> Op 10 januari 2017 om 9:52 schreef Nick Fisk <nick@xxxxxxxxxx>: > > > > -----Original Message----- > > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of Wido den Hollander > > Sent: 10 January 2017 07:54 > > To: ceph new <ceph-users@xxxxxxxxxxxxxx>; Stuart Harland <s.harland@xxxxxxxxxxxxxxxxxxxxxx> > > Subject: Re: Write back cache removal > > > > > > > Op 9 januari 2017 om 13:02 schreef Stuart Harland <s.harland@xxxxxxxxxxxxxxxxxxxxxx>: > > > > > > > > > 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@xxxxxxxxxxxxxx/msg24472.html > Might be, but afaik they are using their own application which writes to RADOS using librados, not RBD. Is that correct Stuart? Wido > 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.harland@xxxxxxxxxxxxxxxxxxxxxx <mailto:s.harland@xxxxxxxxxxxxxxxxxxxxxx> > > > > > > > > > > > > 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@xxxxxxxxxxxxxx > > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > _______________________________________________ > > ceph-users mailing list > > ceph-users@xxxxxxxxxxxxxx > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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