vmdk.flat

[Spiker]

Can someone please explain why I see both a .vmdk and a .vmdk-flat file in the browser

They both have the same size and I know from checking the console that only 1 of those files is using space

[Dave_Mishchenko]

see this thread: http://www.vmware.com/community/thread.jspa?messageID=570821&#570821

[esiebert7625 · Accepted solution]

vmdk files – These are the disk files that are created for each virtual hard drive in your VM. There are 3 different types of files that use the vmdk extension, they are:

o *–flat.vmdk file - This is the actual raw disk file that is created for each virtual hard drive. Almost all of a .vmdk file's content is the virtual machine's data, with a small portion allotted to virtual machine overhead. This file will be roughly the same size as your virtual hard drive.

o *.vmdk file – This isn't the file containing the raw data anymore. Instead it is the disk descriptor file which describes the size and geometry of the virtual disk file. This file is in text format and contains the name of the –flat.vmdk file for which it is associated with and also the hard drive adapter type, drive sectors, heads and cylinders, etc. One of these files will exist for each virtual hard drive that is assigned to your virtual machine. You can tell which –flat.vmdk file it is associated with by opening the file and looking at the Extent Description field.

o *–delta.vmdk file - This is the differential file created when you take a snapshot of a VM (also known as REDO log). When you snapshot a VM it stops writing to the base vmdk and starts writing changes to the snapshot delta file. The snapshot delta will initially be small and then start growing as changes are made to the base vmdk file, The delta file is a bitmap of the changes to the base vmdk thus is can never grow larger than the base vmdk. A delta file will be created for each snapshot that you create for a VM. These files are automatically deleted when the snapshot is deleted or reverted in snapshot manager.

[Spiker]

Thanks guys for clearing that up !

[saunders]

How come the *-flat.vmdk file is the exact same size as the *.vmdk file? Shouldnt the *.vmdk file be a tiny fraction of the size of the *-flat.vmdk file?

Thanks for any help.

Saunders

[Dave_Mishchenko]

The VI client doesn't display the size of vmdk file correctly, and if you connect via SSH and run ll in the VM's folder you'll see that the vmdk file is quite small.

[oreeh]

This simply is a display bug in the datastore browser.

[jrico82]

I don't agree with you, oreeh. Because, I'm not able to create a 300GB VM in a Datastore with 500GB available disk space. It is a very serious issue because there is a lot of money wasted since the vm's size is duplicated.

Regards.

[Dave_Mishchenko]

If you're not able to create the vmdk with that size, it is likely that the data store was formated with a block size of 1 MB. That block size only always files up to 256 GB. If you need larger, you would need to reformat the data store. A 2 MB block size will allow vmdk files up to 512 GB, 4 MB = 1024 GB and 8 MB = 2048 GB. You can't change the block size once the data store is created so the only option if you need a 300 GB vmdk is to reformat it.

[jrico82]

Opps...!http://communities.vmware.com/message/796493/!! Thanks to let me remember this.

I have faced this issue several times (flat.vmdk=vmdk) and when the datastore reaches 100 GB available disk space, I'm not able to create a 70 GB virtual machine.

[AlbertWT]

Hi All,

Got a quick question of why everytime i create a new VM through "custom" method and by pointing the Hard Disk to the existing .VMDK in vmname dir. it will end with creating vmname_1 directory ?

the same thing also applies when I start the VM from another ESXi as failover test, it is also creating another vmname_1 directory instead of starting the VM inside the same directory.

Cheers.

[satishchirala]

VMDK file supports upto 256 GB ONLY

[satishchirala]

Please find the attachment for Clear Differences while creating a vm , Snapshot , Second Snapshot.

vmdk files – These are the disk files that are created for each virtual hard drive in your VM. There are 3 different types of files that use the vmdk extension, they are:

o     *–flat.vmdk file - This is the actual raw disk file that is created for each virtual hard drive. Almost all of a .vmdk file's content is the virtual machine's data, with a small portion allotted to virtual machine overhead. This file will be roughly the same size as your virtual hard drive.

o     *.vmdk file – This isn't the file containing the raw data anymore. Instead it is the disk descriptor file which describes the size and geometry of the virtual disk file. This file is in text format and contains the name of the –flat.vmdk file for which it is associated with and also the hard drive adapter type, drive sectors, heads and cylinders, etc. One of these files will exist for each virtual hard drive that is assigned to your virtual machine. You can tell which –flat.vmdk file it is associated with by opening the file and looking at the Extent Description field.

o     *–delta.vmdk file - This is the differential file created when you take a snapshot of a VM (also known as REDO log). When you snapshot a VM it stops writing to the base vmdk and starts writing changes to the snapshot delta file. The snapshot delta will initially be small and then start growing as changes are made to the base vmdk file, The delta file is a bitmap of the changes to the base vmdk thus is can never grow larger than the base vmdk. A delta file will be created for each snapshot that you create for a VM. These files are automatically deleted when the snapshot is deleted or reverted in snapshot manager