Backup / Restore of VMware VADP backup sets
Creation Date: April 26, 2010
Revision Date: January 22, 2016
Product: DS‑Client (Linux and Windows)
Summary
This article covers various backup and restore issues for the VMware VADP backup sets.
See Also
Backup of VMware VADP backup sets using CBT (Changed Block Tracking)
DS-Client can use CBT (Changed Block Tracking) for VMware VADP backup sets. If enabled, DS-Client attempts to reconfigure the virtual machine to allow tracking of the blocks of data that have changed. This option can improve the speed of incremental backup activities, but may also slow down the virtual machine since it consumes additional resources.
When CBT is enabled, the first backup activity will scan the virtual machine.
• For ‘thick disks’, the scan will be of the entire virtual machine’s disks.
• For ‘thin disks’, the scan will only cover the space occupied by the disks.
Subsequent backup activities will track the changes for the virtual machine files and will only retrieve the blocks of data that have changes. These blocks will be processed for master/delta generations and sent and saved to DS-System and/or Local Storage.
If CBT fails to be enabled (even if configured for use in the backup set), DS-Client will continue its incremental backup activities by reading the entire data of the virtual machine disks, processing the data for master/delta generations and sending the backup data to DS-System.
Backup / Restore of virtual machine in a cluster
Backup of virtual machines on clustered hosts (VMware cluster) should be done through the VMware vCenter Server. Make sure to enter the IP address of the vCenter Server when creating the backup set. Then you can browse and select the specific virtual machine cluster to backup.
If you back up an individual virtual machine in a VMware cluster by specifying the host IP address when creating the backup set, subsequent backups may fail, depending on the configuration of the cluster.
Normally, a VMware DRS (Distributed Resource Scheduler) cluster’s automation level is configured to be Fully automated for High Availability. This means the individual virtual machines that make up the cluster will be dynamically assigned to the best suited host at startup. This means the virtual machine might be automatically moved to another host when the VMware cluster (or virtual machine) is restarted.
Since you can back up individual virtual machines in a VMware cluster (by specifying the host IP address when creating the backup set), if the virtual machine moves to another host, it will not be found by the backup set and errors will occur. However, if the virtual machine is selected through the vCenter Server, the location of the virtual machine is always known (even if it moves to another host).
If you have to back up a specific virtual machine in a VMware cluster (using a dedicated backup set to a specific host machine’s IP address), you must configure the cluster to not move that virtual machine to different hosts.
• In the Virtual Center, edit the VMware DRS cluster settings: “Enable individual virtual machine automation levels”.
• For the specific virtual machine that you want to back up, change its Automation Level setting to Disabled. This will prevent the vCenter Server from migrating the virtual machine.
NOTE: It is easier to create the backup set by specifying the vCenter Server’s IP address as the source in the New Backup Set Wizard. This allows you to browse and select the specific virtual machine from the cluster and you will not need to change the automation settings for the cluster.
Locking of virtual machines during backup and restore
DS-Client automatically locks the target virtual machine during VMware VADP backups and restores. This will prevent any attempts to delete or migrate the target until the backup or restore process has completed.
Backup of fault tolerant virtual machines
DS-Client cannot back up virtual machines that have fault tolerance (FT) enabled since it depends on making a snapshot of the virtual machine to back it up and VMware does not support snapshot creation on FT virtual machines.
VMware has documented the full procedure for backup / restore of FT virtual machines using templates in their knowledge base article # 1016619.
Restore to Alternate Location (different VMware DataCenter connected to different vCenter Server)
DS-Client must have network access to the vCenter Server and all involved ESXi host(s).
Incremental virtual machine restore of VMware VADP backups
Incremental virtual machine restore for VMWare VADP backup sets is available only in Linux DS‑Client.
Requirements for Incremental virtual machine restore
• You must select the check box Attempt incremental restore in the Restore Now Wizard when initiating a restore session for a VMware VADP backup set. Selecting this option configures the backup set for Incremental virtual machine restore. Otherwise, Linux DS-Client will perform Full virtual machine restore by default.
In the first restore session after a VMware VADP backup set has been configured for Incremental virtual machine restore, Linux DS-Client will perform a Full virtual machine restore, and backup set information will be saved with the restored virtual machine. Then, when you configure a subsequent restore session for that backup set, the check box Attempt incremental restore will remain selected in the Restore Now Wizard, and Linux DS-Client will attempt Incremental virtual machine restore for the backup set in that restore session and onward until you clear this check box.
• The virtual machine must already exist in the target restore destination as a result of a previous virtual machine restore performed by DS-Client.
Recommended practices to aid successful Incremental virtual machine restores
When a virtual machine restored by DS-Client is powered on, VM configuration parameters will likely change. As a result, DS-Client will disallow an
Incremental virtual machine restore and force a
Full virtual machine restore in the next restore session. For more information, see
“VM configuration changes and Incremental virtual machine restore”.
To aid a successful Incremental virtual machine restore in the next session, practice the following recommendations:
• To test a restored virtual machine, clone the virtual machine using VMware tools, and use the cloned virtual machine for testing. Do not test the restored virtual machine directly. This recommendation applies whether the most recent restore of a virtual machine was Incremental or Full.
• Do not power on a restored virtual machine manually or directly in the vCenter Server unless you have decided to use the restored virtual machine as a production machine.
VM configuration changes and Incremental virtual machine restore
Before initiating a restore for a VMware VADP backup set configured for Incremental virtual machine restore, DS-Client compares the backup generation to be restored and the virtual machine at the destination location. If DS-Client detects any differences in VM configuration parameters in a restore session, DS-Client will not perform an Incremental virtual machine restore but force a Full virtual machine restore instead.
FLR (File Level Restore) from VMware VADP backups
File Level Restore (FLR) is a feature for VMware VADP backup sets that allows granular restore of individual files from a VMware VADP backup.
NOTE: In the backup session immediately after the FLR feature is enabled, a full backup of the virtual machines is performed regardless of whether the CBT option is enabled for the backup set. All subsequent backups will be incremental.
Requirements
The FLR option must be turned on before the backup. This is done by selecting Use FLR in the New Backup Set Wizard or Backup Set Properties - Options tab.
Limitations
• The FLR feature works in limited use cases. The following will not work (or may not work properly) with the FLR option:
• FLR & Local Storage
• FLR & Local Only
• FLR from BLM images
• FLR from Disc/Tape
• For Linux DS-Client, FLR can only restore to the local machine (where the DS-User is running). FLR cannot be done to a remote location through SSH, NFS, or NAS.
• For Windows DS-Client, FLR restore can be done to a remote machine.
• For Linux DS-Client, drive letter information will be missing in the DS-User.
• Only Windows DS-Client with NTFS virtual machines will display drive letter information.
Target virtual machine disk formatting and file system limitations
FLR parses the RAW file system. Because of this, FLR is restricted to particular disk formatting styles and file system types for the target virtual machine. FLR supports multiple virtual machines, multiple disks, multiple partitions and file system types, with the following limitations:
Partition Support Table |
Partition Name | Partition Number | supported |
Empty | 0x00 | Yes |
Extended | 0x05 | Yes |
NTFS | 0x07 | Yes |
Linux | 0x83 | Yes |
Single Disk Linux LVM (Linear & Mirror) | 0x8e | Yes |
File System Support Table |
File System Name | Supported |
Ext4 | Yes |
NTFS | Yes |
Notes
• For the Linux LVM partition type (0x8e), FLR supports only the following mapping formats:
• Linear mapping
• Mirror mapping
NOTE: You can check the type of the LVM mapping by using the “lvdisplay –m” command in a Linux environment. Also note that FLR does not support any type of mixed mapping (for example, if you have a logical volume using both Linear and Stripe mapping).
• FLR may fail on corrupted partitions (for example, due to manual changes to a partition type name). To view the configuration of disk partitions of the target backup virtual machine, use any application that provides disk configuration information (like the Disk Management tool in Windows or the Disk Utility tool in Red Hat environments) and view the following:
• partition name, type, and size
• file system type
• bootable and primary partitions
• In the case of an unsupported partition type, FLR shows an empty partition in the DS-User with the name starting with “Unsupported ... partition ...”.
Best practice: Avoid conflicting activities on virtual machines
• Avoid running conflicting activities on the same virtual machine.
• Running multiple clones with Local DS-VDR activities on the same virtual machine from the same or different Local DS-VDR Tools should be avoided. When running conflicting activities, files may be left in the ESXi server which are not registered and not used and they can occupy large amounts of space.
TROUBLESHOOTING: Backup of a migrated virtual machine using the CBT feature gets file fault error
Error
A known issue for VMware VADP backup sets using the CBT feature occurs in a very specific scenario where an incorrectly configured virtual machine is backed up. The following steps describe the situation when this error occurs:
• Migrate a virtual machine using the vCenter Server.
• Back up the migrated virtual machine with a VMware VADP backup set using the CBT feature.
• When you backup, the following error appears:
Error opening file disk2000.vmdk for reading QueryChangedDiskAreas: SOAP 1.1 fault: "":ServerFaultCode [no subcode] "Error caused by file /vmfs/volumes/4ac65eb0-8b20da10-c550-0030483062fe/rhel61thin-test/rhel61thin-test.vmdk" Detail: <FileFaultFault xmlns="urn:vim25" xsi:type="FileFault"><file>/vmfs/volumes/4ac65eb0-8b20da10-c550-0030483062fe/rhel61thin-test/rhel61thin-test.vmdk</file></FileFaultFault> (rhel61thin-test) (VMware VADP\10.20.30.111\\DataCenter\Test\rhel61thin-test\disk2000.vmdk).
Reason
This is because after migration, even though the virtual machine has a property setting of CTKenabled=true, it has not been properly reconfigured by the vCenter Server. If this error occurs, it means the virtual machine has a configuration problem and probably should not be used.
• If this error occurs you must fix the virtual machine with the fix described below.
Fix (after the file fault error is encountered)
One possible fix is to make a modification that triggers the vCenter Server to run a re-configuration cycle on the virtual machine. This can be done by performing the following steps:
1. Power off the target virtual machine.
2. Using the vCenter Server, select the virtual machine and select Edit Settings. The Virtual Machine Properties screen appears.
3. Select the Virtual Disk. In the section Mode, select Independent and click OK.
4. Select the virtual machine again and click Edit Settings. The Virtual Machine Properties screen appears.
5. In the Mode section, clear the check box Independent and click OK.
The vCenter Server should perform a re-configuration of this virtual machine (this may take a few minutes). After re-configuration is finished, power on the virtual machine. You should now be able to back up the virtual machine with the Use CBT feature.
Suggested Best Practice (to prevent the file fault error)
Whenever you migrate a virtual machine using the vCenter Server, always perform the steps in the Fix (above) that will trigger the vCenter Server to run a re-configuration cycle on the virtual machine.