[Gluster-users] Proposal to mark few features as Deprecated / SunSet from Version 5.0

Amar Tumballi atumball at redhat.com
Thu Jul 19 06:56:35 UTC 2018

*Hi all,Over last 12 years of Gluster, we have developed many features, and
continue to support most of it till now. But along the way, we have figured
out better methods of doing things. Also we are not actively maintaining
some of these features.We are now thinking of cleaning up some of these
‘unsupported’ features, and mark them as ‘SunSet’ (i.e., would be totally
taken out of codebase in following releases) in next upcoming release,
v5.0. The release notes will provide options for smoothly migrating to the
supported configurations.If you are using any of these features, do let us
know, so that we can help you with ‘migration’.. Also, we are happy to
guide new developers to work on those components which are not actively
being maintained by current set of developers.List of features hitting
sunset:‘cluster/stripe’ translator:This translator was developed very early
in the evolution of GlusterFS, and addressed one of the very common
question of Distributed FS, which is “What happens if one of my file is
bigger than the available brick. Say, I have 2 TB hard drive, exported in
glusterfs, my file is 3 TB”. While it solved the purpose, it was very hard
to handle failure scenarios, and give a real good experience to our users
with this feature. Over the time, Gluster solved the problem with it’s
‘Shard’ feature, which solves the problem in much better way, and provides
much better solution with existing well supported stack. Hence the proposal
for Deprecation.If you are using this feature, then do write to us, as it
needs a proper migration from existing volume to a new full supported
volume type before you upgrade.‘storage/bd’ translator:This feature got
into the code base 5 years back with this patch
<http://review.gluster.org/4809>[1]. Plan was to use a block device
directly as a brick, which would help to handle disk-image storage much
easily in glusterfs.As the feature is not getting more contribution, and we
are not seeing any user traction on this, would like to propose for
Deprecation.If you are using the feature, plan to move to a supported
gluster volume configuration, and have your setup ‘supported’ before
upgrading to your new gluster version.‘RDMA’ transport support:Gluster
started supporting RDMA while ib-verbs was still new, and very high-end
infra around that time were using Infiniband. Engineers did work with
Mellanox, and got the technology into GlusterFS for better data migration,
data copy. While current day kernels support very good speed with IPoIB
module itself, and there are no more bandwidth for experts in these area to
maintain the feature, we recommend migrating over to TCP (IP based) network
for your volume.If you are successfully using RDMA transport, do get in
touch with us to prioritize the migration plan for your volume. Plan is to
work on this after the release, so by version 6.0, we will have a cleaner
transport code, which just needs to support one type.‘Tiering’
featureGluster’s tiering feature which was planned to be providing an
option to keep your ‘hot’ data in different location than your cold data,
so one can get better performance. While we saw some users for the feature,
it needs much more attention to be completely bug free. At the time, we are
not having any active maintainers for the feature, and hence suggesting to
take it out of the ‘supported’ tag.If you are willing to take it up, and
maintain it, do let us know, and we are happy to assist you.If you are
already using tiering feature, before upgrading, make sure to do gluster
volume tier detach all the bricks before upgrading to next release. Also,
we recommend you to use features like dmcache on your LVM setup to get best
performance from bricks.‘Quota’This is a call out for ‘Quota’ feature, to
let you all know that it will be ‘no new development’ state. While this
feature is ‘actively’ in use by many people, the challenges we have in
accounting mechanisms involved, has made it hard to achieve good
performance with the feature. Also, the amount of extended attribute
get/set operations while using the feature is not very ideal. Hence we
recommend our users to move towards setting quota on backend bricks
directly (ie, XFS project quota), or to use different volumes for different
directories etc.As the feature wouldn’t be deprecated immediately, the
feature doesn’t need a migration plan when you upgrade to newer version,
but if you are a new user, we wouldn’t recommend setting quota feature. By
the release dates, we will be publishing our best alternatives guide for
gluster’s current quota feature.Note that if you want to contribute to the
feature, we have project quota based issue open
<https://github.com/gluster/glusterfs/issues/184>[2] Happy to get
contributions, and help in getting a newer approach to
Quota.------------------------------These are our set of initial features
which we propose to take out of ‘fully’ supported features. While we are in
the process of making the user/developer experience of the project much
better with providing well maintained codebase, we may come up with few
more set of features which we may possibly consider to move out of support,
and hence keep watching this space.[1] - http://review.gluster.org/4809
<http://review.gluster.org/4809>[2] -
<https://github.com/gluster/glusterfs/issues/184>Regards,Vijay, Shyam, Amar*
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