[libvirt] [PATCH] manual: Add virsh manual about specified migration host

[Yasunori Goto]

Chen-san,

> ping...

I suppose it seems to be difficult for users to understand...
I think following order of description is desirable.

 - What is migrateuri?
 - What is benefit?
 - If it is ommited, what is happen?
      The case of "migration_host" is specified.
      The case of nothing specified

How is the following example? I hope it is good hint for you.
(I'm newbie of man page of virsh, and may be I misunderstand migrateuri/migration_host.
 So please check and correct it.)

---
diff --git a/tools/virsh.pod b/tools/virsh.pod
index 02671b4..0ce0ca4 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -1236,9 +1236,8 @@ seen from the source machine.

 =back

-When I<migrateuri> is not specified, libvirt will automatically determine the
-hypervisor specific URI, by looking up the target host's configured hostname.
-There are a few scenarios where specifying I<migrateuri> may help:
+I<migrateuri> is specifed for which IP/URL is used for transfer migration data.
+Specifying I<migrateuri> may be helpful on some scenarios.

 =over 4

@@ -1262,6 +1261,15 @@ order to comply with local firewall policies.

 =back

+When I<migrateuri> is not specified, libvirt will ask destination side whether
+"migration_host" is specified or not in qemu.conf at first. If "migration_host"
+is specified in qemu.conf, libvirt will use its network for transfer migration data.
+("migration_host" is useful when hosts has multiple network interface.)
+
+If "migration_host" is not specified too, then libvirt will automatically
+determine the hypervisor specific URI, by looking up the target host's
+configured hostname.
+
 Optional I<graphicsuri> overrides connection parameters used for automatically
 reconnecting a graphical clients at the end of migration. If omitted, libvirt
 will compute the parameters based on target host IP address. In case the
--

Thanks,

> 
> On Fri, 2014-05-30 at 14:54 +0800, Chen Fan wrote: 
> > the 'migration_host' description maybe have a bit of difficulty to
> > understand for user, so add this manual for them.
> > 
> > Signed-off-by: Chen Fan <chen.fan.fnst at cn.fujitsu.com>
> > ---
> >  tools/virsh.pod | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/virsh.pod b/tools/virsh.pod
> > index de9a4f7..8d77a2f 100644
> > --- a/tools/virsh.pod
> > +++ b/tools/virsh.pod
> > @@ -1238,6 +1238,11 @@ seen from the source machine.
> >  
> >  When I<migrateuri> is not specified, libvirt will automatically determine the
> >  hypervisor specific URI, by looking up the target host's configured hostname.
> > +In particular, some hypervisors support having this migration hostname specified
> > +separately by setting 'migration_host' in definition file, if 'migration_host'
> > +is specified, the hostname or IP address will be used to as the default I<migrateuri>
> > +while running migration from source host. if 'migration_host' is not specified,
> > +the migration hostname is set to the host's configured hostname by default.
> >  There are a few scenarios where specifying I<migrateuri> may help:
> >  
> >  =over 4
> > @@ -1251,7 +1256,9 @@ explicitly specified, using an IP address, or a correct hostname.
> >  interfaces, it might be desirable for the migration data stream to be sent over
> >  a specific interface for either security or performance reasons.  In this case
> >  I<migrateuri> should be explicitly specified, using an IP address associated
> > -with the network to be used.
> > +with the network to be used. In particular, Some hypervisors could be easy to
> > +specify the default network interface by setting 'migration_host'. then the
> > +I<migrateuri> can be omitted.
> >  
> >  =item * The firewall restricts what ports are available.  When libvirt generates
> >  a migration URI, it will pick a port number using hypervisor specific rules.
> 

-- 
Yasunori Goto <y-goto at jp.fujitsu.com>