Re: CephFS usability

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I have been playing with CephFS since before Firefly and I am now
trying to put it into production. You listed a lot of good ideas, but
many of them would seem to help developers and those trying to get the
absolute best performance out of CephFS, more then helping day to day
administration or using CephFS in a typical environment.  The three
things I really need are:

1. Documentation.  The documents for administrating CephFS on the Ceph
site and the man pages are incomplete.  As an example, having to open
a ticket to find the magic options to get ACL support on a FUSE mount
(see ticket #15783) is very inefficient for both the end user and the
Ceph engineers. There are a huge number of mount options between
kernel and FUSE mounts with very little explanation of what they do
and what are the performance costs of using them.  The new CAP
protections are great, if you can figure them out.  Same goes for the
new recovery tools.

2. Snapshots.  Without snapshots I cannot put the file system it into
production in all my use cases.

3. Full support for the SAMBA and Ganesha CephFS modules, including
HA.  Although these modules are not owned by the Ceph team, they need
to be solid to use CephFS at a lot of sites. The GlusterFS team seems
to be doing a lot of work on these interfaces, and it would be nice if
that work was also being done for Ceph.

To make CephFS easier to use in the field, I would really like to see
the base functionality well supported and documented before focusing
on new things. Thank you for everything you are doing.

Eric Eastman

On Thu, Jul 21, 2016 at 6:11 AM, John Spray <jspray@xxxxxxxxxx> wrote:
> Dear list,
>
> I'm collecting ideas for making CephFS easier to use.  This list
> includes some preexisting stuff, as well as some recent ideas from
> people working on the code.  I'm looking for feedback on what's here,
> and any extra ideas people have.
>
> Some of the items here are dependent on ceph-mgr (like the enhanced
> status views, client statistics), some aren't.  The general theme is
> to make things less arcane, and make the state of the system easier to
> understand.
>
> Please share your thoughts.
>
> Cheers,
> John
>
>
> Simpler kernel client setup
>  * allow mount.ceph to use the same keyring file that the FUSE client
> uses, instead of requiring users to strip the secret out of that file
> manually. (http://tracker.ceph.com/issues/16656)
>
> Simpler multi-fs use from ceph-fuse
>  * A nicer syntax than having to pass --client_mds_namespace
>  * A way to specify the chosen filesystem in fstab
>
> Mount-less administrative shell/commands:
>  * A lightweight python shell enabling admins to manipulate their
> filesystem without a full blown client mount
>  * Friendlier commands than current setxattr syntax for layouts and quotas
>  * Enable administrators to inspect the filesystem (ls, cd, stat, etc)
>  * Enable administrators to configure things like directories for
> users with quotas, mapping directories to pools
>
> CephFS daemon/recovery status view:
>  * Currently we see the text status of replay/clientreplay etc in "ceph status"
>  * A more detailed "ceph fs status" view that breaks down each MDS
> daemon's state
>  * What we'd really like to see in these modes is progress (% of
> segments replayed, % of clients replayed, % of clients reconnected)
> and timing information (e.g. in reconnect, something like "waiting for
> 1 client for another 30 seconds")
>  * Maybe also display some other high level perf stats per-MDS like
> client requests per second within this view.
>
> CephFS full system dstat-like view
>  * Currently have "daemonperf mds.<foo>" asok mechanism, which is
> local to one MDS and does not give OSD statistics
>  * Add a "ceph fs perf" command that fuses multi-mds data with OSD
> data to give users a single view of the level of metadata and data IO
> across the system
>
> Client statistics
>  * Implement the "live performance probes" mechanism
> http://tracker.ceph.com/projects/ceph/wiki/Live_Performance_Probes
>  * This is the same infrastructure as would be used for e.g. "rbd top"
> image listing.
>  * Initially could just be a "client top" view with 5-10 key stats per
> client, where we collect data for the busiest 10-20 clients (on modest
> size systems this likely to be all clients in practice)
>  * Full feature would have per-path filtering, so that admin could say
> "which subtree is busy?  OK, which client is busy within that
> subtree?".
>
> Orchestrated backward scrub (aka cephfs-data-scan, #12143):
>  * Wrap it in a central CLI that runs a pool of workers
>  * Those workers could be embedded in standby mgrs, in standby mdss,
> or standalone
>  * Need a work queue type mechanism, probably via RADOS objects.
>  * This is http://tracker.ceph.com/issues/12143
>
> Single command hard client eviction:
>  * Wrap the process of blacklisting a client *and* evicting it from
> all MDS daemons
>  * Similar procedure currently done in CephFSVolumeClient.evict
>  * This is http://tracker.ceph.com/issues/9754
>
> Simplified client auth caps creation:
>  * Wrap the process of creating a client identify that has just the
> right MDS+OSD capabilities for accessing a particular filesystem
> ("ceph fs authorize client.foo" instead of "ceph auth get-or-create
> ... ..."
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