vmware - disk provision

Posted on 2014-02-05
Last Modified: 2014-02-14
Can some one explain the difference between the following specially

thick provision eagar zeroed
thick provision lazy zeroed

also what is use of vmware tools?
is it really needed for vm? what is the function of this tool?
Question by:ittechlab
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LVL 121

Accepted Solution

Andrew Hancock (VMware vExpert / EE MVE^2) earned 167 total points
ID: 39836171
thick provision eagar zeroed  - storage space for the virtual machine disk is allocated, at virtual machine disk creation, and ALL the blocks in the VMDK are ZEROED!

It makes for a faster performing disk, because the VM, does not have to zero the block before writing.

thick provision lazy zeroed - same as above, but the blocks are not zeroed.

thin disk - space allocated is dynamic and grows with use of the virutal machine disk, until the maximum defined size is reached. it can be slow, and does not perform as well as the first disk type - thick provision eagar zeroed

"What are VMware Tools?

VMware Tools are a suite of utilities that enhances the performance of the virtual machine's guest operating system and improves management of the virtual machine. Installing the VMware Tools package will greatly enhance graphics and mouse performance in your virtual machine. Without VMware Tools installed in your guest operating system, guest performance lacks important functionality. You can check if you have VMware Tools installed by checking the Summary of your virtual machine using the vSphere Client if using VMware vSphere 4.x or 5.x, or ESX/ESXi 4.x, 5.x. If VMware Tools are installed VMware Tools will read OK, an IP Address and DNS hostname will appear in the Summary page."

from my EE Article:-

Part 8: HOW TO: Install VMware Tools for Windows on a VMware Windows virtual machine on a VMware vSphere Hypervisor 5.1 (ESXi 5.1) Host Server
LVL 12

Assisted Solution

by:Alex Green
Alex Green earned 166 total points
ID: 39836179
Thick provisioned, takes all the space straight away on the lun so nothing else can use it

Thin assigned a 40gb drive to the VM but doesn't reserve the space

Eager and lazy - lazy-zeroed, ESXi doesn't zero each disk block until it is first accessed by the VM. When using eager-zeroed, ESXi will zero each disk block immediately after the creation of the disk.

Basically it eager could give you better performance but not really needed.

Rule of thumb though, thin over thick every time, you get more out of your SAN. Downside, you have to monitor it so you don't over provision by too much.

EDIT - You changed your question as well, VMWare tools basically allow better responsiveness when using the console as well as assisting with migrations to other hosts (I think)
LVL 13

Assisted Solution

Abhilash earned 167 total points
ID: 39836184
Thick provision means all the space designated for the virtual disk files is reserved when the VM is created.

Thick provision Lazy zeroed means that blocks containing older data on the storage device are only cleared/Or raw disk is zeroed when the virtual machine writes new data to the disk for the first time.

Thick provision Eager zeroed means that blocks containing older data on the storage device are only cleared/Or raw disk is zeroed when the virtual machine the disk is created.

Thin provisioned will not no space is reserved. The disk is filled when the VM writes the data.

Check the below link for overview of VMware tools
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Author Comment

ID: 39836295
is it better to use thin or thick eager zeroed when setting up a new VM.
LVL 13

Expert Comment

ID: 39836346
If you use thin it will save you space but the performance will be lesser than thick as the disks are zeroed and then data is filled every time you write.
If space is no issue, Go with disk.
If performance is not important go with thin
LVL 121
ID: 39836347
thick eager zeroed - always!
LVL 121
ID: 39836358
@alexgreen312 You can migrate VMs using vMotion without VMware Tools!

Author Comment

ID: 39836694
my SAN admin told me that HP recommend to use Thick eager provision for all VMs.
It does not make sense to me. You guys have any idea.

Author Comment

ID: 39836702
People arguing that VMware tools is must for vMotion. not make sense to me.
LVL 13

Expert Comment

ID: 39836733
This is what the HP Documentation says

Block Zeroing uses the standard SCSI command WRITE_SAME to offload large, block-level write
operations of zeros from the host to the storage array. Block zeroing improves host performance and
efficiency when allocating or extending Eager Zeroed Thick (EZT) virtual disks, or on initial access to
a block on a non-EZT virtual disk. When combined with built-in zero-detection and EZT virtual disks,
storage array bandwidth, disk I/O bandwidth, and disk consumption is minimized. Initialization of
EZT virtual disks in seconds rather than minutes eliminates the tradeoff between fast VM creation and
fast run-time performance.

So yes it makes sense to have Eager zero disks.
And yes it does not make sense that VM-tool is required for vmotion. That's a wrong statement.

Author Comment

ID: 39836748
Can you please point the HP document?

Author Comment

ID: 39836763
Can you point out some scenarios where it would be more appropriate to use these three technologies.

thick provision eagar zeroed
thick provision lazy zeroed
LVL 121
ID: 39837284
thick provision eagar zeroed - performance critical VMs, VMs using for Fault Tolerence or Clustering.

thick provision lazy zeroed - Virtual Machines, where performance is no so critical, but to be honest, why not use thick provision eagar zeroed, and get 15% better performance.

thin - when you are short of disk space, Lab and Test environments. But be careful, ALL your VMs, do not dynamic allocate, and use ALL the disk space, because then you will over subscribe your storage space.

Most NFS datastores, would use Thin disks. Be careful Thin disks are not supported by some vendors for Applications e.g. Microsoft Exchange

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