are aligned on 128, a couple are 63. The 50 dollar question is do all of them need aligned on 128 or is the most important the boot partition which must be 128.

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tekka
Enthusiast
Enthusiast

The /boot partition is the least important of all IMHO, as it gets pratically no I/O on it, apart from when you do a kernel install and an initrd generation.

In fact you could also unmount /boot in a running system without problems...

Inside the white paper there are some points that are kept superficial.... system disk vs data disk .... if you have an application server you don't get another disk only to accomplish this division between data and system....

They don't take in mind what is system management and administration...

You start from the bottom and you have vmfs that is aligned, virtual disk that is aligned (both automagically if done inside vcenter server)

btw, as far as I know you should not do operations such as mv or cp for virtual disks, considered as files of the vmfs file system: you are not garanteed to have an aligned resulting vmdisk file this way....

And arriving at the top side, I think it makes sense to align all the partitions. Infact I setup a kickstart file (but working with templates this part could be less important actually when you have done once) so that I could align all the partitions, moving the disk partitioning to the %pre section .

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prutter
Enthusiast
Enthusiast

So now can i tell if my VMDK's need alligned? Is there a way in the OS (Windows) to tell if those need alligned? This is way out of my comfort zone if you couldn't tell. Thanks again.

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alin1
Contributor
Contributor

Here are some attached documents from NetApp regarding block alignment.

We're using Vizioncore's vOptimizer to align our VMs.

Message was edited by: alin1

Sorry, I was not able to attach the other documents because they are over the max size each.

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dconvery
Champion
Champion

There's really no need to align your boot/system partition, only the data partitions. Steve CHambers and I created a Proven Practice Guide on the VI:OPS forums. It explains the "whys" and "hows".

http://viops.vmware.com/home/docs/DOC-1407

Dave Convery, VCDX

VMware vExpert 2009

http://www.dailyhypervisor.com

Careful. We don't want to learn from this.

Bill Watterson, "Calvin and Hobbes"

Dave Convery, VCDX-DCV #20 ** http://www.tech-tap.com ** http://twitter.com/dconvery ** "Careful. We don't want to learn from this." -Bill Watterson, "Calvin and Hobbes"
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