Wednesday, June 30, 2010

VMWare store I/O control (SIOC)

Recently I’ve been seen several posts about storage control and I decided to understand where it’s coming from:

As far as I could understand it started back in 2009 during VMworld, one of the articles was about it. Click here to see

Then on June 2010, VMWARE released a video showing how it should works. (see it bellow)

How it works:
- It’s enable per Datastore
- You should set shares per VMs
- You can define IOPs limits per VMs

So, the host monitors it’s latency with the datastore when it reaches it’s limit all the VMs accessing it are prioritized according with it’s shares, just like CPU/Memory constrains, then each VM will have it’s share to access the storage, avoiding one VM to monopolizes the storage and kill the performance for every other VM.


Well, let’s be honest, it’s a very cool thing… I don’t know you guys, but by internal security policies we must run an antivirus scan once a week, it’s killing my VM’s.
A Bunch of VMs scanning a shared storage at the same time makes a lot of latency on the I/O and drops the performance on the storage aggressively. We tried to split the scan schedule across other days and times, which helped us a little bit, but did not solve the whole problem.

VMware is saying it should be available on VSphere 4.1 release. Let’s see…

Thursday, June 17, 2010

Right Size your VM

If you are new with virtualization, your clients does not understand that requisites for a virtual server differs from physical servers or even if you don’t have a baseline yet to measure your needs, there’s a website that you can use to check what the others are doing with their own VMs.

CompareMyVM allows you ,for free, on learning how to right size your VM, compare VMs by applications and other categories.

It could be a good start.
But my advice is always monitor and measure up the performance of your VMs, if you can overestimate your VM’s requisites and never revisit it you will probably be wasting a lot of resources.
Try to start small, monitor and increase as required…
It’s always easier to increase capacity then decreasing it.

Friday, June 11, 2010

Platespin issue preventing P2V

There could be situation when you want to convert a physical server with PlateSpin and it does not work.
If you check the logs you realize something that drives you to think that the problem could be with firewall or an IP source not answering…

Well it occurs if you have a NIC not configured on your source server.
Just disable any NIC that’s not in use and start the virtualization again.

It should works fine this time ; )

Friday, June 4, 2010

VMware disk alignment

If you have never heard about it don’t be shy, raise your hand…. I did not know about it like one year ago either.

If you have a guest suffering from performance or even your entirely environment and you don’t know where to look at anymore ….

Your problem might be misalignment volumes/disk.

An unaligned partition results in a track crossing and an additional I/O, incurring a penalty on latency and throughput. The additional I/O (especially if small) can impact system resources significantly on some host types. An aligned partitions ensures that the single I/O is serviced by a single device, eliminating the additional I/O and resulting in overall performance improvement.

Some Tips are:
- Always use Virtual Center to create configure your storage (don’t know why someone would do different, but disk alignment is possible on datastore and VMDK)
- Newer OS as Windows 2008 don’t have this issue
- Check your storage vendor for the correct disk alignment

VMWARE has created a good topic about it…here!!

If you are like me and want a visual clarification click here and check this good blog about it.

example of a disk aligned:

Who am I

My photo
I’m an IT specialist with over 15 years of experience, working from IT infrastructure to management products, troubleshooting and project management skills from medium to large environments. Nowadays I'm working for VMware as a Consulting Architect, helping customers to embrace the Cloud Era and make them successfully on their journey. Despite the fact I'm a VMware employee these postings reflect my own opinion and do not represents VMware's position, strategies or opinions. Reach me at @dumeirell

Most Viewed Posts

Blog Archive