regards
Aravinda
On 03/08/2016 07:32 PM, Pranith Kumar Karampuri wrote:
hi,
Late last week I sent a solution for how to achieve
subdirectory-mount support with access-controls
(http://www.gluster.org/pipermail/gluster-devel/2016-March/048537.html).
What follows here is a short description of how other features of
gluster volumes are implemented for sub-directories.
Please note that the sub-directories are not allowed to be accessed by
normal mounts i.e. top-level volume mounts. All access to the
sub-directories goes only through sub-directory mounts.
1) Geo-replication:
The direction in which we are going is to allow geo-replicating just
some sub-directories and not all of the volume based on options. When
these options are set, server xlators populate extra information in
the frames/xdata to write changelog for the fops coming from their
sub-directory mounts. changelog xlator on seeing this will only
geo-replicate the files/directories that are in the changelog. Thus
only the sub-directories are geo-replicated. There is also a
suggestion from Vijay and Aravinda to have separate domains for
operations inside sub-directories for changelogs.
We can additionally record subdir/client info in Changelog to
differentiate I/O belonging to each subdirs instead of having separate
domains for changelogs.
Just a note, Geo-replication expects target to be Gluster Volume and not
any directory. If subdir 1 to be replicated to remote site A and subdir2
to be replicated to remote site B, then we should have two Geo-rep
session from Master to two remote volumes in remote site A and site B
respectively.(with subdir filter accordingly)
2) Sub-directory snapshots using lvm
Every time a sub-directory needs to be created, Our idea is that the
admin needs to execute subvolume creation command which creates a
mount to an empty snapshot at the given sub-directory name. All these
directories can be modified in parallel and we can take individual
snapshots of each of the directories. We will be providing a detailed
list commands to do the same once they are fleshed out. At the moment
these are the directions we are going to increase granularity from
volume to subdirectory for the main features.
Pranith
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