From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Haas Subject: Re: [ceph-users] Status of snapshots in CephFS Date: Wed, 24 Sep 2014 19:27:19 +0100 Message-ID: <54230D07.8000108@hastexo.com> References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="HIrrv24bSQMwvGKVULjgvnbbwHWd7Txcr" Return-path: Received: from mail-wi0-f181.google.com ([209.85.212.181]:42357 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752661AbaIXS1X (ORCPT ); Wed, 24 Sep 2014 14:27:23 -0400 Received: by mail-wi0-f181.google.com with SMTP id z2so7893920wiv.14 for ; Wed, 24 Sep 2014 11:27:21 -0700 (PDT) In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Sage Weil Cc: "ceph-users@lists.ceph.com" , "ceph-devel@vger.kernel.org" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --HIrrv24bSQMwvGKVULjgvnbbwHWd7Txcr Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Fri, Sep 19, 2014 at 5:25 PM, Sage Weil wrote: > On Fri, 19 Sep 2014, Florian Haas wrote: >> Hello everyone, >> >> Just thought I'd circle back on some discussions I've had with people >> earlier in the year: >> >> Shortly before firefly, snapshot support for CephFS clients was >> effectively disabled by default at the MDS level, and can only be >> enabled after accepting a scary warning that your filesystem is highly= >> likely to break if snapshot support is enabled. Has any progress been >> made on this in the interim? >> >> With libcephfs support slowly maturing in Ganesha, the option of >> deploying a Ceph-backed userspace NFS server is becoming more >> attractive -- and it's probably a better use of resources than mapping= >> a boatload of RBDs on an NFS head node and then exporting all the data= >> from there. Recent snapshot trimming issues notwithstanding, RBD >> snapshot support is reasonably stable, but even so, making snapshot >> data available via NFS, that way, is rather ugly. In addition, the >> libcephfs/Ganesha approach would obviously include much better >> horizontal scalability. > > We haven't done any work on snapshot stability. It is probably moderat= ely > stable if snapshots are only done at the root or at a consistent point = in > the hierarcy (as opposed to random directories), but there are still so= me > basic problems that need to be resolved. I would not suggest deploying= > this in production! But some stress testing woudl as always be very > welcome. :) OK, on a semi-related note: is there any reasonably current authoritative list of features that are supported and unsupported in either ceph-fuse or kernel cephfs, and if so, at what minimal version? The most comprehensive overview that seems to be available is one from Greg, which however is a year and a half old: http://ceph.com/dev-notes/cephfs-mds-status-discussion/ >> In addition, https://github.com/nfs-ganesha/nfs-ganesha/wiki/ReleaseNo= tes_2.0#CEPH >> states: >> >> "The current requirement to build and use the Ceph FSAL is a Ceph >> build environment which includes Ceph client enhancements staged on >> the libwipcephfs development branch. These changes are expected to be >> part of the Ceph Firefly release." >> >> ... though it's not clear whether they ever did make it into firefly. >> Could someone in the know comment on that? > > I think this is referring to the libcephfs API changes that the cohortf= s > folks did. That all merged shortly before firefly. Great, thanks for the clarification. > By the way, we have some basic samba integration tests in our regular > regression tests, but nothing based on ganesha. If you really want thi= s > to the work, the most valuable thing you could do would be to help > get the tests written and integrated into ceph-qa-suite.git. Probably = the > biggest piece of work there is creating a task/ganesha.py that installs= > and configures ganesha with the ceph FSAL. Hmmm, given the excellent writeup that Niels de Vos of Gluster fame wrote about this topic, I might actually be able to cargo-cult some of what's in the Samba task and adapt it for ganesha. Sorry while I'm being ignorant about Teuthology: what platform does it normally run on? I ask because I understand most of your testing is done on Ubuntu, and Ubuntu currently doesn't ship a Ganesha package, which would make the install task a bit more complex. Cheers, Florian --HIrrv24bSQMwvGKVULjgvnbbwHWd7Txcr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUIw0HAAoJEEqtGHdMPKEn6MgP/2gBtPH6FlA5bp6iv1kIUEQI +iM8BZv2WhWTB0ytRU1TzEc2GEZ/5Z4eEVjIKCP+tm2zpvd8RV4C2bG6vgX+DvtL NP3NGjypWH6kSr0yt+Q4IlP1fFdmoQ4KKCSk7uPI84rT8KGY+g/mF4Bf9P0YhrSA HBI1/nuS9Uy8RrNHvnmL/bjZTs6jDA4h2idbfzPnSPEHQlf4K0MI2aMidTG6IAVd dbZEQGdZA1mqy2jeEoz6UVQo2JvbcNxt7FAjgM8nLPpImXj34nplW11HeU+jGJln +yAVX94D+iYtV2BczAz2oGbLDLStcxhpeAO6rHRSK97/QSbonSrEDJeE5ZD+r9ga 2OXC9m93USojycGTNxG+e/zW4k6e8r7CRTc40AxPM08i285rDa7n4XrdgCyz44xc RSIDN7qYvuYqbrPAPQ/sLvsnCgAPie5bXkx/IFz8ezwUXwxUBA3k2E+HliJLmehD ivBfRAzDXIbHsUWnAPKXRLtGEMCRYd5B31DvFjBNtzO4lqOP5BMERkvs3LCCe+GZ XirdjoR12UDtVyBJpl+heuKlwcSNkycVmGiVz2/DFacnjiqaG2pFFSQoN4xgWfEq OI2I1dL5pE9icOX0dHypYeOdK5rlPgZ/USeHetVaSzA9VcpuqvzDSK890AON2+4E ZCACXuPcse6C0dMSMD5B =b70K -----END PGP SIGNATURE----- --HIrrv24bSQMwvGKVULjgvnbbwHWd7Txcr--