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? > 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? > > 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
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