What are Thin Disks,Thick Disks

Excellent explanation of various storage technologies, especially Thin disks from vmmba.

 There are three main technologies that can accomplish storage oversubscription:

1. Linked clones
   • This feature is available in VMware Lab Manager and VMware Workstation at the virtual disk level.  When a linked clone is used, the new VM uses pointers to the original VM for all common data.
   • The additional advantage of linked clones is that whitespace is not stored – for example if an empty data disk is part of a clone operation, the new disk will act as a "thin" disk and only consume the storage that it really requires for data
   • Linked clones can also be accomplished at the datastore level using technologies such as NetApp FlexClone (useful when cloning many VMs at once)
   • Keep in mind: linked clones pay a performance penalty on write operations (using copy-on-write), and put added stress on the source disks on read operations
2. Thin Disks
   • Thin-provisioned disks are virtual disks that "appear" to the VM as one size, but only consume up to the amount of data that is required by that disk.  So, a 10 GB drive that is 50% utilized will only store 5 GB on disk (a traditional "thick" virtual disk would consume the entire 10 GB on disk)
   • Thin disks are options in VMware Workstation, and are the default disk type when using NFS storage in VMware ESX Server – however, VMs cloned from templates are always thick
   • Storage vendors such as Hitachi and NetApp have LUN-level thin provisioning, but that would only apply to VMware if using RDMs
3. Deduplication
   • Deduplication is a technology similar to memory page sharing (above), where common data is stored only once.  It is done "after the fact" (ex poste), meaning de-duplication opportunities are scanned using a background process
   • Deduplication is primarily used for backups (e.g. Symantec PureDisk, EMC Avamar, or Quantum DXi-Series), but can also be used on the filesystem itself (today, using NetApp Deduplication, formerly A-SIS)

REFERENCE: www.vmmba.com

VM Provisioning -02

Cloning a VM is equivalent to deploying VM from template. Here as well you get option to customize guest OS. To clone VM, simply right click VM, say clone this VM. In order to enable Guest OS customization.

In order to enable guest OS customization, you need to configure Virtual center. Download latest sysprep tool from Microsoft, this customization applies only for Windows,for Linux it is inbuilt. Launch the installer and extract the contents to C:\Documents and Settings\All Users\Application Data\Vmware\VMware VirtualCenter\sysprep1.1

Some folders as per OS configuration are already created under this folder, extract them into respective folders.

Guest OS customization would look like

1) Enter Name and Organization

2) Guest OS Name, you have various option to select from, Select as per your organization’s policy

3) Enter Product ID and License information

4) Enter Administrator Password, also in the same screen if you would like Admin to logon and how many times, you select.

5) Pick up appropriate time zone

6) Run once keep default

7) Workgroup or domain select as per your organization policy

8) Operating system options

Generate SID’s

Delete all user accounts

9) In the end you have option to save customization for later use and it finishes OS customization part.

MORE INFORMATION:

http://pubs.vmware.com/vi301/wwhelp/wwhimpl/js/html/wwhelp.htm

VM Provisioning

Template is used for provisioning of VM’s in VMware. Provisioning is inbuilt feature in VMInfra 3.0. Technically Template is a VM which cannot be powered ON. Templates/VMDK can be stored in Monolithic form or sparse file format.

What is monolithic or spare file format ?

lets take a example:  If you create a monolithic file format of 16 GB, totally 16 GB is claimed  at one go, But if you create sparse file format 16GB will be consumed as and when it is utilized. Templates can be stored in NFS/SVC Console/VMFS

Templates can be created in two ways

• Clone to template – Original VM is retained.
• Convert to template – converts VM to template

DEPLOY VM FROM TEMPLATE

 Connect to Virtual center via VI client

Change the view to VM and Templates

Right click the template and select deploy this VM from this template.

Wizard will ask you VM’s Name and Host on which you want to put this VM

Next select resource pool

Last you get option to customize OS.

You can select YES /NO depending upon your choices.

1) Select Template

2) Select Datacenter and ESX Host

UPDATING TEMPLATES:

In case you need to include latest Hotfix/Patches into templates, you easily do it. In order to achieve this task. Select template and select convert to virtual machine. Once VM is powered ON, apply patches and etc. Convert the same VM back to template.