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Eager/Lazy Zeroed

I would like someone to explain clearly what they mean by Eager Zeroed and Lazy Zeroed in Vmware vernacular.

if you back it up with an example it will be much helpful

Thank you
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jskfan
Asked:
jskfan
5 Solutions
 
Tony GiangrecoCommented:
Thick Provision Lazy Zeroed
Create a virtual disk in a default thick format. Space required for the virtual disk is allocated during creation. Any data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.

Thick Provision Eager Zeroed
Create a thick disk that supports clustering features such as Fault Tolerance. Space required for the virtual disk is allocated at creation time. In contrast to the flat format, the data remaining on the physical device is zeroed out during creation. It might take much longer to create disks in this format than to create other types of disks.

https://pubs.vmware.com/vsphere-50/index.jsp#com.vmware.vsphere.vm_admin.doc_50/GUID-B13C46B5-979C-4E41-9088-25AD78FF41B8.html?resultof=%2522%2545%2561%2567%2565%2572%2522%2520%2522%2565%2561%2567%2565%2572%2522%2520%2522%255a%2565%2572%256f%2565%2564%2522%2520%2522%257a%2565%2572%256f%2522%2520
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Vaseem MohammedCommented:
In Lazy zero blocks are reserved but not formatted/cleared for new data. As the data comes in, the blocks are zeroed and new data is written.

In Eager Zero, blocks are reserved and formatted/cleared and ready to write new data

That's the reason why it takes time for Eager Zeroed virtual disk type to be created than Lazy zeroed virtual disk.
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RickEpnetCommented:
In theory the Eager Zero should be faster that Thin or Lazy Zero.  In practice the difference is not really noticeable. However unless you are pressed for time if you are going to use Thick I would use Eager. Why not pay the price upfront of writing to the blocks instead of having your application or OS pay the price while it is running.
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Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
There are good articles written here by fellow vExpert Frank Denneman, which discusses Storage DRS, and time taken to Storage DRS (Storage vMotion) different disks types!

http://frankdenneman.nl/2012/12/19/thin-or-thick-disks-its-about-management-not-performance/

http://www.yellow-bricks.com/2012/12/19/death-to-false-myths-the-type-of-virtual-disk-used-determines-your-performance/

which came about from these articles discussed by other fellow vExpert Eric Sloof

http://www.ntpro.nl/blog/archives/2241-Mythbusting-Disk-provisioning-type-doesnt-affect-performance.html

I would give them all a read, because it's also now storage related, e.g. what type of SAN, and technology do you use.
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jskfanAuthor Commented:
***if the storage is brand new, no data in it…the lazy and eager zeroed still applies..??

*** is lazy/eager zeroed new term in vmware Vsphere or it has been used in the previous versions of Vmware ??
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
***if the storage is brand new, no data in it…the lazy and eager zeroed still applies..??
- Yes, it based on the creation of the VMDK.

*** is lazy/eager zeroed new term in vmware Vsphere or it has been used in the previous versions of Vmware ??

These terms have been around for many years, in terms of VMDK format, but not always available from the GUI, or able to create the disks from scratch via a wizard!
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jskfanAuthor Commented:
Thank you
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
12% Performance Increase if you use Eager Zero - tested!
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