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Re: [Xen-tools] Re: [Xen-devel] [PATCH] Make xend reject duplicates and

To: Christian.Limpach@xxxxxxxxxxxx
Subject: Re: [Xen-tools] Re: [Xen-devel] [PATCH] Make xend reject duplicates and rename zombies
From: Anthony Liguori <aliguori@xxxxxxxxxx>
Date: Fri, 16 Sep 2005 16:49:58 -0500
Cc: Xen Tools Developers <xen-tools@xxxxxxxxxxxxxxxxxxx>, Xen Developers <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Christian Limpach wrote:

On 9/16/05, Anthony Liguori <aliguori@xxxxxxxxxx> wrote:
I think renaming would make sense if a domain is crashed.  You might
want to keep the domain around to attach a debugger to it but at the
same time restart a fresh copy as soon as possible.
As long as you can make sure to rename *after* all of the devices have
been properly torn down.

Otherwise, we need to make sure to make it well known that restarting a
domain after a crash can result in very bad things :-)

How so?  The crashed domain is certainly not going to do anything with
those devices anymore...  Actually, I'm not even sure I buy the
"unsafe to reuse devices" argument if the domain is only hanging
around in an almost dead state -- it's almost dead, it's not going to
do any requests on those devices anymore...
I'm thinking specifically about block devices. While the domain may have died, there may be requests in the block devices queues that have not been flushed to disk yet. This is what would lead to problems..


Anthony Liguori

So regarding the check for termination in check_name, if we only
switch the state to terminated once the domain is almost dead, reusing
the name should be fine...


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