I put together a white paper recently explaining some of the performance tradeoffs of using vmware thin vmdks vs going thin on the back end with a system that understands eager zero thick vmdks. Thin provisioning is a broad topic that covers a style of allocating resources. This is required to reclaim space back from the virtual disk. A full guide on how to convert vhd to vmdk for free. Will thin provisioned vms shrink automatically just as they would grow automatically. Currently, vmware does not have automatic space reclamation, unless youre running a san which supports this and you have the necessary components installed, such as equallogics hitkit.
When i look at the drive through the datastore browser it tells me the actual size is 7 gb and the provisioned size is 40 gb. Converting vmware workstation thick disks vmdks to thin recently, i built a new machine for my lab for those interested in the story, here are parts i, ii and iii. For example, if you create a new thinprovisioned 30gb virtual disk and copy 10 gb of files to it, the size of the resulting vmdk file will be 10 gb, whereas you would have a 30gb vmdk file if you had chosen to use a thickprovisioned disk. Thin provisioned disks are a great feature to save capacity as you virtual machines filesystem will never use the full capacity. When you create a virtual machine, a certain amount of storage space on a datastore is provisioned to virtual disk files.
It will continue to occupy the maximum space it have ever used after creation. Before we can use vmkfstools to shrink the vmdk file we must zero out any unused space on the thin provisioned disk. The method of changing disk provisioning type using cli involves copying current vmdk file to a new thin provisioned disk and removing old thick disk. By default, esxi offers a traditional storage provisioning method for virtual machines. It came as a surprise to me that the datastore file browser in vsphere 6. When we use thin provisioned vmdk, the size of the vmdk expands as we pile up data in the os. Jun 29, 2009 you can use the storage vmotion feature on a vmdk and reclaim the unused space in this way, but remember that only empty space that has not previously been written to by the guest os can be reclaimed. Monitor the use of space on thin provisioned luns to avoid running out of physical space. You can use the storage vmotion feature on a vmdk and reclaim the unused space in this way, but remember that only empty space that has not previously been written to by the guest os can be reclaimed. How to reclaim size of a thin provisioned vmdk file in. I put a 512gb ssd in the new machine with the aim to thinprovision all virtual machines but still get good performance, due to the high number of iopsreadwrite you get from. Before they go with the project to inflate all thin provisioned disks or migrate to thick provisioned lazy zeroed they needed to know how much additional storage. Reclaiming unused vmdk space with storage thin provisioning. Click the folder that contains the file that you want to download.
Nov 07, 20 before we can use vmkfstools to shrink the vmdk file we must zero out any unused space on the thin provisioned disk. Sparse file is realization of thin provision ideology for individual files, rather than. Jun 02, 2014 this video shows perfectstorage running a reclaim operation in an esxhosted windows server 2008 guest in order to shrink a thin provisioned vmdk. Recently one of my colleagues was downloading virtual machines from esxi to his windows 7 laptop and we ran into a strange problem. It is quite a popular topic in virtualization and san. Vaai thin provisioning block reclaimunmap in action. Hi all, recently one of my colleagues was downloading virtual machines from esxi to his windows 7 laptop and we ran into a strange problem. Also, if youre doing it on a thin provisioned disk, youll have vm. Shrinking thinprovisioned esxi disks miscellaneous.
Download sdelete onto the vm you want to shrink and run the following command, replacing drive. Thinprovisioned virtual disks are quick to create and useful for saving storage space. You can verify the disk type from the virtual machine settings page. This article gives the steps to convert a thick provisioned virtual hard drive vmdk to thin provisioned on esx 4 or newer. This is a default behaviour, even if the initial vmdk file was thinprovisioned and the target datastore supports thin provisioning. Accessing the files direcly via scp or download via. Added a 10 gb thin provisioned vmdk to a windows 2003 virtual machine. Click storage in the vmware host client inventory and click datastores. But if we delete some data from os, the reclaimed space in the os will not be reclaimed from the vmdk. This powercli script takes a vm, fills the disks with zeros and then moves the vm between two datastores. When you have some vms with thin provisioned disks, you may have noticed that these will continue to grow, and never shrink, even after cleaning out data from within the vm.
Move vmware esxi vm to new datastore preserve thinprovisioning. Use the datastore file browser to download files from the datastores available on the host that you are managing to your local system. The space savings from using thin provisioning can be considerable and so, where possible, its advisable to use it or to consider converting from thick to thin. This commandline tool has a powerful feature which can track and zero unused blocks. To do this the virtual machine needs to be powered off.
Download files from a datastore to your system in the. This is for esxifree, so vcenter is not available, no vmotion, no storage vmotion. Monitor the use of space on thinprovisioned luns to avoid running out of physical space. Reducing the size of a thick provisioned vmdk without. If youve thinprovisioned a vmdk under esxi and need to reduce it for whatever reason, the official vmware documentation suggest to migrate the vm to another datastore using vmware converter which is not always practical, thankfully an alternative exists. May 06, 2017 thinprovisioned disks never shrink automatically when you delete data from it, lets learn how to do it. Vmdk2phys convert a virtual disk vmdk in a physical disk. Possibly the biggest issue that we have with thin provisioning is running out of space on a device that is thin provisioned at the backend. Please note that i dont want to focus on reclaiming space from underlaying luns. I have a virtual machine with a 10 gb thin provisioned disk. Convert a vmdk from thick to thin on esx bonus bits.
That style is to allocate a small amount of actual resources to start and only reserve more resources as actual growth occurs. Next, we deployed a virtual machine with a 15gb vmdk to this datastore. Note that some methods of cloning preserve thin provisioning and some do not. Once a block has been written to, it is always inuse even when you delete the file. For example, if you create a new thin provisioned 30gb virtual disk and copy 10 gb of files to it, the size of the resulting vmdk file will be 10 gb, whereas you would have a 30gb vmdk file if you had chosen to use a thick provisioned disk. Thin provisioning is a space reduction technique that optimizes the amount of storage physically assigned to servers, reserving space only for data written to disk. For example, if you create a new thin provisioned 30gb virtual disk and copy 10 gb of files to it, the size of the resulting vmdk file will be 10 gb, whereas you. Nov 24, 2014 howto shrink a thin provisioned virtual disk vmdk.
Windows deletes a file by removing the referencespointers in the file allocation table. Could someone explain or point out a tutorial on moving a thinprovisioned vmdk from the datastore on one server to the datastore on another. Thin provisioning is another type of storage preallocation. Im only talking about shrinking thinprovisioned disks. Mylibrary if you created a virtual disk in the thin format, you can convert the thin disk to a virtual disk in thick provision format. Home vmware, vsphere, vsphere 5 how to shrink a thin vmdk on esxi 5. Reducing the size of a thick provisioned vmdk without vmotion, copy or clone. When you work with a thin disk provisionned vm, you are copying new files into a vm, then deleting them, again and again, this process grow the thin disks over time. I do not know a single system where you do not have at least 10gb of free space for os disks. Using sdelete and vmkfstools to reclaim thin vmdk space using thin provisioned virtual disks can provide many benefits.
Solved question on how a thin provisioned disk grows. As your datastore grows or if you use storage vmotion to migrate virtual machines to a thinprovisioned lun, the host communicates with the lun and warns you about breaches in physical space and about outofspace conditions. This video shows perfectstorage running a reclaim operation in an esxhosted windows server 2008 guest in order to shrink a thinprovisioned vmdk. Migrate the vm guest to another datastore and change the advanced configuration of the hard drive to thin provisioned. Could someone explain or point out a tutorial on moving a thin provisioned vmdk from the datastore on one server to the datastore on another. Converting vmware workstation thick disks vmdks to thin. A simple way of doing this is by using a free utility called sdelete from sysinternals.
Backing up a vmdk volume involves copying the virtual disk to a new location. In the vmware case, if you create a thinprovisioned disk, its going to grow. I see a lot of questions and answers surrounding thin provisioning on vmware esxi but not exactly what im encountering. A similar technique can be used to shrink thinprovisioned guest hard disks. Vmware powercli script to list thin provisioned virtual disks vmdk one of my clients was concerned about the number of virtual machines that were built with thin provisioned disks. With this method, you first estimate how much storage the virtual machine will need for its entire life. The inflated virtual disk occupies the entire datastore space originally provisioned to it.
From all ive read, im expecting the physical size of the vmdk file to be less than 100gb. Thin provisioned disks and sparse files at vmfs datastores. As your datastore grows or if you use storage vmotion to migrate virtual machines to a thin provisioned lun, the host communicates with the lun and warns you about breaches in physical space and about outofspace conditions. To be able to reduce the vmdk file size of your thinprovisioned. May 14, 2018 now make sure that the type of the disc is changed to thin provision. Last time i tried it, i think this does preserve the vmdk format. If you created a virtual disk in the thin format, you can convert the thin disk to a virtual disk in thick provision format. Vmware advanced vmdk size reclamation for thinprovisioned disks. Physical space taken is dependant on thick or thin provisioning, thick will be the same size as the disk, thin will be only the. Vmware vmdk shrink and storage thin provisioning 101.
Not only do they allow overprovisioning, but with the prevalence of flash storage, performance degradation really isnt a concern like it used to be. How to release unused blocks from a thinprovisioned vmdk. Will thinprovisioned vms shrink automatically just as they would grow automatically. Now sdelete has finished, we need to run vmkfstools on the datastore to shrink the thin provisioned vmdk back down to size. Determine the vmfs disk space a thin provisioned virtual machine. Vmdk files can be mapped mounted to the specified mount point on your host machine if vmware workstation is installed. It took with it a 300gb partition that was thin provisioned. The disk needs to be around 4gb, however, most of the time the files written on it wont occupy mor. However, when you try to download the vmdk file via the vsphere web client. Provisioning virtual machine with the given requirement is a simple task but if any requirement to change the configuration of provisioned virtual machine in future would be bit complex task. To shrink a vmdk we can use an esx command line tool vmkfstools, but first you. Howto convert a vmdk from thick to thin provisioning on. This post demonstrates various ways to identify the disk usage of a thin provisioned virtual disk. In vcenter, i add an empty secondary hard disk thin provisioned to an existing virtual machine.
On closer inspection i found out that the vmdk was taking up 40 gb of space even though it is setup to do thin provisioning and the windows installation only took about 7 gb. Thin provisioned virtual disks are quick to create and useful for saving storage space. Option 1 migrate the vm guest to another datastore and change the advanced configuration of the hard drive to thin provisioned. Identify disk usage of a thin provisioned virtual disk. To shrink a thinprovisioned vmdk the guest filesystem has to be zeroed out. Nov 23, 2014 this post demonstrates various ways to identify the disk usage of a thin provisioned virtual disk. Demystifying vmware thin provisioning searchstorage. Changing thick or thin provisioning for vmdk vmware hdd. I just migrated it to a new host, and noticed that is using 187gb on my datastore. Lets take an example you have been given a task to create a virtual machine with one vmdk disk of thin provisioned format. Downloading vmdk virtual disk and descriptor file to open. Reclaim disk space from thin provisioned vmdk files in esxi server. Vmware powercli script to list thin provisioned virtual.
While thin provisioning adds storage as needed, it does not work in reverse, removing unneeded storage for the vm. How to release unused blocks from a thin provisioned vmdk. Here is a look at the provisioned and used space from a vmdk perspective. Vmdk virtual disks can be divided into the following types and variations. I am creating a brand new vm and specifying a 100gb thin provisioned hard disk. If you just download the disk using vsphere client or the. Oct 16, 2018 it came as a surprise to me that the datastore file browser in vsphere 6. For example, if you wrote 10gb of data to a thinprovisioned disk and then deleted it, although from the vms perspective the space is now free, from the perspective of the physical disk that the thinprovisioned vmdk is provisioned on the 10gb of data is still there.
Now the 50gb is thin provisioned but actual size of the vmdk file is only 1. And for new vmfs5 datastores could be a big problem because they use a unified block size of 1mb. Delta vmdk disks are created when taking vm snapshots. This will just reduce the vmdks usage on the vmfs datastore not resize the provisioned size of a thin disk. This is because thin provisioning can be considered as a vmfs file system feature. If you delete files from within the vm wanting to gain the space back, it just dont work. The 50gb drive is the one i am trying to restore so as a test i deleted the 50gb disk from the datastore with a plan to restore it its just a test vm i setup for this purpose. Zero free space using sdelete to shrink thin provisioned vmdk. The vms had their disks created as thin provisioned and when we try to download it, it would download the entire capacity of the disk. Download files from a datastore to your system in the vmware. Check the properties of the vmdk through the web management, when you edit it, look next to the disk2. Now make sure that the type of the disc is changed to thin provision. A thin provisioned virtual disk consumes only the space that it needs initially, and grows with time according to demand. Using sdelete and vmkfstools to reclaim thin vmdk space.
Some things should be simple, shrinking a thin provisioned virtual disk should be one of them, its not. From all ive read, im expecting the physical size of the vmdk. This will just reduce the vmdk s usage on the vmfs datastore not resize the provisioned size of a thin disk. It doesnt matter if you move between vmfs3 or vmfs5, if you try to force the thin conversion, of if you try to converter to thick and then to thin seems that you need different block size to reclaim the zeroed blocks in a thin vmdk. Jul 24, 20 when we use thin provisioned vmdk, the size of the vmdk expands as we pile up data in the os.
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