Dynamically Expanding Virtual Hard Disk Option for Vmware Esxi

Hi Expert:
Can you tell me if VMware EXSI has a "Dynamically Expanding Virtual Hard Disk" function likes in Microsoft Virtual PC or Virtual Server? Or any other similar feature?

I need to create several testing Database servers in VMware ESXI and it required me to allocation all the space upfront. Unlike the Virtual Server, all I need to use is Dynamically Expanding HD function. Im just start to use ESXI moving from MS Virtual Server 2005 R2.

Thank you in advance for your help.
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bluedanAsked:
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kichigaijinConnect With a Mentor Commented:
Bluedan,

I've got the answer to your question, but let me just add a warning:  while what you want to do--use dynamically-sized disks--is simple and easy to implement, it's only good from that standpoint. In the longer run--and even on many test systems--it's better to pre-allocate disk space.  Performance and manageability are the two major reasons why.

BTW, in VMware-speak, what you are asking for is a "thin-provisioned disk" or just "thin" disk.  Creating one will be a two-step process of first creating the virtual disk and then referring to it within the VI client to provision your VM.

So, onward...  

1)  This can't be done using the VI client or RCLI with the free version that I can tell.  I also use ESXi 3.5 update 3 free version.  You'll need to access the console using "Tech-Support" mode ==> http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003677

2)  Once logged in, create a thin disk using "vmkfstools":  

  vmkfstools -c <size> -d thin /path/to/datastore/<virtual_disk_name>.vmdk

Same thing with more concrete values:

  vmkfstools -c 10G -d thin /vmfs/volumes/datastore1/test_vm.vmdk

vmkfstools will provide you with what you need.  Just typing the command w/o arguments will display a list of options.  BTW, don't be fooled that typing "ls -lh" shows that "test_vm-flat.vmdk" is a full 10G (in my example.)  It's only showing the max file size.  Use "df -h" to see the actual (lack of much) change in used file system space.  BTW, also using the "thick" option to "vmkfstools" to create a test .vmdk and then doing "df -h" should satisfy you on that point...

3)  When provisioning the VM using the VI client, do a "Custom" installation and when it gets to that point, select the "Use an Existing Virtual Disk" option in the "Select a Disk" dialog.  Finish provisioning the VM and you'll have what you want.

But again, don't do it on a production machine.  Or on a test system that will be used for performance optimization.  
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bhanukir7Commented:
Hi,

The default is to allocate the disk space for the disks, otherwise you can specify the disk size and uncheck the option

"allocate disk space now"

the VMDK files work the same way as it works in MS virtual server

bhanu
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bluedanAuthor Commented:
Hi Bhanu, I did not see the option when creating a new HD. As soon as I added a new HD, it will take space from the datastore, even if I have not yet put anything to that new HD. Can you provide me more information?? In MS Virtual server, the VHD will just grow based on the data I put there.

Thanks!
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bhanukir7Commented:
Hi,

how are you creating the VMs are you using the VI client or are you using remote command line functions to create the VMs.

I will post the screen shots on how to create the VMs with dynamically growing disks.

bhanu
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bhanukir7Commented:
Hi,

my apologies,  I misinterpreted your post. I was taking the question more on the front where the disk space is allocated for the VMs.

The differencing disk method in VMware terms is referred to as creating link clones and this is possible only on VMware Server and VMWare workstation.

The same feature is not available in ESX.

bhanu
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bhanukir7Connect With a Mentor Commented:
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bluedanAuthor Commented:
Hi bhanu:

Some background info.

I'm currently using VMware ESXi Free version. I connect to ESXI via VI client.

Thank you for point out the differencing disk method. Its good to know that it will not work on ESXI. But, I'm interested in "dynamically expanding disks" or "dynamically growing disks" function. Just to carify you can refer to tech note below?

About dynamically expanding disks in MS Virtual Server 2005
http://technet.microsoft.com/en-us/library/cc708315.aspx 

I have tried to create new VM or adding Virtual Disk to existing VM. However, in both case, it will just allocated the full disk size upfront to the datastore I picked. I'm not sure if its support in the free version of ESXi.

Thanks,

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bhanukir7Commented:
hi bluedan,

The dynamically expanding disks & dynamically growing disks have only a different name in vmware. I did work a lot on MS virtual server, rather i started working on it first then moved to VMware.

As updated when you create a VM the size is reduced from the VM datastore but if you check the size of the data on the Storage drive you will see that it has not created a file of that size.

This is not  a limitation in ESXi but is also in ESX 3.xxx versions.

bhanu
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bluedanAuthor Commented:
Hi bhanu:

Thank you for the speedy response. Actually, it also created the virtual Disk file of that size when I went to the Storage drive. I tested on 3 times and it all did the same thing. BTW, I'm on the lastest version - ESXI 3.5 Update 3.

Would you kindly provde me a step by step or screenshots on how to get the dynamically expanding disks working in ESXI just like it would in Virtual Server 2005.

Thank you again!
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