> -----Original Message----- > From: ceph-users [mailto:ceph-users-boun...@lists.ceph.com] On Behalf Of Wido > den Hollander > Sent: 10 January 2017 07:54 > To: ceph new <ceph-users@lists.ceph.com>; Stuart Harland > <s.harl...@livelinktechnology.net> > Subject: Re: [ceph-users] Write back cache removal > > > > Op 9 januari 2017 om 13:02 schreef Stuart Harland > > <s.harl...@livelinktechnology.net>: > > > > > > Hi, > > > > We’ve been operating a ceph storage system storing files using librados > > (using a replicated pool on rust disks). We implemented a > cache over the top of this with SSDs, however we now want to turn this off. > > > > The documentation suggests setting the cache mode to forward before > > draining the pool, however the ceph management > controller spits out an error about this saying that it is unsupported and > hence dangerous. > > > > What version of Ceph are you running? > > And can you paste the exact command and the output? > > Wido
Hi Wido, I think this has been discussed before and looks like it might be a current limitation. Not sure if it's on anybody's radar to fix. https://www.mail-archive.com/ceph-users@lists.ceph.com/msg24472.html Nick > > > The thing is I cannot really locate any documentation as to why it’s > > considered unsupported and under what conditions it is expected > to fail: I have read a passing comment about EC pools having data corruption, > but we are using replicated pools. > > > > Is this something that is safe to do? > > > > Otherwise I have noted the read proxy mode of cache tiers which is > > documented as a mechanism to transition from write back to > disabled, however the documentation is even sparser on this than forward > mode. Would this be a better approach if there is some > unsupported behaviour in the forward mode cache option? > > > > Any thoughts would be appreciated - we really cannot afford to corrupt the > > data, and I really do not want to have to do some > manual software based eviction on this data. > > > > regards > > > > Stuart > > > > > > − Stuart Harland: > > Infrastructure Engineer > > Email: s.harl...@livelinktechnology.net > > <mailto:s.harl...@livelinktechnology.net> > > > > > > > > LiveLink Technology Ltd > > McCormack House > > 56A East Street > > Havant > > PO9 1BS > > > > IMPORTANT: The information transmitted in this e-mail is intended only for > > the person or entity to whom it is addressed and may > contain confidential and/or privileged information. If you are not the > intended recipient of this message, please do not read, copy, use > or disclose this communication and notify the sender immediately. Any review, > retransmission, dissemination or other use of, or > taking any action in reliance upon this information by persons or entities > other than the intended recipient is prohibited. Any views or > opinions presented in this e-mail are solely those of the author and do not > necessarily represent those of LiveLink. This e-mail > message has been checked for the presence of computer viruses. However, > LiveLink is not able to accept liability for any damage > caused by this e-mail. > > > > > > > > _______________________________________________ > > ceph-users mailing list > > ceph-users@lists.ceph.com > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
