[vbox-dev] quiesce disk

Geoff Nordli geoffn at gnaa.net
Thu Jun 16 20:06:17 GMT 2011

>From: Klaus Espenlaub
>Sent: Thursday, June 16, 2011 12:13 PM
>On 16.06.2011 19:23, Geoff Nordli wrote:
>> Is there a way to quiesce a disk to take a file system snapshot?
>Pausing a VM implicitly completes all outstanding async I/O requests, which
>includes the dirty parts of the cache.

Thanks, that is the information I am looking for.   

>> If you are using cached i/o then it would need to flush the cache as
>The guest has its own cache, and we don't have control over that...
>So the result of taking a snapshot will be an image of limited consistency.
This is
>the reason why a proper snapshot of a VM includes the entire state of the
>system, including RAM, device state and so on.

Yes, that makes sense, because you have no control what is going on inside
the Guest OS, like a database for example.  Anything that happens in the
guest which needs consistency needs to be taken care of separately.  

Have a great day!


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