Xen devel - May 2007 - Should "xm restore" be able to create two domains with the same name?

If I do "xm save dom file", followed by "xm restore file; xm
restore
file", I get two domains with the same name. Surely, that''s not
quite
right? [Particularly since they both will be using the same disk-image,
etc]. 

--
Mats



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On 18/5/07 14:49, "Petersson, Mats" <Mats.Petersson@amd.com>
wrote:
> If I do "xm save dom file", followed by "xm restore file; xm
restore
> file", I get two domains with the same name. Surely, that''s
not quite
> right? [Particularly since they both will be using the same disk-image,
> etc]. 
You shouldn''t do that. ;-)

The second restore ought to fail when xend (or the hotplug scripts) realise
that the block device is already in use.

 -- Keir



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On Fri, May 18, 2007 at 02:55:22PM +0100, Keir Fraser
wrote:
> 
> 
> 
> On 18/5/07 14:49, "Petersson, Mats"
<Mats.Petersson@amd.com> wrote:
> 
> > If I do "xm save dom file", followed by "xm restore
file; xm restore
> > file", I get two domains with the same name. Surely,
that''s not quite
> > right? [Particularly since they both will be using the same
disk-image,
> > etc]. 
> 
> You shouldn''t do that. ;-)
> 
> The second restore ought to fail when xend (or the hotplug scripts) realise
> that the block device is already in use.
The second restore ought to fail before it gets anywhere near hotplug
scripts. XenD should be enforcing name & UUID uniqueness when creating
guest VMs.  Even ''xm create'' lets you start the same guest
twice

http://lists.xensource.com/archives/html/xen-devel/2007-04/msg00279.html

Dan.
-- 
|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
|=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=| 

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> -----Original Message-----
> From: Keir Fraser [mailto:Keir.Fraser@cl.cam.ac.uk] 
> Sent: 18 May 2007 14:55
> To: Petersson, Mats; xen-devel
> Subject: Re: [Xen-devel] Should "xm restore" be able to 
> create two domains with the same name?
> 
> 
> 
> 
> On 18/5/07 14:49, "Petersson, Mats"
<Mats.Petersson@amd.com> wrote:
> 
> > If I do "xm save dom file", followed by "xm restore
file; xm restore
> > file", I get two domains with the same name. Surely,
that''s
> not quite
> > right? [Particularly since they both will be using the same 
> disk-image,
> > etc]. 
> 
> You shouldn''t do that. ;-)
Yes, I _KNOW THAT_. But as you may be aware, I''m not infallible
(unfortunately, I have FAR too much evidence of my fallibility) - and I
expect other people using Xen may not be either ;-) [In this case, I
didn''t realize I had already done a restore after rebooting the system
-
because I don''t have ANY display on the actual domain, and I only
realized after I did "xm list" a while later.]
> 
> The second restore ought to fail when xend (or the hotplug 
> scripts) realise
> that the block device is already in use.
Yes, it does (I realize after reading the xend.log). But the error
isn''t
reported back to the user, and the domain is still kept alive after
it''s
been refused access to the disk. 

But I''m also concerned that if I try "xm create" with the
same name
twice, it complains that the domain already exists. Should "xm
restore"
do the same check to see if a domain by that name already exists and
stop creating the second same-name-instance?

Further, I have two SLES9.3 HVM domains that I''ve successfully logged
into  - they are distinctly different domains, but using the same single
SLES9.3 image that I''ve got [this was an INTENTIONAL attempt to make
this happne, rather than an accident the first time round]. I''m not
sure
why xend didn''t discover that this wasn''t going to work. 

I just saw Dan''s post on the ability to create multiple instances, so
obviously, this has changed relatively recently... 

--
Mats
> 
>  -- Keir
> 
> 
> 
> 
> 


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On 18/5/07 15:08, "Daniel P. Berrange" <berrange@redhat.com>
wrote:
> The second restore ought to fail before it gets anywhere near hotplug
> scripts. XenD should be enforcing name & UUID uniqueness when creating
> guest VMs.  Even ''xm create'' lets you start the same
guest twice
True. Only question is how that would interact with localhost live
migration.

 -- Keir


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> -----Original Message-----
> From: Keir Fraser [mailto:keir@xensource.com] 
> Sent: 18 May 2007 15:43
> To: Daniel P. Berrange
> Cc: Petersson, Mats; xen-devel
> Subject: Re: [Xen-devel] Should "xm restore" be able to 
> create two domains with the same name?
> 
> 
> 
> 
> On 18/5/07 15:08, "Daniel P. Berrange"
<berrange@redhat.com> wrote:
> 
> > The second restore ought to fail before it gets anywhere 
> near hotplug
> > scripts. XenD should be enforcing name & UUID uniqueness 
> when creating
> > guest VMs.  Even ''xm create'' lets you start the same
guest twice
> 
> True. Only question is how that would interact with localhost live
> migration.
But isn''t that exactly why it''s being renamed to
"migrating-<oldname>"
when it''s being migrated? Or did I miss something again?

--
Mats
> 
>  -- Keir
> 
> 
> 
> 


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> -----Original Message-----
> From: Daniel P. Berrange [mailto:berrange@redhat.com] 
> Sent: 18 May 2007 15:08
> To: Keir Fraser
> Cc: Petersson, Mats; xen-devel
> Subject: Re: [Xen-devel] Should "xm restore" be able to 
> create two domains with the same name?
> 
> On Fri, May 18, 2007 at 02:55:22PM +0100, Keir Fraser wrote:
> > 
> > 
> > 
> > On 18/5/07 14:49, "Petersson, Mats"
<Mats.Petersson@amd.com> wrote:
> > 
> > > If I do "xm save dom file", followed by "xm
restore file;
> xm restore
> > > file", I get two domains with the same name. Surely, 
> that''s not quite
> > > right? [Particularly since they both will be using the 
> same disk-image,
> > > etc]. 
> > 
> > You shouldn''t do that. ;-)
> > 
> > The second restore ought to fail when xend (or the hotplug 
> scripts) realise
> > that the block device is already in use.
> 
> The second restore ought to fail before it gets anywhere near hotplug
> scripts. XenD should be enforcing name & UUID uniqueness when creating
> guest VMs.  Even ''xm create'' lets you start the same
guest twice
> 
> http://lists.xensource.com/archives/html/xen-devel/2007-04/msg
> 00279.html
Do you have any info to bracket back when this was still working? I
don''t even really know (for sure) which file(s) to look at [of course,
it''s limited to a few files, but all have quote a few changes lately],
since I don''t know where this functionality used to be (or where
it''s
supposed to go). I''ll keep looking, but having a "time-limit"
for it
working correctly would reduce the number of changesets. The data of
your test is roughly 14800, so it has to be broken before that
changeset.

--
Mats
> 
> Dan.
> -- 
> |=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 
> 978 392 2496 -=|
> |=-           Perl modules: http://search.cpan.org/~danberr/  
>             -=|
> |=-               Projects: http://freshmeat.net/~danielpb/   
>             -=|
> |=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF 
> F742 7D3B 9505  -=| 
> 
> 
> 


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> -----Original Message-----
> From: xen-devel-bounces@lists.xensource.com 
> [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of 
> Petersson, Mats
> Sent: 22 May 2007 12:16
> To: Daniel P. Berrange; Keir Fraser
> Cc: xen-devel
> Subject: RE: [Xen-devel] Should "xm restore" be able to 
> create two domains with the same name?
> 
>  
> 
> > -----Original Message-----
> > From: Daniel P. Berrange [mailto:berrange@redhat.com] 
> > Sent: 18 May 2007 15:08
> > To: Keir Fraser
> > Cc: Petersson, Mats; xen-devel
> > Subject: Re: [Xen-devel] Should "xm restore" be able to 
> > create two domains with the same name?
> > 
> > On Fri, May 18, 2007 at 02:55:22PM +0100, Keir Fraser wrote:
> > > 
> > > 
> > > 
> > > On 18/5/07 14:49, "Petersson, Mats" 
> <Mats.Petersson@amd.com> wrote:
> > > 
> > > > If I do "xm save dom file", followed by "xm
restore file;
> > xm restore
> > > > file", I get two domains with the same name. Surely, 
> > that''s not quite
> > > > right? [Particularly since they both will be using the 
> > same disk-image,
> > > > etc]. 
> > > 
> > > You shouldn''t do that. ;-)
> > > 
> > > The second restore ought to fail when xend (or the hotplug 
> > scripts) realise
> > > that the block device is already in use.
> > 
> > The second restore ought to fail before it gets anywhere 
> near hotplug
> > scripts. XenD should be enforcing name & UUID uniqueness 
> when creating
> > guest VMs.  Even ''xm create'' lets you start the same
guest twice
> > 
> > http://lists.xensource.com/archives/html/xen-devel/2007-04/msg
> > 00279.html
> 
> Do you have any info to bracket back when this was still working? I
> don''t even really know (for sure) which file(s) to look at [of
course,
> it''s limited to a few files, but all have quote a few changes
lately],
> since I don''t know where this functionality used to be (or where
it''s
> supposed to go). I''ll keep looking, but having a
"time-limit" for it
> working correctly would reduce the number of changesets. The data of
> your test is roughly 14800, so it has to be broken before that
> changeset.
Interestingly, I found that "xm-test" has a test
".../tests/create/04_create_conflictname_neg.py", which supposedly
test
this behaviour. It seems unchanged for quite some time - so presumably
this test is now "failing". 

--
Mats
> 
> --
> Mats
> > 
> > Dan.
> > -- 
> > |=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 
> > 978 392 2496 -=|
> > |=-           Perl modules: http://search.cpan.org/~danberr/  
> >             -=|
> > |=-               Projects: http://freshmeat.net/~danielpb/   
> >             -=|
> > |=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF 
> > F742 7D3B 9505  -=| 
> > 
> > 
> > 
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
> 
> 
> 


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> -----Original Message-----
> From: Petersson, Mats 
> Sent: 22 May 2007 13:03
> To: Petersson, Mats; Daniel P. Berrange; Keir Fraser
> Cc: xen-devel
> Subject: RE: [Xen-devel] Should "xm restore" be able to 
> create two domains with the same name?
> 
> > -----Original Message-----
> > From: xen-devel-bounces@lists.xensource.com 
> > [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of 
> > Petersson, Mats
> > Sent: 22 May 2007 12:16
> > To: Daniel P. Berrange; Keir Fraser
> > Cc: xen-devel
> > Subject: RE: [Xen-devel] Should "xm restore" be able to 
> > create two domains with the same name?
> > 
> >  
> > 
> > > -----Original Message-----
> > > From: Daniel P. Berrange [mailto:berrange@redhat.com] 
> > > Sent: 18 May 2007 15:08
> > > To: Keir Fraser
> > > Cc: Petersson, Mats; xen-devel
> > > Subject: Re: [Xen-devel] Should "xm restore" be able to
> > > create two domains with the same name?
> > > 
> > > On Fri, May 18, 2007 at 02:55:22PM +0100, Keir Fraser wrote:
> > > > 
> > > > 
> > > > 
> > > > On 18/5/07 14:49, "Petersson, Mats" 
> > <Mats.Petersson@amd.com> wrote:
> > > > 
> > > > > If I do "xm save dom file", followed by
"xm restore file;
> > > xm restore
> > > > > file", I get two domains with the same name.
Surely,
> > > that''s not quite
> > > > > right? [Particularly since they both will be using the 
> > > same disk-image,
> > > > > etc]. 
> > > > 
> > > > You shouldn''t do that. ;-)
> > > > 
> > > > The second restore ought to fail when xend (or the hotplug 
> > > scripts) realise
> > > > that the block device is already in use.
> > > 
> > > The second restore ought to fail before it gets anywhere 
> > near hotplug
> > > scripts. XenD should be enforcing name & UUID uniqueness 
> > when creating
> > > guest VMs.  Even ''xm create'' lets you start the
same guest twice
> > > 
> > > http://lists.xensource.com/archives/html/xen-devel/2007-04/msg
> > > 00279.html
> > 
> > Do you have any info to bracket back when this was still working? I
> > don''t even really know (for sure) which file(s) to look at 
> [of course,
> > it''s limited to a few files, but all have quote a few 
> changes lately],
> > since I don''t know where this functionality used to be (or 
> where it''s
> > supposed to go). I''ll keep looking, but having a
"time-limit" for it
> > working correctly would reduce the number of changesets. The data of
> > your test is roughly 14800, so it has to be broken before that
> > changeset.
> 
> Interestingly, I found that "xm-test" has a test 
> ".../tests/create/04_create_conflictname_neg.py", which 
> supposedly test this behaviour. It seems unchanged for quite 
> some time - so presumably this test is now "failing". 
I think I''ve found the place in XendDomainInfo.py and the fix...
Testing
it right now. 

--
Mats
> 
> --
> Mats
> > 
> > --
> > Mats
> > > 
> > > Dan.
> > > -- 
> > > |=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 
> > > 978 392 2496 -=|
> > > |=-           Perl modules: http://search.cpan.org/~danberr/  
> > >             -=|
> > > |=-               Projects: http://freshmeat.net/~danielpb/   
> > >             -=|
> > > |=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF 
> > > F742 7D3B 9505  -=| 
> > > 
> > > 
> > > 
> > 
> > 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> > 
> > 
> > 


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