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VMDKs and Snapshots


tips and tricks for creation and repair of virtual disks ...
when it is too late
disktypes-table ...
often used procedures ...


translating VMware-button-names to common sense ...

 

What happens when you take a snapshot ?

You already know the term: snapshot - it usually means something like: take a photo in the middle of an action ...
Imagine you watch your little daughter climbing up a ladder - on step 5 she falls down - and in the precise moment she falls you take a photo. Wow - you now have a photo that shows your little daughter flying in the air.
You can show this snapshot to all her aunts and uncles ;-)
Lets get serious again. Does the photo matter ?
Nope - the moment of the snapshot is the breakpoint between to actions:
- climb up the ladder
- fall down.
In VMware-reality you can go back to the snapshot.
Actually you can go back to the end of the "climb ladder action" and have a second trial for the "fall down action".
This time dont stare at her - run ...

With VMware these actions are just files.

A virtual machine writes into a vmdk.
So what does "take a snapshot" mean ?
Very simple: finish the current vmdk and write into a new one.
Full stop - that's all.

finish current vmdk/redo-log keep current REDO-log keep
discard current REDO-log discard
merge current REDO-log with parent merge
start to write into a new vmdk/redo-log start new REDO-log
 append
start new REDO-log
(append to selected parent)

 append to selected

We got three ways to finalize the current vmdk and two ways to start a new one.
This adds up to some nice variants of combining our options.
See your self
VMware button label fileoperation simplified description
(imagine you are an author
and write a book)
     
Take Snapshot close and keep current REDO-log
start new REDO-log		 finish current chapter
start a new chapter
Revert to Snapshot
(special case of Goto)		 discard current REDO-log
start new REDO-log		 restart last chapter
Delete merge current REDO-log with parent
start new REDO-log		 define last chapter as good and keep it
start a new chapter
Goto discard current REDO-log
start new REDO-log
(append to selected parent)		 discard last chapter
start over from chapter X
keep all different versions
     
Linked Clone start new REDO-log
(append to selected parent)
use with a new VM (vmx-file)		 start a different version of the book using
the first X chapters of the main version
Full Clone merge current branch into a copy in a new dir
use with a new VM (vmx-file)
copy the complete book and work on the copy
keep the original as it is
     
a disk in
non-persistent mode		 start new REDO-log
discard it at next exit		 doesn't matter what you write
you will discard this chapter anyway


 

 


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