Hello.
I have two questions about restore VM to ESXi server and VSS.
I.
This page http://pubs.vmware.com/vsphere-50/index.jsp?topic=%2Fcom.vmware.vddk.pg.doc_50%2FvddkBkupVadp.9.6.html says:
“Windows 2008 application level quiescing is performed using a hardware snapshot provider. After quiescing the virtual machine, the hardware snapshot provider creates two redo logs per disk: one for the live virtual machine writes and another for the VSS and writers in the guest to modify the disks after the snapshot operation as part of the quiescing operations.
The snapshot configuration information reports this second redo log as part of the snapshot. This redo log represented the quiesced state of all the applications in the guest. This redo log must be opened for backup with VDDK 1.2 or later. The older VDDK 1.1 software cannot open the second redo log for backup.”
My problem that I cannot find any of files with “.redo” extension neither on the datastore near the other VM files, nor inside the ESXi server disk, nor inside of the guest OS. Even properties of a snapshot MOR doesn’t contain anything similar to .redo log info, but it only has fields like “quiesced” and “backupManifest”.
The only idea I have – both of that redo logs are encapsulated inside of incremental virtual disk file (vmdk), which was created during snapshot.
Am I correct here?
My configuration:
- guest OS is Windows Server 2008 R2;
- VMware tools with “Volume Shadow Copy Services Support” are installed;
- disk.EnableUUID parameter is set to true;
- virtual disk type is SCSI;
- VDDK library version is 1.2
II.
This question is about restore and VSS.
“Restore must be done using the backup application’s guest agent.”
“Create a Temporary Snapshot on the Target Virtual Machine
…
Another flag named memory allows you to include in the snapshot a dump of the powered on virtual machine's in-memory state. This is not needed for backup, so set this flag to False.”
First, how the backup process goes:
1. Backup application creates a snapshot with parameters bool memory=false, bool quiesce=true
2. In this time VMware Tools VSS support component sends command for VSS–aware applications to put data into it’s files. So applications data files are in conststent state for the moment of backing up.
3. Backup application saves VM configuration and state of disks from snapshot, vss_manifests.zip.
On restore (VM as a copy):
1. Backup application creates new virtual machine from a saved VM config.
2. Backup application writes the contents of created disks with a backed up info.
The power state of new restored VM is “powered off”.
Data files of VSS-aware applications are in consistent state.
When VM will be powered on, VSS-aware applications will succeed to load its data files and continue proper work.
So my question is: considering the above facts, why for is VSS restore agent required, what are its functions?
Thanks in advance
Alexey Barabash