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Re: [Xen-API] pygrub-related question

To: Daniel Stodden <Daniel.Stodden@xxxxxxxxxx>
Subject: Re: [Xen-API] pygrub-related question
From: Jonathan Ludlam <Jonathan.Ludlam@xxxxxxxxxxxxx>
Date: Thu, 21 Jan 2010 22:13:12 +0000
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Thread-topic: [Xen-API] pygrub-related question
Generally speaking, as far as xapi is concerned, there's no difference between 
a VHD backed VDI and any other kind - they all get block attached to dom0 for 
any data access. However, IIRC, the HA statefile and the redo log are both 
accessed directly - but this would only be enabled if you've got HA turned on.

Other than that, I don't recall that we ever directly touch raw block devices, 
though I'll check more thoroughly tomorrow.



On 21 Jan 2010, at 21:48, Daniel Stodden wrote:

> Hi.
> When booting PV domains via pygrub, Xapi exclusively accesses the disk
> image through a dom0 plug, right?
> This is obviously the case with images backed by VHDs. I guess it's safe
> to assume this is also the case with raw images. But I'm more or less
> guessing. 
> Does the agent shortcut reads to the bare physical node somewhere?
> Asking because of some page cache invalidation issue we apparently
> haven't come across yet.
> Daniel
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