Indeed, well understood. As a shorter term workaround, if you have control over the VMs, you could always just slice out an LVM volume from local SSD/NVMe and pass it through to the guest. Within the guest, use dm-cache (or similar) to add a cache front-end to your RBD volume. Others have also reported improvements by using the QEMU x-data-plane option and RAIDing several RBD images together within the VM. -- Jason Dillaman ----- Original Message ----- > From: "Daniel Niasoff" <daniel@xxxxxxxxxxxxxx> > To: "Jason Dillaman" <dillaman@xxxxxxxxxx> > Cc: ceph-users@xxxxxxxxxxxxxx > Sent: Tuesday, March 15, 2016 9:32:50 PM > Subject: RE: Local SSD cache for ceph on each compute node. > > Thanks. > > Reassuring but I could do with something today :) > > -----Original Message----- > From: Jason Dillaman [mailto:dillaman@xxxxxxxxxx] > Sent: 16 March 2016 01:25 > To: Daniel Niasoff <daniel@xxxxxxxxxxxxxx> > Cc: ceph-users@xxxxxxxxxxxxxx > Subject: Re: Local SSD cache for ceph on each compute node. > > The good news is such a feature is in the early stage of design [1]. > Hopefully this is a feature that will land in the Kraken release timeframe. > > [1] > http://tracker.ceph.com/projects/ceph/wiki/Rbd_-_ordered_crash-consistent_write-back_caching_extension > > -- > > Jason Dillaman > > > ----- Original Message ----- > > From: "Daniel Niasoff" <daniel@xxxxxxxxxxxxxx> > > To: ceph-users@xxxxxxxxxxxxxx > > Sent: Tuesday, March 15, 2016 8:47:04 PM > > Subject: Local SSD cache for ceph on each compute node. > > > > Hi, > > > > Let me start. Ceph is amazing, no it really is! > > > > But a hypervisor reading and writing all its data off the network off > > the network will add some latency to read and writes. > > > > So the hypervisor could do with a local cache, possible SSD or even NVMe. > > > > Spent a while looking into this but it seems really strange that few > > people see the value of this. > > > > Basically the cache would be used in two ways > > > > a) cache hot data > > b) writeback cache for ceph writes > > > > There is the RBD cache but that isn't disk based and on a hypervisor > > memory is at a premium. > > > > A simple solution would be to put a journal on each compute node and > > get each hypervisor to use its own journal. Would this work? > > > > Something like this > > http://sebastien-han.fr/images/ceph-cache-pool-compute-design.png > > > > Can this be achieved? > > > > A better explanation of what I am trying to achieve is here > > > > http://opennebula.org/cached-ssd-storage-infrastructure-for-vms/ > > > > This talk if it was voted in looks interesting - > > https://www.openstack.org/summit/austin-2016/vote-for-speakers/Present > > ation/6827 > > > > Can anyone help? > > > > Thanks > > > > Daniel > > _______________________________________________ > > 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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