Re: [Qemu-devel] [PATCH] Create the VMDK snapshot from the QEMUmonitor.

From: Fabrice Bellard <fabrice@bellard.org>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] Create the VMDK snapshot from the	QEMUmonitor.
Date: Tue, 09 Jan 2007 20:40:22 +0100	[thread overview]
Message-ID: <45A3EFA6.6010207@bellard.org> (raw)
In-Reply-To: <64F9B87B6B770947A9F8391472E0321609E93740@ehost011-8.exch011.intermedia.net>

Ideally, it would be better to use bdrv_pread() and bdrv_pwrite() (see 
how they are used in block-qcow*.c).

Regards,

Fabrice.

Igor Lvovsky wrote:
> Hi Anthony,
> 
> I wrote the patch before Fabrice introduced his solution and I didn't look at it before I sent my patch (my mistake). 
> But you are right; the new snapshot infrastructure can be useful.
> I'll modify my code for new approach and I hope Fabrice will accept it.
> 
> As for CID, I think that snapshot tag it's something else.
> The CID in VMDK is value updated on the first write every time the virtual disk is opened.
> 
> By the way, I have a question:
> I want to use the standard pread()/pwrite() functions instead of 
> pair:
> 	lseek()
> 	read() / write()
> 
> I know that this may do some problem for Windows implementation,
> but I can use some kind of define for Windows case.
> A question is if it's acceptable.
> 	
> 		Regards,
> 	Igor Lvovsky
> 
> 
> 
> 
> -----Original Message-----
> From: qemu-devel-bounces+igor.lvovsky=qumranet.com@nongnu.org [mailto:qemu-devel-bounces+igor.lvovsky=qumranet.com@nongnu.org] On Behalf Of Anthony Liguori
> Sent: Tuesday, December 26, 2006 7:25 PM
> To: qemu-devel@nongnu.org
> Subject: Re: [Qemu-devel] [PATCH] Create the VMDK snapshot from the QEMUmonitor.
> 
> Hi Igor,
> 
> Out of curiousity, why didn't you use the new snapshot infrastructure 
> that Fabrice introduced in CVS?  Shouldn't the CID just map directly to 
> a snapshot tag?
> 
> Regards,
> 
> Anthony Liguori
> 
> Igor Lvovsky wrote:
> 
>>  Hi,
>>
>>This patch completes the previous one and allows the snapshot (VMDK 
>>style) creation from the QEMU monitor (Ctrl+Alt+2).
>>
>> 
>>
>>To clarify, the previous patch implements the snapshot capabilities 
>>according to the "Virtual Disk Format 1.0" document.
>>
>>http://lists.gnu.org/archive/html/qemu-devel/2006-12/msg00311.html
>>
>> 
>>
>>Implemented features:
>>
>>   1. Create snapshot.
>>   2. CID concept to prevent snapshots chain inconsistency.
>>   3. Snapshots read/write capabilities.
>>
>> 
>>
>>The whole chain (base image and snapshots) created by QEMU can be 
>>loaded from the VMware workstation and vice versa.
>>
>> 
>>
>>Igor Lvovsky.
>>
>>------------------------------------------------------------------------
>>
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>>Qemu-devel mailing list
>>Qemu-devel@nongnu.org
>>http://lists.nongnu.org/mailman/listinfo/qemu-devel
>>  
> 
> 
> 
> 
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