VMware Solutions Discussions

DIsk Align - Need Some Help and Clarification

JAYJAYJAYUK

Hi

I have read various posts on the disk align issues and have 5 questions

First :

Are the following correct

- VMFS3 does NOT need to be aligned

- Windows 2008 VMs do NOT need to be realigned?

Second :

There are three levels of alignment -

1 - Guest OS

2 - VMFS

3 - Netapp

When you run the MBRAlighn tool - does the tool work at layers 2 and 3? I am assuming so ?

Three :

Would the following solution be valid to align disks

- Create a New VMFS using the VS Client

- VMotion off the VMs to the new datastore

Four :

There are many posts about the true benefit of aligning disks. It would appear that only high IO VMs would benefit from Disk Alignment? Is this true?

Five :

How can I confirm which of my VMs have alignment issue and how can I also validate that the Netapp [3270] does indeed have IOP overhead BECAUSE of disk alignment?

Many thanks!

Annabelle

1 REPLY 1

arash

Hello

Here are the answers to your questions :

First:

Q: VMFS3 does NOT need to be aligned :

A: The default offset of VMFS3, when created with the Virtual Infrastructure Client or VMware vSphere Client, is 128 blocks by default, which does not result in misaligned I/O. But keep in mind that here we are talking about the alignment of the VMFS file system on top of NetApp file system WAFL

Q:Windows 2008 VMs do NOT need to be realigned?

A: Windows 2008 VM's use GPT disks instead of MBR. So They do not need to be realigned after being created, but if you are moving a 2k8 VM from VMFS 2 or doing a P2V you probably need to realign your VMs

Second :

There are three levels of alignment -

1 - Guest OS

2 - VMFS

3 - Netapp

Q: When you run the MBRAlighn tool - does the tool work at layers 2 and 3?

A: Actualy it works on the -flat.vmdk file (Guest OS HDD) trying to fix the starting offset for your VM

Three :

Q:Would the following solution be valid to align disks

- Create a New VMFS using the VS Client

- VMotion off the VMs to the new datastore

A: No , thats not a resolution for realigning the disks . Alignment should occure on the starting offset of the guest OS (-flat.vmdk files)

Four :

Q: There are many posts about the true benefit of aligning disks. It would appear that only high IO VMs would benefit from Disk Alignment? Is this true?

A: No , Aligning misaligned VM's will increase the overall performance of the storage system not just the VM's with high I/O

Five :

Q: How can I confirm which of my VMs have alignment issue and how can I also validate that the Netapp [3270] does indeed have IOP overhead BECAUSE of disk alignment?

A: Using NetApp MBRAlign tools you can find out which VMs are misaligned ( MBR tools are no part of the VSC 2.1.1 which you can download from the NOW site for free)

Also here is a link to Best Practices for File System Alignment in Virtual Environments

Announcements
NetApp on Discord Image

We're on Discord, are you?

Live Chat, Watch Parties, and More!

Explore Banner

Meet Explore, NetApp’s digital sales platform

Engage digitally throughout the sales process, from product discovery to configuration, and handle all your post-purchase needs.

NetApp Insights to Action
I2A Banner
Public