On Tue, Oct 4, 2016 at 11:30 PM, John Spray <jspray@xxxxxxxxxx> wrote: > On Tue, Oct 4, 2016 at 5:09 PM, Stephen Horton <shorton3@xxxxxxxxx> wrote: >> Thank you John. Both my Openstack hosts and the VMs are all running 4.4.0-38-generic #57-Ubuntu SMP x86_64. I can see no evidence that any of the VMs are holding large numbers of files open. If this is likely a client bug, is there some process I can follow to file a bug report? > > It might be worthwhile to file a bug report with Ubuntu, as they'd be > the ones who would ideally backport fixes to their stable kernels (in > this instance it's hard to know if this is a bug in the latest kernel > code or something fixed since 4.4). > > It would be really useful if you could try installing the latest > released kernel on the clients and see if the issue persists: if so > then a ticket on tracker.ceph.com will be a priority for us to fix. > > CCing Zheng -- are there any noteworthy fixes between 4.4 and latest > kernel that might be relevant? No bug found in this area since 4.4 > > John > > >> >>> On Oct 4, 2016, at 9:39 AM, John Spray <jspray@xxxxxxxxxx> wrote: >>> >>>> On Tue, Oct 4, 2016 at 4:27 PM, Stephen Horton <shorton3@xxxxxxxxx> wrote: >>>> Adding that all of my ceph components are version: >>>> 10.2.2-0ubuntu0.16.04.2 >>>> >>>> Openstack is Mitaka on Ubuntu 16.04x. Manila file share is 1:2.0.0-0ubuntu1 >>>> >>>> My scenario is that I have a 3-node ceph cluster running openstack mitaka. Each node has 256gb ram, 14tb raid 5 array. I have 30 VMs running in openstack; all are mounted to the Manila file share using cephfs native kernel client driver. Each VM user has put 10-20 gb of files on the share, but most of this is back-up, so IO requirement is very low. However, I initially tried using ceph-fuse but performance latency was poor. Moving to kernel client driver for mounting the share has improved performance greatly. However, I am getting the cache pressure issue. >>> >>> Aside: bear in mind that the kernel client doesn't support quotas, so >>> any size limits you set on your Manila shares won't be respected. >>> >>>> Can someone help me with the math to properly size the mds cache? How do I know if the cache size is too small (I think very few files in-use at any given time) versus the clients are broken and not releasing cache properly? >>> >>> It's almost never the case that your cache is too small unless your >>> workload is holding a silly number of files open at one time -- assume >>> this is a client bug (although some people work around it by creating >>> much bigger MDS caches!) >>> >>> You've mentioned the versions of openstack/ubuntu/ceph, but what >>> kernel are you running? >>> When the warnings happen?(client is idle or client is under load). Are there any kernel warning when umounting the client that emitted the warning? Regards Yan, Zheng >>> John >>> >>>> Thank you! >>>> _______________________________________________ >>>> 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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