On Thu, Dec 6, 2018, at 11:40 AM, Matthew Ahrens wrote:
>
>
> On Wed, Dec 5, 2018 at 9:21 PM Josh Paetzel <[email protected]> wrote:
>> There was a proposal on this mailing list a week or so ago that
>> sparked some good discussion regarding setting feature flags at pool
>> creation. We discussed this proposal on the last OpenZFS call and
>> while we all agreed it was a good idea, we felt the UI could use a
>> little workshopping.>
> Thanks for leading this discussion, Josh!
>
>>
>> This proposal is simply a starting point for a discussion.
>>
>> The proposal is to add an optional flag at zpool create time. -o
>> features=>>
>> which can be set to one of the following 4 settings:
>>
>> all: The default and the current behavior of zpool create. This
>> setting enables all features supported by the in use OpenZFS
>> version.>>
>> compat: Enable async_destroy, empty_bpobj, filesystem_limits,
>> lz4_compress, spacemap_histogram, extensible_dataset, bookmarks,
>> enabled_txg, and hole_birth. This set of features is supported by
>> FreeBSD/FreeNAS 9.3 (July of 2014), ZoL 0.6.4 ( 0.6.5.6 was used in
>> Ubuntu 16.04 LTS), and Illumos in the early to mid 2014 era.>
> I think the term "portable" is more specific than "compat[ible]", so
> "-o features=portable" is probably a better name. Thanks to whoever
> suggested that at the meeting Tuesday.
+1
> I think that the definition of "-o features=portable" needs to change
> over time, as features become more widely available. Do you have
> thoughts on how specifically we should do that?
One thought would be: As a delivery vehicle drops out of support we can
remove it from the list. So say we have -o features=portable include
Ubuntu 16.04 LTS. When support for Ubuntu 16.04 LTS expires we remove
it from the portable list. Now, that directly contradicts the first
pass at this. For instance FreeBSD (and FreeNAS) 9.3-R have long been
out of support by the "vendor"
Another thought would be "do it by date" . Which is to say, "Here are
the Tier 1 platforms. By using the portable flag you get feature flags
that any Tier 1 platform supported 3 years ago from when what you are
using now was released."
Both of those are not very good ways to express, "systems that people
might reasonably be using and might want to migrate pools between"
--
Thanks,
Josh Paetzel
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