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xen-devel
Re: [Xen-tools] Re: [Xen-devel] [PATCH] Make xend reject duplicates and
Christian Limpach wrote:
On 9/15/05, Anthony Liguori <aliguori@xxxxxxxxxx> wrote:
I think this is not the right solution to the problem at hand. The
problem stems from the fact that xm destroy is just a call to
xc_domain_destroy which is really just a request to the hypervisor to
destroy the domain.
Indeed.
Therefore, there is a race condition if you assume that the domain is
dead after xm destroy returns. This patch renames the domain name which
prevents a name class but does not solve the general problem. Consider,
for instance, if a domain is using a block device and you do an xm
destroy. It is not safe to create a new domain with that same block
device until you know that the previously mentioned domain is gone.
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 :-)
Regards,
Anthony Liguori
This patch would allow:
xm destroy xmexample1 && xm create /etc/xen/xmexample1
I think the right solution is to make xm destroy not return until the
domain has actually gone away and add a flag to xm destroy to return
immediately if that behavior is ever desired.
Sounds good.
I'll work up a patch tonight after class.
Thanks!
christian
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