Data Store Size Limits in VMware ESX and ESXi

Well, you took the leap and are now virtualized.  You’re now doing more than ever, and data size is growing rapidly.  Time to add a new virtual hard drive to your machine, but wait…  I said 500 GB, why is it only 256 GB.  Well, you hit a limitation of the data store in VMware under your current default configuration.  Check to see what your data store block size is.  here’s where to find it:

Highlighted you will see the datastore block size.

Highlighted you will see the data store block size.

When data stores are created, their default block size is 1 MB, which gives you a maximum virtual hard drive size maximum of 256 GB.  So how do you get larger VHD’s?

Hopefully you are reading this and have a brand new ESX/ESXi setup, in which case you can just delete the data store and recreate it, choosing a different block size.  If you already have machines running on the data store, you have a project ahead of you, because deleting the data store will format all data on that drive, and you will have to start from scratch, or be creative before you make the change (there are some ideas of how to work around this below).

If you have the disk space to cover 2TB, then I would go with the maximum of 8MB block size to give you a maximum virtual HDD size of 2TB.  There is no noticeable I/O performance difference by using maximum size, so use the largest size to mazimize your storage.  Here is a quick reference of what block size you can choose and what the maximum VHD that will give you:

Block Size     Max VHD size

1MB                256GB
2MB               512GB
4MB               1TB
8MB               2TB

Already have servers running?  How do you fix it?

If you already have the data store in use, and can afford some downtime for a maintenance window, here is a workaround you could do, asuming you have more than one ESX(i) server at your disposal.  You can power the VM down and use the free VMware vCenter Converter ( to move the virtual machine from one ESX(i) server to another.  Figure on about 1 minute per gig of hard drive size when moving it, with a GB network.  Once the VM is moved to its new location, power it an and make sure all is working well before you delete from disk the VM on the original ESX(i) server.  Once all the VMs are moved off the ESX server, you can go ahead and remove the data store and create a new one using the new block size.

If you hapen to have your VMs in a cluster with vMotion, this task is even easier, as you can change the location of the datastore through the migrate option.  If you dont have any other ESX servers, you could probably do it to VMware Servers, but at that point, you would probably be better just adding multiple drives to the VMs, it would be a lot less work.

Here is a nice reference guide from VMware with this and other importand configuration information:

Got Backup? – Bad hard drive sounds and what they mean

We have been seen our fair share of bad hard drives lately.  We are passionate about setting customers up with two forms of automatic backup (on site and off site) because hard drives do fail.  Lets face it, backup is so easy and cheap these days there is no real excuse for lost information.   Don’t be stuck without backup!

Ok, so your hard drive fails.  How do you diagnose the failure?  Is it the click of death?  Are there bad heads, bad clusters, a stuck spindle? Does it sound fine, but just not load?

When its making strange noises, this site might help you decide exactly what has happened with a close listen to the drive:

A lot of times these noises mean you are toast, or in for a costly repair & data recovery job.  If you have backups, this can serve for great entertainment to satisfy your inner geek.  You’ll know exactly what happened…

Without backups, well, at least you can add the exact diagnosis to your new data loss nightmare story.  But those stories are getting REALLY old these days, so please make sure you are getting good backups, there is no good excuse.


Virtual Office and working from anywhere

I’m happy to say I can now officially work from anywhere. Its a great feeling, and I am really enjoying this beautiful weather. Can you get out and do that efficiently today?

I can truly:

  • Answer all calls on my office phone – via my software phone on my laptop.
  • Make all calls with my office caller id with my softphone – caller id says I’m in the office to customers, so what if there are birds in the background.
  • Access all my data on the virtual office system, outlook anywhere, & external sites via the internet
  • Enjoy this beautiful weather!
  • Have the freedom to sit down and work ANYWHERE with my verizon air card & laptop.

Can you work from anywhere? Call us today for more information how you can free yourself from the confines of a traditional office environment. You deserve this level of efficiency and ease of technology access.  We can help you drive your business ahead of the curve.  This is easy, and its time you took advantage of it.

why don’t I have an iPhone?

I’ve been struggling with this question from customers constantly since its introduction, and I still might have get one just to prove myself wrong, but I just do not see the BUSINESS benefit to an iPhone vs. a simple blackberry curve.  I can crank through contacts, calendar and messges fast on the blackberry.   Don’t see that happening on the iPhone.

Looks like I’m not alone:

I agree with that article.


Lets hear it from you:

Are you keeping cool and efficient?

I’m happy to report I have not really needed the air conditioning in my home office this year.  The weather in NJ has been fantastic lately, and its already july 8th!

On of the ways I’ve been able to keep my office cool is by taking advantage of windows Vista’s ability to SLEEP.  yes, it works, and works almost as well as a MAC!  go figure.  Between that and our virtual office system, I can work much more efficiently and cooler!

I recommend trying it if you are running vista, and while you are at it, check out some of these other power saving tips.  Many of them will help you manage your heat too!

“10 power-saving myths debunked “