zfs discuss - Sep 2006 - Importing ZFS filesystems across architectures...

OK, this may seem like a stupid question (and we all know that there are
such things...)

I''m considering sharing a disk array (something like a 3510FC) between
two different systems, a SPARC and an Opteron.

Will ZFS transparently work to import/export pools between the two
systems?  That is, can I export a pool created on the SPARC box, then
import that on the Opteron box and have all the data there (and the pool
work normally)?

Normally, I''d run into problems with Fdisk vs EFI vs VTOC
labeling/partitioning, but I was hoping that ZFS would magically make my
life simpler here...

:-)




-- 
Erik Trimble
Java System Support
Mailstop:  usca14-102
Phone:  x17195
Santa Clara, CA
Timezone: US/Pacific (GMT-0800)

If you''re using EFI labels, yes (VTOC labels are not endian neutral).
ZFS will automatically convert endianness from the on-disk format, and
new data will be written using the native endianness, so data will be
gradually be rewritten to avoid the byteswap overhead.

- Eric

On Wed, Sep 13, 2006 at 03:55:27PM -0700, Erik Trimble
wrote:
> OK, this may seem like a stupid question (and we all know that there are
> such things...)
> 
> I''m considering sharing a disk array (something like a 3510FC)
between
> two different systems, a SPARC and an Opteron.
> 
> Will ZFS transparently work to import/export pools between the two
> systems?  That is, can I export a pool created on the SPARC box, then
> import that on the Opteron box and have all the data there (and the pool
> work normally)?
> 
> Normally, I''d run into problems with Fdisk vs EFI vs VTOC
> labeling/partitioning, but I was hoping that ZFS would magically make my
> life simpler here...
> 
> :-)
> 
> 
> 
> 
> -- 
> Erik Trimble
> Java System Support
> Mailstop:  usca14-102
> Phone:  x17195
> Santa Clara, CA
> Timezone: US/Pacific (GMT-0800)
> 
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock

Erik Trimble wrote:
> OK, this may seem like a stupid question (and we all know that there are
> such things...)
>
> I''m considering sharing a disk array (something like a 3510FC)
between
> two different systems, a SPARC and an Opteron.
>
> Will ZFS transparently work to import/export pools between the two
> systems?  That is, can I export a pool created on the SPARC box, then
> import that on the Opteron box and have all the data there (and the pool
> work normally)?
>
> Normally, I''d run into problems with Fdisk vs EFI vs VTOC
> labeling/partitioning, but I was hoping that ZFS would magically make my
> life simpler here...
>
>   
As long as you don''t try to mount the pool from both systems at the
same
time, do funky auto-takeover stuff, etc. you should be good to go....at 
least you''re supposed to be able to do this. I haven''t tested
it.

Erik Trimble wrote:
> OK, this may seem like a stupid question (and we all know that there are
> such things...)
> 
> I''m considering sharing a disk array (something like a 3510FC)
between
> two different systems, a SPARC and an Opteron.
> 
> Will ZFS transparently work to import/export pools between the two
> systems?  That is, can I export a pool created on the SPARC box, then
> import that on the Opteron box and have all the data there (and the pool
> work normally)?
> 
> Normally, I''d run into problems with Fdisk vs EFI vs VTOC
> labeling/partitioning, but I was hoping that ZFS would magically make my
> life simpler here...

Use EFI and you should be fine..... as long as you don''t try to
import any pools on both hosts at the same time.



James

On 9/13/06, Erik Trimble <Erik.Trimble at sun.com>
wrote:
> OK, this may seem like a stupid question (and we all know that there are
> such things...)
>
> I''m considering sharing a disk array (something like a 3510FC)
between
> two different systems, a SPARC and an Opteron.
>
> Will ZFS transparently work to import/export pools between the two
> systems?  That is, can I export a pool created on the SPARC box, then
> import that on the Opteron box and have all the data there (and the pool
> work normally)?
>
yes, this is a design feature.

When you first move the pool and import it. The system will read the
blocks of  data and see that its a different endian that the current
host, and convert as necessary, as data is written, its is written in
native format, so data that is written by the pools new host will
suffer no endian penalty reading data it wrote, and a small penalty
accessing data from the old endian type.

James Dickens
uadmin.blogspot.com

> Normally, I''d run into problems with Fdisk vs EFI vs VTOC
> labeling/partitioning, but I was hoping that ZFS would magically make my
> life simpler here...
>
> :-)
>
>
>
>
> --
> Erik Trimble
> Java System Support
> Mailstop:  usca14-102
> Phone:  x17195
> Santa Clara, CA
> Timezone: US/Pacific (GMT-0800)
>
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

Eric Schrock wrote:
> If you''re using EFI labels, yes (VTOC labels are not endian
neutral).
> ZFS will automatically convert endianness from the on-disk format, and
> new data will be written using the native endianness, so data will be
> gradually be rewritten to avoid the byteswap overhead.
> 
now, when you say "data", you just mean "metadata", right?

On Thu, Sep 21, 2006 at 07:28:20PM -0700, Philip Brown
wrote:
> Eric Schrock wrote:
> >If you''re using EFI labels, yes (VTOC labels are not endian
neutral).
> >ZFS will automatically convert endianness from the on-disk format, and
> >new data will be written using the native endianness, so data will be
> >gradually be rewritten to avoid the byteswap overhead.
> >
> 
> now, when you say "data", you just mean "metadata",
right?
Of course - thanks for pointing that out.  Though it would be an
exciting feature of PsychicFS to automatically translate your
application data ;-)

- Eric

--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock

Philip Brown wrote On 09/21/06 20:28,:
> Eric Schrock wrote:
> 
>> If you''re using EFI labels, yes (VTOC labels are not endian
neutral).
>> ZFS will automatically convert endianness from the on-disk format, and
>> new data will be written using the native endianness, so data will be
>> gradually be rewritten to avoid the byteswap overhead.
>>
> 
> now, when you say "data", you just mean "metadata",
right?
Yes. ZFS has no knowledge of the layout of any structured records
written by applications, so it can''t byteswap user data.

Neil