ZFS problems

Xin Li delphij at delphij.net
Thu Feb 28 01:09:04 UTC 2013


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On 02/27/13 16:44, Glen Barber wrote:
> On Wed, Feb 27, 2013 at 04:37:47PM -0800, Xin Li wrote:
>>> In mid-February, zpool version was upgraded to include 
>>> lz4_compress.  My understanding was that changing from the 
>>> OpenSolaris ZFS version number scheme (i.e., "v28") to what we
>>> have on -CURRENT (i.e., "5000") was so that we can track
>>> crossing the point of no return with pool version upgrades.
>>> 
>>> On my system, vfs.zfs.version.spa has been at 5000 since this 
>>> original change.
>>> 
>>> Is my understanding incorrect?  Or should vfs.zfs.version.spa
>>> be incremented with major, non-backwards-compatible changes?
>> 
>> That's incorrect.  In theory vfs.zfs.version.spa will never ever 
>> change in the future, and all new features will be denoted by
>> feature flags, which is an extensible way of representing
>> features and whether they are compatible with the running
>> system.
>> 
> 
> Thank you for clarifying.
> 
> As there does not seem to be a specific sysctl that we can look
> for, I am inclined to say there should be UPDATING entries for such
> changes to note (at least for now) that 'make -C /usr/src/cddl
> install' can help prevent foot shooting.

Grrr I should have noticed this when doing code review for the change.
 No, this is not intentional and has to be fixed, the issue was
introduced in r247265 ("deadman" feature).

Martin actually have done very good job maintaining ioctl
compatibility when we jumped from v15 to v28 that most people didn't
even notice that the ioctl was changed.

Cheers,
- -- 
Xin LI <delphij at delphij.net>    https://www.delphij.net/
FreeBSD - The Power to Serve!           Live free or die
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