Convert a VMDK from Thick to Thin on ESX

Convert a VMDK from Thick to Thin on ESX

This article gives the steps to convert a thick provisioned virtual hard drive VMDK to thin provisioned on ESX 4 or newer versions.

One method you have is an option to Migrate (say vMotion) the VM Guest to another datastore and change the advanced configuration of the hard drive to thin provisioned or If you can't vMotion or migrate the VM to another datastore you can use this vmkfstool command from the VM host to convert it.

Optional steps to check:

1. Login to the VM Guest
2. Make sure the VMTools are updated
3. Run an OS Defrag of the drives
4. Use Microsoft SDelete 
1. http://technet.microsoft.com/en-us/sysinternals/bb897443
2. Download and install on the VM Guest OS
3. Run sdelete -c

If Powered On VM

1. Power Off the VM Guest
2. Login to the VM Host that has the VM Guest either by Power CLI or SSH
   1. You may need to enable SSH and ESX Shell to do this
3. Browse to the VM Guest file location
   1. Example: cd /vmfs/volumes/mydatastore/vmname/
4. Clone original disk to a thin copy
   1. vmkfstools -i SERVERNAME.vmdk -d thin thin-SERVERNAME.vmdk
5. Rename the original disk
   1. vmkfstools -E SERVERNAME.vmdk orig-SERVERNAME.vmdk
6. Rename the thin disk to the original disk name
   1. vmkfstools -E thin-SERVERNAME.vmdk SERVERNAME.vmdk
7. Remove VM Guest from VM Host inventory
8. Add the VM Guest back to the VM Host inventory
   1. This so the VM Host registers that it's now a thin provisioned disk/s
   2. This may not be needed for vSphere 5
9. Verify that the VM Guest boots and runs correctly
10. Remove original Thick disk/s
1. vmkfstools -U orig-SERVERNAME.vmdk

Reference Sources;

http://communities.vmware.com/thread/296983

Note: In Lab Manager 4 undeploy the VM Guest first. The VM Guest does not need to be removed and re-added because undeploying and deploying essentially does that.

Increasing a VMDK file size using VMKFStools

Increasing a VMDK file size using VMKFS tools

This article provides the steps to extend a Vmware VMDK virtual disk file from command-line with the Vmware utility vmkfstools.

Steps to Follow:

1. Power Off the VM Guest
2. Undeploy the VM Guest if in Lab Manager
3. Remove any snapshots
4. Consolidate if a template in Lab Manager
5. Login to the VM Host Console
6. Change directories to the appropriate path to the VM Guest
   1. Example: cd /vmfs/volumes/<datastore>/<vm guest>
7. Optionally create a backup of the VM disk
   1. Example: vmkfstools -i <vmname>.vmdk -d thin backup-<vmname>.vmdk
8. Extend the disk size
   1. Do Not run the command on the file name with flat. Run it against the smaller meta file that just ends in vmdk.
   2. Example: vmkfstools -X 60G <vmname>.vmdk
   3. The new size will be 60 GB
9. Deploy the VM Guest if in Lab Manager
10. Power On the VM Guest
11. Use a partition management utility if older than Windows Vista/2008 to extend the partition with the new unallocated space in the OS.
12. Remove backup VMDK when satisfied that it was successful.
13. Done

Reerence sources:
http://communities.vmware.com/docs/DOC-2459

Note: If you consolidate a VM guest in Lab Manager it will convert the VMDK files to thick.  So at the end of this process you may want to follow the steps to convert it back to thin which will update soon.

Recover Orphaned Virtual Machines

Recover Orphaned Virtual Machines

Virtual machines appear in the vSphere inventory listed as orphaned appended to their name.

Problem

Virtual machines that reside on an ESXi host managed by vCenter Server might become orphaned in rare cases. Such virtual machines exist in the vCenter Server database, but the ESXi host no longer recognizes them.

Cause

Virtual machines can become orphaned if a host failover is unsuccessful, or when the virtual machine is unregistered directly on the host. If this situation occurs, move the orphaned virtual machine to another host in the datacenter that has access to the datastore on which the virtual machine files are stored.

Solution

1	In the vSphere inventory list, right-click the virtual machine and select Migrate.
2	Click Change Host and click Next.
3	Select the host on which to place the virtual machine. If no hosts are available, add a host that can access the datastore on which the virtual machine's files are stored.
4	Click Finish to save your changes. The virtual machine is connected to the new host and appears in the inventory list.

Increase Memory or CPUs while on Virtual Machine

In Windows 2003/2008 ENT or DC is required as well as the memory/cpu hotplug option in the VM. If you are seeing the setting grayed out, then a power off will be required.

Also ...and while the guest is off you can configure the hot plug options as well... Edit Setting--Options Tab--Memory/CPU Hotplug.

Note: Will Explain Configuration of HotPlug in other Blog

Example Below ScreenShot.

ESX

With VMware Infrastructure Client, connect to the ESX host that is managing the virtual machine or to VirtualCenter Then Follow below steps

• Right-click the entry for the virtual machine.
• Click Edit Settings.
• If not already selected, click the Hardware tab.
• If not already highlighted, click Memory.
• From the window displayed at the right, increase the amount of memory.

This way If you find your VM Memory and CPU settings grade out to make any changes then you need to Power off the VM and open the Edit Settings and select the Hardware Tab and then choose your Devices and make changes to the Memory, Cores and Processors configuration. Click Ok and then Power on the VM.

TO SETUP ACTIVE DIRECTORY ON WINDOWS SERVER 2008

STEP BY STEP GUIDE TO SETUP ACTIVE DIRECTORY ON WINDOWS SERVER 2008

This tutorial will explain how to install AD on server 2008. This will valid for windows 2008 R2 as well.

Recommended Requirement:

Minimum: Single processor with 1.4 GHZ (x64 processor) or 1.3GHz (Dual Core)

Minimum: 512 MB RAM

Minimum: 32 GB or greater

First Step to Follow:

The first step is to assign a ip to the server that you going to deploy the AD. Its necessary to install it as DNS server too. So its better to have fixed ip it doesn't mean you cannot install AD without fixed ip address but it will solve lot of issues if you used fixed ip.



In here the server ip is 10.0.0.14. Since we going to make it as DNS server too you should use the same ip as the preferred DNS server.

NEXT STEP: 

• To install the Active directory roles. Unlikely the older version of windows servers Microsoft highly recommend to use server manager option to install roles before you run dcpromo. 
• Click on start menu and select the Server Manager

• Select the roles from the right hand panel and click on add roles option

From the roles list select the "Active Directory Domain Services" role and Click "Next"

Review the confirmation and click on "Next"

Review the installation confirmation and click on "Next"

It will take few minutes to complete and when its done you will get this confirmation. And then click on "Close"

After that you will need to do a reboot.

After reboot please open up the "server Manager" again. And then click on "Roles" there you will see the "Active Directory Domain Services" is successfully installed in there. click on it then you will get a window like below.

In their please pay attention to the message



So please click on that link and it will start the DCPROMO wizard.

So next step to go through the DC promo wizard.

To start the installation click on "Next"

Click on "Next"

Since we going to install New domain Controller in new forest please select the option "Create a new domain in new forest" option and click on "Next"

Now we have to provide the name for our domain controller. It must be FQDN. In our case I used XXXXXXXX.com as the domain. Please click "Next" after it.

In this window it will ask to select forest function level. If you going to add server 2003 domain controller to your forest later don't select the function level as server 2008. If you going to use full features of 2008 Ad you must select forest function level as server 2008. In my case I used server 2008. Click on "Next" after the select.

In next window since it's the first DC we should make it as DNS server too. Leave the default selection and click on "Next"

If the wizard cannot create a delegation for the DNS server, it displays a message to indicate that you can create the delegation manually. To continue, click "Yes"

In next window it will show up the database location. It its going to be bigger AD its good if you can keep NTDS database in different partition. Click on "Next" after changes.

In next window its asking to define a restore mode password. Its more important if you had to do a restore from backup in a server crash. Click on "Next" after filling it.

Next window is giving you a brief of the installation. Click on "Next"

Then it will start the installation of the AD. It will take some time to complete. After complete of the installation perform a server reboot.

After the reboot now you can login to the domain. Please use the login as following example

User name : your domain\administrator

Password : XXXXXXXX

Now its done and you can view the active directory options on administrative tools menu

Hope this tutorial is clear for you guys. If any question please ask me on chiranjeevi.raj@gmail.com

RESOLVING THE CID MISMATCH ERROR: THE PARENT VIRTUAL DISK HAS BEEN MODIFIED SINCE THE CHILD WAS CREATED (1007969)

Symptoms

• You are unable to power on a virtual machine or consolidate snapshots if a parent file has been modified after the child has been created. This includes base disks and snapshot delta files.
• Depending on the modification or caused mismatch, you see any of these errors:
  • Failed to open 'virtual machine disk' with flags 0xe (The parent virtual disk has been modified since the child was created)
  • Failed to open (The parent virtual disk has been modified since the child was created)
  • Failed to open 'virtual machine disk': The parent virtual disk has been modified since the child was created (18).
  • DISKLIB-LINK : Attach: Content ID mismatch (7b7644b2 != 4f5a6761)
  • DISKLIB-LINK : Attach: the capacity of each link is different (83886080 != 46399652).
• You see this error in the vSphere Client:
  
  Cannot open the disk '/vmfs/volumes/4a365b5d-eceda1-19-439b-000cfc0086f3/examplevm/examplevm-000001.vmdk' or one of the snapshot disks it depends on.
Reason: The parent virtual disk has been modified since the child was created.
• The virtual machine log contains entries similar to:
  
  vmx| DISKLIB-LINK : Attach: Content ID mismatch (d0fdb25b != ef4854ee).
vmx| DISKLIB-CHAIN : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm.vmdk" : failed to open (The parent virtual disk has been modified since the child was created).
vmx| DISKLIB-VMFS : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002-delta.vmdk" : closed.
vmx| DISKLIB-VMFS : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000001-delta.vmdk" : closed.
vmx| DISKLIB-VMFS : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-flat.vmdk" : closed.
vmx| DISKLIB-LIB : Failed to open '/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002.vmdk' with flags 0xa (The parent virtual disk has been modified since the child was created).
vmx| DISK: Cannot open disk "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002.vmdk": The parent virtual disk has been modified since the child was created (18).
vmx| Msg_Post: Error
vmx| [msg.disk.noBackEnd] Cannot open the disk '/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002.vmdk' or one of the snapshot disks it depends on.
vmx| [msg.disk.configureDiskError] Reason: The parent virtual disk has been modified since the child was created.----------------------------------------
vmx| Module DiskEarly power on failed.
• The virtual machine shuts down abruptly during snapshot removal, deletion, or commit.
• The virtual machine shuts down abruptly during or immediately following a Storage vMotion or Migration.
• You see this error when attempting to power on a virtual machine:
  
  A general system error occurred: Internal error.
• Performing a snapshot removal or powering on the virtual machine generates the error:
  
  Content ID mismatch
• If you grow an RDM mounted inside a virtual machine while the snapshot is being committed, you may see errors similar to:
  
  DISKLIB-LINK : DiskLinkIsAttachPossible: the capacity of each link is different (262144000 != 52428800)
  /vmfs/volumes/<datastore-name>/<vm-name>/<vm-name>.vmdk" : failed to open (The capacity of the parent virtual disk and the capacity of the child disk are different)
  DISKLIB-VMFS : "./<vm-name>-000002-delta.vmdk" : closed.
  DISKLIB-VMFS : "/vmfs/volumes/<datastore-name>/<vm-name>/<vm-name>-000001-delta.vmdk" : closed.
  DISKLIB-VMFS : "/vmfs/volumes/datastore/<vm-name>/<vm-name>-rdm.vmdk" : closed.
  DISKLIB-LIB : Failed to open '<vm-name>-000002.vmdk' with flags 0x17 The capacity of the parent virtual disk and the capacity of the child disk are different (67).
  Failed to open <vm-name>-000002.vmdk' : The capacity of the parent virtual disk and the capacity of the child disk are different (67)

Purpose

This article provides information and troubleshooting steps to diagnose Content ID mismatch conditions between two or more virtual disk files for a virtual machine.

Note: The procedure to correct parent CID and CID mismatch explained in this article is valid for both VMFSSPARSE and SESPARSE type delta disks.

Resolution

Overview

The Content ID (CID) value of a virtual machine disk descriptor file aids in the goal of ensuring content in a parent virtual disk file, such as a flat or base disk, is retained in a consistent state.

The child delta disks that derive from that base disk's snapshot contain all further writes and changes. These changes depend on the source disk to remain intact.

A virtual machine disk descriptor file details the basic geometry, format, or otherwise identification and handling for a virtual disk or virtual disk delta file. A CID resides in each virtual machine's disk descriptor file for integrity or state tracking.

Example descriptor file for a base disk: examplevm.vmdk: # Disk DescriptorFile version=1 CID= 7b7644b2 parentCID=ffffffff createType="vmfs" # Extent description RW 20971520 VMFS "examplevm-flat.vmdk" # The Disk Data Base #DDB ddb.toolsVersion = "0" ddb.adapterType = "lsilogic" ddb.geometry.sectors = "63" ddb.geometry.heads = "255" ddb.geometry.cylinders = "1305" ddb.uuid = "60 00 C2 9f ae de ba e9-95 4e a7 a6 4e 95 c1 c1" ddb.virtualHWVersion = "4"

Example descriptor file for a delta disk examplevm-000001.vmdk: # Disk DescriptorFile version=1 CID= 69a1c662 parentCID= 7b7644b2 createType="vmfsSparse" parentFileNameHint="examplevm.vmdk" # Extent description RW 20971520 VMFSSPARSE "examplevm-000001-delta.vmdk" # The Disk Data Base #DDB ddb.toolsVersion = "7302"

Note: examplevm-000001.vmdk refers to, and in another sense depends on, examplevm.vmdk.

When the virtual machine references a virtual disk, it cites either the base disk's descriptor file, or a snapshot delta's descriptor file. In this example, the virtual machine configuration file, or examplevm.vmx, refers to the delta disk descriptor file:

scsi0:0.present = "true"
scsi0:0.fileName = "examplevm-000001.vmdk"
scsi0:0.deviceType = "scsi-hardDisk"

Any time a virtual machine is powered on, the referenced base or delta disk descriptor file's CID value is changed (see CID printed in blue, above):

examplevm-000001.vmdk before power-on: CID= 69a1c662 parentCID=7b7644b2

examplevm-000001.vmdk after power-on: CID= 6aff3ba2 parentCID=7b7644b2

All of this details a virtual machine in good running condition. A mismatch can be found here, which prevents tasks from succeeding for this virtual machine:

examplevm.vmdk: CID= 12a9ffab parentCID=ffffffff

examplevm-000001.vmdk: CID=69a1c662 parentCID= 7b7644b2

In effect, a CID mismatch ensures that deviance from the original disk state results in all dependent child delta content being invalidated. This protects stored data from further potential corruption.

Cause

Content ID mismatch conditions are triggered by interruptions to major virtual machine migrations such as Storage vMotion or Migration, VMware software error, or user action.

These Content IDs are only used for virtual machine disks with snapshots. For more information about snapshots, see Understanding virtual machine snapshots in VMware ESXi and ESX (1015180).

Some scenarios to avoid in particular include:

• Interrupting a virtual machine migration or Storage vMotion. For more information, see After cold migration of a virtual machine, base virtual disks with snapshots have a CID mismatch (1005228).
• Adding snapshotted virtual machine disks to other virtual machines and powering them on.
• Expanding, enlarging, or modifying virtual machine disks with existing snapshots. For more information, see A virtual machine cannot boot after resizing a base virtual disk that is part of a snapshot hierarchy (1646892).

Troubleshooting

When there is a CID mismatch, the virtual machine name is provided in the error message, but you must identify:

• what virtual machine disk or disks are affected
• what specific disk descriptor files are affected
• the cause of the mismatch, or what changes occurred

Identifying the virtual machine disk and descriptor files affected

There are several methods to log into an ESX host to review content of utilized datastores, depending on the version of ESX utilized. For more information, see Editing configuration files in VMware ESXi and ESX (1017022).

Notes:

• The datastore browser provided in the VMware vSphere Client or VMware Infrastructure Client do not distinguish between virtual machine descriptor (1) and flat or delta files (2). They are collapsed into singular entities to make datastore browsing simpler. As you need to distinguish between the two files, use the additional access methods provided in the referenced article.
• The web-based Datastore Browser, accessible via https://server-ip, is used to browse VMFS datastores and distinguish between the virtual machine descriptor files and their corresponding associated binary files. You can copy the relevant file from the Datastore Browser for editing. The edited file can be uploaded to the datastore again via the vSphere Client.
• Due to the nature of the problem experienced, the quickest method for resolving the issue is with the Command Line Interface available on the individual ESX host. Utilize this method if you have sufficient background knowledge on command-line usage. Alternatively, you can use the VMware vSphere Command Line Interface (CLI) or VMware vSphere Management Assistant appliance (vMA) to obtain the virtual machine disk descriptor files for review.
• If you are unable proceed, please file a support request with VMware Technical Support. For more information, see Filing a Support Request in My VMware (2006985).

After locating the virtual machine's files and directory:

1. The virtual machine's vmware.log file contains information which identifies the specific disk chain affected. Review the logs and note the location and files affected.
   
   Example:
   
   vmx| DISKLIB-LINK : Attach: Content ID mismatch (d0fdb25b != ef4854ee).
vmx| DISKLIB-CHAIN : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm.vmdk" : failed to open (The parent virtual disk has been modified since the child was created).
vmx| DISKLIB-VMFS : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002-delta.vmdk" : closed.
vmx| DISKLIB-VMFS : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000001-delta.vmdk" : closed.
vmx| DISKLIB-VMFS : "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-flat.vmdk" : closed.
vmx| DISKLIB-LIB : Failed to open '/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002.vmdk' with flags 0xa (The parent virtual disk has been modified since the child was created).
vmx| DISK: Cannot open disk "/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002.vmdk": The parent virtual disk has been modified since the child was created (18).
vmx| Msg_Post: Error
vmx| [msg.disk.noBackEnd] Cannot open the disk '/vmfs/volumes/4a365b5d-eceda119-439b-000cfc0086f3/examplevm/examplevm-000002.vmdk' or one of the snapshot disks it depends on.
vmx| [msg.disk.configureDiskError] Reason: The parent virtual disk has been modified since the child was created.----------------------------------------
vmx| Module DiskEarly power on failed.
   Note: This indicates that the file examplevm-000002.vmdk references its parent (which in itself references another parent file), one of which has been modified some time after examplevm-000002.vmdk was created. You must take corrective measures on any of these files: examplevm.vmdk, examplevm-000001.vmdk , and examplevm-000002.vmdk.
2. With the problem point (or points) determined, make backup copies of the disk descriptor files that require corrections or editing. In the example above, backups of examplevm.vmdk, examplevm-000001.vmdk , and examplevm-000002.vmdk are required.
3. Review the contents of each affected descriptor file and compare the mismatching values. For example:
   
   

   examplevm.vmdk: CID= 12a9ffab parentCID=ffffffff

   examplevm-000001.vmdk: CID=69a1c662 parentCID= 7b7644b2

   examplevm-000002.vmdk: CID=59fab513 parentCID=69a1c662

   
   Disk examplevm-000002.vmdk links to examplevm-000001.vmdk without error. However, the base disk examplevm.vmdk has been modified, causing the error.

Note: The number sequences of the VMDK files are irrelevant. For example:

File              CID    PID
XXX.vmdk          1      ---------
XXX-000002.vmdk   2      1
XXX-000001.vmdk   3      2
The VMDK files forms a valid chain, though the XXX-000002.vmdk file precedes the XXX-000001.vmdk file within the chain.

Correcting the Content ID mismatch

At this point, the problem point has been identified, the virtual machine's files have backups, and corrections must be applied.

To correct the Content ID mismatch:

Warnings:

• The CID mechanism is in place to prevent data corruption. Depending on the changes incurred upon the parent file or files, the guest operating system may be unable to boot successfully even after making corrections. A backup recovery should be made available for such circumstances.
• The steps outlined here are potentially hazardous for your environment if they are not followed exactly. If you are not comfortable performing these steps, contact VMware Technical Support and work with them to resolve the issue.

1. Confirm that the disks reference each other:
   
   

   Example descriptor file for a base diskexamplevm.vmdk: # Disk DescriptorFile version=1 CID= 12a9ffab parentCID=ffffffff createType="vmfs" # Extent description RW 20971520 VMFS " examplevm-flat.vmdk" # The Disk Data Base #DDB ddb.toolsVersion = "0" ddb.adapterType = "lsilogic" ddb.geometry.sectors = "63" ddb.geometry.heads = "255" ddb.geometry.cylinders = "1305" ddb.uuid = "60 00 C2 9f ae de ba e9-95 4e a7 a6 4e 95 c1 c1" ddb.virtualHWVersion = "4"

   Example descriptor file for delta diskexamplevm-000001.vmdk: # Disk DescriptorFile version=1 CID= 69a1c662 parentCID= 7b7644b2 createType="vmfsSparse" parentFileNameHint= "examplevm.vmdk" # Extent description RW 20971520 VMFSSPARSE "examplevm-000001-delta.vmdk" # The Disk Data Base #DDB ddb.toolsVersion = "7302"

   Example descriptor file for child delta disk examplevm-000002.vmdk: # Disk DescriptorFile version=1 CID=59fab513 parentCID= 69a1c662 createType="vmfsSparse" parentFileNameHint= "examplevm-000001.vmdk" # Extent description RW 20971520 VMFSSPARSE "examplevm-000002-delta.vmdk" # The Disk Data Base #DDB ddb.toolsVersion = "7302"

   
   Note: The linking or chain references are highlighted in blue. This example shows that examplevm-000002.vmdk as a child ofexamplevm-000001.vmdk, which in turn is a child of examplevm.vmdk. These three disk files make up a singular virtual disk from the perspective of the virtual machine and guest operating system.
2. Using a text editor, correct the mismatch at either of the two problem points. For more information, see Preferred Editors in Editing configuration files in VMware ESXi and ESX (1017022). You may either correct examplevm.vmdk, per this example, or the examplevm-000001.vmdk disk file. In either circumstance, the parentCID and CID relationship must be valid.
   
   Example: examplevm.vmdk can have its CID changed to 7b7644b2, making it match examplevm-000001.vmdk's expected parentCIDvalue. Alternatively, examplevm-000001.vmdk's parentCID value can be changed to 12a9ffab to match examplevm.vmdk's base disk descriptor file's CID. You may also consider creating a CID value on your own.
   
   Note: The CID consists of eight (8) hexadecimal lower-case digits (00000000-ffffffff) with no delimiter characters.

Verifying the CID corrections

The corrections made to the virtual machine files are usually not immediately acknowledged in the remainder of the product. As such, subsequent power-on attempts may not succeed as yet.

To verify the CID corrections:

1. Log into the VMware vSphere Client or VMware Infrastructure Client.
2. Select the virtual machine in the Inventory and click the Summary tab.
3. Under Resources, right-click the datastore that contains the virtual machine's configuration file and select Browse. The Datastore Browser opens.
4. Locate the virtual machine's directory and files. You can minimize it for now, as it will be used in step 7.
5. Right-click the virtual machine and choose Remove from inventory.
6. When prompted, confirm your selection by clicking Yes. The virtual machine disappears from the inventory on the left.
7. Restore the Datastore Browser from step 4, right-click the virtual machine's configuration file (for example, examplevm.vmx), and choose Add to Inventory.
8. Follow the on-screen prompts to bring the virtual machine back into the inventory.
   
   Warning: Do not power on the virtual machine unless you have a valid copy or backup of all of its files. When the virtual machine has been powered on, further irreversible changes are applied to the disk structure.
9. When ready, power on the virtual machine and verify the guest operating system's status. A file system integrity check may be performed to seek out and repair any complications that arise from the disk chain changes that caused the initial CID mismatch.

You can also verify if the CID mismatch has been corrected by running this command against the highest level snapshot .vmdk :

vmkfstools -q snapshot_ xxxxxx#.vmdk -v10 | less

or

For ESXi 5.x:

vmkfstools -e snapshot_ xxxxxx #.vmdk

Note:

• If there are failed messages in the results, the CID mismatch has not been corrected or there is still a mismatch in the snapshot hierarchy.
• The virtual machine must be powered off to run -e option, otherwise it will return the following error -
  Failed to lock the file (16392)Disk chain is not consistent : Failed to lock the file (16392)

Alternative procedure

At this point, the virtual machine should start successfully if the changes incurred were minimal. The guest operating system can exhibit varying symptoms, depending on what occurred in the snapshot.

However, if the virtual machine is not in an acceptable state, you may be required to restore from a backup copy. If one is not available, you can consider starting the virtual machine on older disks.

Example: The virtual disk referenced for the provided example is examplevm-000002.vmdk . If necessary, the virtual machine's configuration file can be modified to boot from examplevm-000001.vmdk, permanently invalidating examplevm-000002.vmdk. This may allow the guest operating system to proceed as intended, but at the cost of losing all information contained in the examplevm-000002.vmdk delta file.

You can log into a VMware ESX or VMware Command Line Interface to edit the virtual machine's configuration file, and you can copy the file from the datastore for editing on another system using a preferred text editor.

For additional information on this topic, see Editing configuration files in VMware ESXi and ESX (1017022).

If you are unable proceed, please file a support request with VMware Technical Support. For more information, see Filing a Support Request in My VMware (2006985).

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Additional Information

• If the virtual machine is powered off and an attempt is made to consolidate the snapshots, the vmware.log file will not contain the reason for the failures. In this case, the hostd.log file is located at /var/log/ on the ESXi host where the affected virtual machine is registered on.
  
  In ESXi 5.x, instead of reviewing the logs, use the vmkfstools -e command to quickly identify the problem:
  
  The error shows the parent and child are affected
  
  For example:
  
  # vmkfstools -e APU-ESB-01-000001.vmdk
  Disk link /vmfs/volumes/5303d209-b32fa2a0-edb9-0017a477c480/APU-ESB-01_1/APU-ESB-01-000001.vmdk successfully opened.
  Disk link /vmfs/volumes/5303d209-b32fa2a0-edb9-0017a477c480/APU-ESB-01_1/APU-ESB-01-000002.vmdk successfully opened.
  Disk link /vmfs/volumes/5303d209-b32fa2a0-edb9-0017a477c480/APU-ESB-01_1/APU-ESB-01.vmdk successfully opened.
  Cannot establish parent(/vmfs/volumes/5303d209-b32fa2a0-edb9-0017a477c480/APU-ESB-01_1/APU-ESB-01.vmdk)-child(/vmfs/volumes/5303d209-b32fa2a0-edb9-0017a477c480/APU-ESB-01_1/APU-ESB-01-000002.vmdk) relationship : The parent virtual disk has been modified since the child was created. The content ID of the parent virtual disk does not match the corresponding parent content ID in the child (18)
  Parent link description
  Name: /vmfs/volumes/5303d209-b32fa2a0-edb9-0017a477c480/APU-ESB-01_1/APU-ESB-01.vmdk
  Create Type: vmfs
  Capacity: 26843545600
  Content ID: 1894300628
  Parent Content ID: 4294967295
  Child link description
  Name: /vmfs/volumes/5303d209-b32fa2a0-edb9-0017a477c480/APU-ESB-01_1/APU-ESB-01-000002.vmdk
  Create Type: vmfsSparse
  Capacity: 26843545600
  Content ID: 1894300628
  Parent Content ID: 3919862208
  Disk chain is not consistent : The parent virtual disk has been modified since the child was created. The content ID of the parent virtual disk does not match the corresponding parent content ID in the child (18)

• This error can also occur with virtual machines running on the VMware Workstation product. The methods described here are valid for that environment, but it is necessary to use the Workstation utility vmware-vdiskmanager.exe program on a Windows system in place of the vmkfstools command.

RefferenceArticle: 

http://kb.vmware.com/selfservice/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=1007969