Zevo -> FreeBSD

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Re: Zevo -> FreeBSD

Post by ghaskins » Wed Jun 12, 2013 10:16 am

ilovezfs wrote:ZEVO and FreeBSD 9 both use pool version 28. ZFS on Linux uses pool version 5000.


FWIW, you can "downgrade" a zpool's version at creation to some least-common-denominator. (For instance, I created a zpool on OmniOS as v28 even through it supports v5000, specifically to retain compatibility with other platforms). I would guess ZoL supports this notion too.
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Re: Zevo -> FreeBSD

Post by ilovezfs » Wed Jun 12, 2013 10:19 am

monkeyfoahead wrote:right I looked this up. I was just afraid their would be implementation differences that my bite me in the rear.

Also, FreeBSD 10 uses pool version 5000, so you would need to manually set pool version 28 to maintain compatibility if you were creating the pool on FreeBSD 10. And by "not upgrading" he meant not upgrading from 28 to 5000, if you use use ZFS on Linux, Free BSD 10, or one of the Illumos based OSs (e.g., OpenIndiana). Once you import a zpool on an OS that supports a higher pool version, you can upgrade it in place. But then it can't be downgraded.

As for your rear, I wouldn't expect xattr to work interchangeably, for example.
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Re: Zevo -> FreeBSD

Post by monkeyfoahead » Wed Jun 12, 2013 10:58 am

ilovezfs wrote:
monkeyfoahead wrote:right I looked this up. I was just afraid their would be implementation differences that my bite me in the rear.

Also, FreeBSD 10 uses pool version 5000, so you would need to manually set pool version 28 to maintain compatibility if you were creating the pool on FreeBSD 10. And by "not upgrading" he meant not upgrading from 28 to 5000, if you use use ZFS on Linux, Free BSD 10, or one of the Illumos based OSs (e.g., OpenIndiana). Once you import a zpool on an OS that supports a higher pool version, you can upgrade it in place. But then it can't be downgraded.

As for your rear, I wouldn't expect xattr to work interchangeably, for example.


Ahh I see, well I use 9.1 Release and the zpool version on there is 28. So hopefully I can avoid the upgrade fiasco. Also, I don't give a sh*t about xattr, so maybe I'm safe there as well.


As a side note, why the hell is there a 5000 version number?
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Re: Zevo -> FreeBSD

Post by ghaskins » Wed Jun 12, 2013 11:05 am

monkeyfoahead wrote:As a side note, why the hell is there a 5000 version number?


This is my own inference, so don't quote me on it: But my impression is that the ZFS FOSS community wanted to add their own features to ZFS post v28, and didn't want to conflict with the upstream Solaris namespace (e.g. v29, v30, etc). Therefore, they picked a version number that is reasonably disparate as to avoid any collisions with anything Sun/Oracle does in the future. Mostly it just looks awkward to jump v28->v5000. It would only be a problem if the Solaris guys ever start using v5000 as well.

Kind Regards,
-Greg
Last edited by ghaskins on Wed Jun 12, 2013 12:24 pm, edited 1 time in total.
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Re: Zevo -> FreeBSD

Post by ilovezfs » Wed Jun 12, 2013 11:11 am

monkeyfoahead wrote:Ahh I see, well I use 9.1 Release and the zpool version on there is 28. So hopefully I can avoid the upgrade fiasco. Also, I don't give a sh*t about xattr, so maybe I'm safe there as well.

As a side note, why the hell is there a 5000 version number?

The upgrading fiasco can be avoided by never telling it to upgrade and by never setting a feature flag (which I believe triggers an upgrade). So it should be very easily avoidable.

Pool version 5000 is meant to clearly distinguish the current version of the ZFS fork emanating from the Illumos project from the versions Oracle uses on Oracle Solaris (29-34). The idea is to avoid any accidental collision with Oracle's versioning, which should continue to increment by 1. Pools of version 5000 and greater will not be importable by Oracle Solaris, since they will presumably always be of a "higher" version, unless there is a deliberate attempt to "unfork" the Illumos project if Oracle happens to open source everything at some point. Also, Illumos is leaving open the possibility that they will figure out how to import 29-34, since those have a lower version number.
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Re: Zevo -> FreeBSD

Post by monkeyfoahead » Wed Jun 12, 2013 11:35 am

ilovezfs wrote:
monkeyfoahead wrote:Ahh I see, well I use 9.1 Release and the zpool version on there is 28. So hopefully I can avoid the upgrade fiasco. Also, I don't give a sh*t about xattr, so maybe I'm safe there as well.

As a side note, why the hell is there a 5000 version number?

The upgrading fiasco can be avoided by never telling it to upgrade and by never setting a feature flag (which I believe triggers an upgrade). So it should be very easily avoidable.

Pool version 5000 is meant to clearly distinguish the current version of the ZFS fork emanating from the Illumos project from the versions Oracle uses on Oracle Solaris (29-34). The idea is to avoid any accidental collision with Oracle's versioning, which should continue to increment by 1. Pools of version 5000 and greater will not be importable by Oracle Solaris, since they will presumably always be of a "higher" version, unless there is a deliberate attempt to "unfork" the Illumos project if Oracle happens to open source everything at some point. Also, Illumos is leaving open the possibility that they will figure out how to import 29-34, since those have a lower version number.


Nice, alright thanks for that. What do you think the chances are of a successful import for me? Is damage to the pool likely?
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Re: Zevo -> FreeBSD

Post by ilovezfs » Wed Jun 12, 2013 11:42 am

monkeyfoahead wrote:Nice, alright thanks for that. What do you think the chances are of a successful import for me? Is damage to the pool likely?

I don't think you will have any problems at all.
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Re: Zevo -> FreeBSD

Post by ghaskins » Wed Jun 12, 2013 11:49 am

ilovezfs wrote:I don't think you will have any problems at all.


I second that. The design of ZFS is conducive to cross-platform compatibility. Though to re-iterate, you are advised to find some way to backup first unless you can accept the risk that you might lose the data, even if the risk is small. :)
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Re: Zevo -> FreeBSD

Post by monkeyfoahead » Wed Jun 12, 2013 12:03 pm

ilovezfs wrote:I don't think you will have any problems at all.


ghaskins wrote:
I second that. The design of ZFS is conducive to cross-platform compatibility. Though to re-iterate, you are advised to find some way to backup first unless you can accept the risk that you might lose the data, even if the risk is small. :)


Awesome, thanks alot you guys. The ZEVO community is great! :)
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Cross reference

Post by grahamperrin » Wed Jun 12, 2013 1:34 pm

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