vSphere-land.com is running it’s annual Top 25 virtualization blog survey again and I’m really interested to see who are picked this year. Like previous year, some great bloggers disappear while other new great ones emerge. One guy I want to mention by name is Chris Colotti, his blog is a great source of information about vCloud Director. If you haven’t visited his blog yet, go do that right away!.
Last year I’ve been pretty busy writing, shaping, designing, wrestling with publishers in order to get our (@DuncanYB) book “vSphere 5 Clustering technical deepdive out to the public. This meant it cut down on research time, which resulted in a smaller number of blogs being released than previous years. So after seeing other people’s blog about their top 10, I was curious to see what I’ve done last year. The articles that are listed are the ones I’m proud of, spending a lot of time on researching them, but most of all, enjoyed the most writing them.
Storage DRS initial placement and datastore cluster defragmentation
Impact of Load Balancing on datastore cluster configuration
Partially Connected datastore clusters
Mem minfreepct sliding scale function
Upgrading vmfs datastores and Storage DRS
Multi NIC vMotion support in vSphere 5.0
Contention on lightly Utilized Hosts
Restart vCenter results in DRS load balancing
IP-HASH versus Load Based Teaming
Setting correct percentage of cluster resources reserved
AMD Magny Cours and ESX
Please take 5 minutes of your time and vote for your favorite blogger. I hope they will announce the winner like they did last year. 90 minutes of nerve wrecking but oh-so-enjoyable videoshow!
Cast your vote now!

We lowered the price of the vSphere 4.1 HA and DRS technical Deepdive book permanently. As of this week you can obtain one of the coolest books in the virtualization section at Amazon for only $19.95. 30 5-star reviews couldn’t be wrong. Here is just a random selection of two of those 5-star reviews:

B. Riley: The term “deepdive” is regularly abused in the technology world these days. There’s nothing more disheartening than walking into a one hour session at a conference entitled deepdive, and finding out that it’s neither deep, nor a dive. It ends up being more like sitting in a couple inches of warm water in a plastic kiddie pool.
When these guys say deepdive, they mean it. This book is packed with helpful information from the first, to the last page. Somehow, they even manage to read minds. They know what you’re thinking as a VMware administrator, and they’ll tell you the why, and the best practice.
Lots of books have good overviews of HA and DRS, but none goes as deep as this. It’s very well-written, and highly recommended for anyone who is running, or thinking about running an HA/DRS environment.
This book is, as Jeremy Clarkson would say, “absolutely brilliant”!

Chris Dearden: Ever had a series of discombobulated thoughts and ideas that have suddenly clicked into place & the plans come into focus? That’s exactly what happened when I read Frank & Duncan’s book. Even though I have a fair few years experience with Enterprise virtualisation , my knowledge of what’s deeply under the covers of the availability options of vSphere was made up of blog posts I’d read , anecdotes from colleagues and a few slides from trainers. It was enough to get me by, but there was always that nagging feeling that I wasn’t fully in control of what was happening.
After reading the book ( in a morning – for a tech book it’s one that you can work though in a short amount of time and still get value from ) I had a real epiphany / light bulb moment / matrix moment / and all of those concepts and ideas suddenly had a deeper meaning and the big picture was visible. For anyone who thinks they know about HA / DRS : read this and *really* know about it.

Get your copy now at: vSphere 4.1 HA and DRS technical deepdive Amazon page

Among many new cool features introduced by vSphere 5 is the new VMFS file system for block storage. Although vSphere 5 can use VMFS-3, VMFS-5 is the native VMFS level of vSphere 5 and it is recommended to migrate to the new VMFS level as soon as possible. Jason Boche wrote about the difference between VMFS-3 and VMFS-5.
vSphere 5 offers a pain free upgrade path from VMFS-3 to VMFS-5. The upgrade is an online and non-disruptive operation which allows the resident virtual machines to continue to run on the datastore. But upgraded VMFS datastores may have impact on SDRS operations, specifically virtual machine migrations.
When upgrading a VMFS datastore from VMFS-3 to VMFS-5, the current VMFS-3 block size will be maintained and this block size may be larger than the VMFS-5 block size as VMFS-5 uses unified 1MB block size. For more information about the difference between native VMFS-5 datatstores and upgraded VMFS-5 datastore please read:
Cormac’s article about the new storage features
Although the upgraded VMFS file system leaves the block size unmodified, it removes the maximum file size related to a specific block size, so why exactly would you care about having a non-unified block size in your SDRS datastore cluster?
In essence, mixing different block sizes in a datastore cluster may lead to a loss in efficiency and an increase in the lead time of a storage vMotion process. As you may remember, Duncan wrote an excellent post about the impact of different block sizes and the selection of datamovers.
To make an excerpt, vSphere 5 offers three datamovers:
• fsdm
• fs3dm
• fs3dm – hardware offload
The following diagram depicts the datamover placement in the stack. Basically, the longer path the IO has to travel to be handled by a datamover, the slower the process.

In the most optimal scenario, you want to leverage the VAAI capabilities of your storage array. vSphere 5 is able to leverage the capabilities of the array allowing hardware offload of the IO copy. Most IOs will remain within the storage controller and do not travel up the fabric to the ESXi host. But unfortunately not every array is VAAI capable. If the attached array is not VAAI capable or enabled, vSphere will leverage the FS3DM datamover. FS3DM was introduced in vSphere 4.1 and contained some substantial optimizations so that data does not travel through all stacks. However if a different block size is used, ESXi reverts to FSDM, commonly known as the legacy datamover. To illustrate the difference in Storage vMotion lead time, read the following article (once again) by Duncan: Storage vMotion performance difference. This article contains the result of a test in which a virtual machine was migrated between two different types of disks configured with deviating block sizes and at a different stage a similar block size. To emphasize; the results illustrates the lead time of the FS3DM datamover and the FSDM datamover. The results below are copied from the Yellow-Bricks.com article:

From(MB)	To	Duration in Minutes
FC datastore 1MB blocksize	FATA datastore 4MB blocksize	08:01
FATA datastore 4MB blocksize	FC datastore 1MB blocksize	12:49
FC datastore 4MB blocksize	FATA datastore 4MB blocksize	02:36
FATA datastore 4MB blocksize	FC datastore 4MB blocksize	02:24

As the results in the table show, using a different blocksize lead to an increase in Storage vMotion lead time. Using different block sizes in your SDRS datastore cluster will decrease the efficiency of Storage DRS. Therefore it’s recommended designing for performance and efficiency when planning to migrate to a storage DRS cluster. Plan ahead and invest some time the migration path.
If the VMFS-3 datastore is formatted with a larger blocksize than 1 MB, it may be better to empty the VMFS datastore and reformat the LUN with a fresh coat of VMFS-5 file system. The effort and time put into the migration will have a positive effect on the performance of the daily operations of Storage DRS.

It looks like Amazon is getting its game together. As of now the Black and White paperback edition is available at Amazon.com. Get it here:
VMware vSphere Clustering Technical Deepdive
We are still waiting for the Full color edition to become available, but hey it’s a start 🙂

The entire week Amazon hasn’t been able to index both vSphere 5 Clustering technical deepdive editions properly.
We are working with Createspace to fix these problems. In the meantime, both full color and black and white editions can be ordered at Createspace:
Black and White: https://www.createspace.com/3641804 $29.95
Full Color: https://www.createspace.com/3586911 $49.95
An update follows as soon as Amazon list the paperbacks.