Hi all Does anyone use read-subvolume? Has anyone tested read-subvolume? Does read-subvolume work in such a way that if the file is present on the local node the local copy is used rather than a remote one? Alternatively is there any way to configure (or patch) gluster to always prefer the local file? I have read everything available and have found no answer. Unison works very well in our environment but is not real time and needs to be run every few minutes and/or be kicked off with inotify. If I could get gluster to always read the local copy it would be a much better drop in replacement. This is a small scale deployment not a massive cluster but I can imagine there are many potential users of gluster in this mode. It should beat unison and similar solutions in every way - but it doesn't because it is reading from the network even when it has a local up-to-date copy. This can't be intended behaviour. So what have I configured wrong? Thanks in advance Allan On 02/07/13 13:38, Allan Latham wrote: > Hi everyone > > I have installed 3.3.1-1 from the Debian repository you provide. > > I am using a simple 2 node cluster and running in replication mode. The > connection between the nodes is limited to 100MB/sec (that's bits not > bytes!). Usage will be mainly for read access and since there is always > a local copy available [ exactly 2 replicas on exactly 2 machines ] I > expect very fast read performance. Writes are low volume and very > infrequent - performance is not an issue. > > Almost everything works as I would expect. > > Write speed is limited to 10Mb (bytes) per second which is what I would > expect and is adequate for the application. > > But read speed is either super fast or 10Mb/sec. i.e. read operations > take place on the local copy or the remote seemingly at random. > > This not the 'small files problem'. I am aware that Gluster must use > network access for stat() etc. This is all about where the data comes > from on a read(). If I do an m5dum on a 200Mb file it takes either half > a second or 18 seconds. > > There is an option read-subvolume. > > I have tried to understand how this works from the documentation > available and from the few examples on the web. > > I have added the option using: > > gluster volume set X read-subvolume Y > > It has no effect even after stopping and starting the volume, > remounting, restarting gluster servers etc. > > What's more I fail to see how this option could ever work at all. The > configuration changes caused by the above command are rolled out to both > nodes - but what is right for one node is exactly the wrong > configuration for the other node. > > Configs attached are in /var/lib/glusterd/vols/shared except > glusterd.vol which is in /etc/glusterfs. > > Here is the output of the mount command filtered to just the glusterfs > mount: > > 10.255.255.1:/shared on /gluster/rw/shared type fuse.glusterfs > (rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072) > > 10.255.255.1 is local to this host. > > I would be very thankful if someone can enlighten me. I am obviously > configuring this wrong. I may have missed something important. > > Best regards to all > > Allan > > > > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org > http://supercolony.gluster.org/mailman/listinfo/gluster-users >
