zfs discuss - Jan 2007 - Eliminating double path with ZFS''s volume manager

Hi,


Since they have installed a second path to our Hitachi SAN, my Mac OS X Server
4.8 mounts every SAN disk twice.
I asked everywhere, if there''s a way, to correct that. And the only
answer so far was, that I need a volume manager, that can be configured to
consider two volumes as being identical.
Now that Mac OS X Leopard supports ZFS, could using ZFS be the solution for this
problem? If yes, how could I achieve this?


Thanks for your help!
Phil
 
 
This message posted from opensolaris.org

Hello Philip,

Monday, January 15, 2007, 10:44:49 AM, you wrote:

PM> Hi,


PM> Since they have installed a second path to our Hitachi SAN, my
PM> Mac OS X Server 4.8 mounts every SAN disk twice.
PM> I asked everywhere, if there''s a way, to correct that. And the
PM> only answer so far was, that I need a volume manager, that can be
PM> configured to consider two volumes as being identical.
PM> Now that Mac OS X Leopard supports ZFS, could using ZFS be the
PM> solution for this problem? If yes, how could I achieve this?


1. I don''t know what kind of file system you already have on those
disks but if you really mounted them twice you could have already
corrupt those file systems

2. I belive it''s definitely possible to just correct your config under
Mac OS without any need to use other fs or volume manager, however
going to zfs could be a good idea anyway

3. if you put those disks under ZFS it should just work despite of
having second path

-- 
Best regards,
 Robert                            mailto:rmilkowski at task.gda.pl
                                       http://milek.blogspot.com

Hi,

> Monday, January 15, 2007, 10:44:49 AM, you wrote:
> PM> Since they have installed a second path to our Hitachi SAN, my
> PM> Mac OS X Server 4.8 mounts every SAN disk twice.
> PM> I asked everywhere, if there''s a way, to correct that. And
the
> PM> only answer so far was, that I need a volume manager, that can be
> PM> configured to consider two volumes as being identical.
> PM> Now that Mac OS X Leopard supports ZFS, could using ZFS be the
> PM> solution for this problem? If yes, how could I achieve this?
> 
> 1. I don''t know what kind of file system you already
> have on those
> disks but if you really mounted them twice you could
> have already
> corrupt those file systems
I have now de-connected one cable.	:-8

> 2. I believe it''s definitely possible to just correct
> your config under
> Mac OS without any need to use other fs or volume
> manager,
Apart from the proposition about using a special type of switch, I would be very
interested in any information you have. So far not our SAN expert, nor our Mac
expert, nor the very expensive Apple Server support we have, could help us.

> however
> going to zfs could be a good idea anyway
I think so too. I just have to wait until Leopard.

> 3. if you put those disks under ZFS it should just
> work despite of
> having second path
So you would propose, to just add one of

	/dev/disk4s10
	/dev/disk5s10

into the ZFS pool?
Is there no way, to explain ZFS, that both of these disks are identical
(probably not clones), so that one could profit from the path redundancy?


Thanks
Phil
 
 
This message posted from opensolaris.org

Go poke around in the multipath Xsan storage pool properties. Specifies how
Xsan uses multiple Fibre Channel paths between clients and storage. This is
the equiv of Veritas DMP or [whatever we now call] Solaris MPxIO
/d


2007/1/15, Philip M?tteli <Philip.Moetteli at
econophone.ch>:
>
> Hi,
>
>
> > Monday, January 15, 2007, 10:44:49 AM, you wrote:
> > PM> Since they have installed a second path to our Hitachi SAN, my
> > PM> Mac OS X Server 4.8 mounts every SAN disk twice.
> > PM> I asked everywhere, if there''s a way, to correct that.
And the
> > PM> only answer so far was, that I need a volume manager, that can
be
> > PM> configured to consider two volumes as being identical.
> > PM> Now that Mac OS X Leopard supports ZFS, could using ZFS be the
> > PM> solution for this problem? If yes, how could I achieve this?
> >
> > 1. I don''t know what kind of file system you already
> > have on those
> > disks but if you really mounted them twice you could
> > have already
> > corrupt those file systems
>
> I have now de-connected one cable.      :-8
>
>
> > 2. I believe it''s definitely possible to just correct
> > your config under
> > Mac OS without any need to use other fs or volume
> > manager,
>
> Apart from the proposition about using a special type of switch, I would
> be very interested in any information you have. So far not our SAN expert,
> nor our Mac expert, nor the very expensive Apple Server support we have,
> could help us.
>
>
> > however
> > going to zfs could be a good idea anyway
>
> I think so too. I just have to wait until Leopard.
>
>
> > 3. if you put those disks under ZFS it should just
> > work despite of
> > having second path
>
> So you would propose, to just add one of
>
>         /dev/disk4s10
>         /dev/disk5s10
>
> into the ZFS pool?
> Is there no way, to explain ZFS, that both of these disks are identical
> (probably not clones), so that one could profit from the path redundancy?
>
>
> Thanks
> Phil
>
>
> This message posted from opensolaris.org
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>


-- 
Dominic Kay
+44 780 124 6099
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Robert Milkowski wrote:
>
> 2. I belive it''s definitely possible to just correct your config
under
> Mac OS without any need to use other fs or volume manager, however
> going to zfs could be a good idea anyway

That implies that MacOS has some sort of native SCSI multipathing like 
Solaris Mpxio. Does such a beast exist?

Hi Torrey,

I think it does if you buy Xsan. Its still a separate product isn''t
it? Thought its more like QFS + MPXIO.

Best Regards,
Jason

On 1/15/07, Torrey McMahon <tmcmahon2 at yahoo.com>
wrote:
> Robert Milkowski wrote:
> >
> > 2. I belive it''s definitely possible to just correct your
config under
> > Mac OS without any need to use other fs or volume manager, however
> > going to zfs could be a good idea anyway
>
>
> That implies that MacOS has some sort of native SCSI multipathing like
> Solaris Mpxio. Does such a beast exist?
>
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

Got me. However, transport multipathing - Like Mpxio, DLM, VxDMP, etc. - 
is usually separated from the filesystem layers.

Jason J. W. Williams wrote:
> Hi Torrey,
>
> I think it does if you buy Xsan. Its still a separate product
isn''t
> it? Thought its more like QFS + MPXIO.
>
> Best Regards,
> Jason
>
> On 1/15/07, Torrey McMahon <tmcmahon2 at yahoo.com> wrote:
>> Robert Milkowski wrote:
>> >
>> > 2. I belive it''s definitely possible to just correct your
config under
>> > Mac OS without any need to use other fs or volume manager, however
>> > going to zfs could be a good idea anyway
>>
>>
>> That implies that MacOS has some sort of native SCSI multipathing like
>> Solaris Mpxio. Does such a beast exist?
>>
>> _______________________________________________
>> zfs-discuss mailing list
>> zfs-discuss at opensolaris.org
>> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>>
>

Hi Torrey,

Looks like its got a half-way decent multipath design:
http://docs.info.apple.com/article.html?path=Xsan/1.1/en/c3xs12.html

Whether or not it works is another story I suppose. ;-)

Best Regards,
Jason

On 1/15/07, Torrey McMahon <tmcmahon2 at yahoo.com>
wrote:
> Got me. However, transport multipathing - Like Mpxio, DLM, VxDMP, etc. -
> is usually separated from the filesystem layers.
>
> Jason J. W. Williams wrote:
> > Hi Torrey,
> >
> > I think it does if you buy Xsan. Its still a separate product
isn''t
> > it? Thought its more like QFS + MPXIO.
> >
> > Best Regards,
> > Jason
> >
> > On 1/15/07, Torrey McMahon <tmcmahon2 at yahoo.com> wrote:
> >> Robert Milkowski wrote:
> >> >
> >> > 2. I belive it''s definitely possible to just correct
your config under
> >> > Mac OS without any need to use other fs or volume manager,
however
> >> > going to zfs could be a good idea anyway
> >>
> >>
> >> That implies that MacOS has some sort of native SCSI multipathing
like
> >> Solaris Mpxio. Does such a beast exist?
> >>
> >> _______________________________________________
> >> zfs-discuss mailing list
> >> zfs-discuss at opensolaris.org
> >> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
> >>
> >
>
>
>

> Go poke around in the multipath Xsan storage pool
> properties. Specifies
> how Xsan uses multiple Fibre Channel paths between
> clients and storage.
> This is the equiv of Veritas DMP or [whatever we now
> call] Solaris MPxIO
You mean, I should find some configuration file? Well, I can''t find
one. Nothing like ''scsi_vhci.conf''.
 
 
This message posted from opensolaris.org

> Robert Milkowski wrote:
> >
> > 2. I belive it''s definitely possible to just
> correct your config under
> > Mac OS without any need to use other fs or volume
> manager, however
> > going to zfs could be a good idea anyway
> 
> 
> That implies that MacOS has some sort of native SCSI
> multipathing like 
> Solaris Mpxio. Does such a beast exist?
That''s exactly the question. I''m not aware of any. The only
such thing, could be in Xsan. But we don''t have Xsan here; we have
Hitachi. And this tool called ''Xsan Admin'' is not freely
available and the person at the Apple Support said, it wouldn''t help in
my case.
 
 
This message posted from opensolaris.org

> Looks like its got a half-way decent multipath
> design:
> http://docs.info.apple.com/article.html?path=Xsan/1.1/
> en/c3xs12.html
Great, but that is with Xsan. If I don''t exchange our Hitachi with an
Xsan, I don''t have this ''cvadmin''.
 
 
This message posted from opensolaris.org

Hi Philip,

I''m not an expert, so I''m afraid I don''t know what to
tell you. I''d
call Apple Support and see what they say. As horrid as they are at
Enterprise support they may be the best ones to clarify if
multipathing is available without Xsan.


Best Regards,
Jason

On 1/16/07, Philip M?tteli <Philip.Moetteli at econophone.ch>
wrote:
> > Looks like its got a half-way decent multipath
> > design:
> > http://docs.info.apple.com/article.html?path=Xsan/1.1/
> > en/c3xs12.html
>
> Great, but that is with Xsan. If I don''t exchange our Hitachi with
an Xsan, I don''t have this ''cvadmin''.
>
>
> This message posted from opensolaris.org
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>