Hi, On 03/08/2018 10:52 AM, Manoj Pillai wrote: > On Wed, Mar 7, 2018 at 8:29 PM, Rik Theys <rik.th...@esat.kuleuven.be > <mailto:rik.th...@esat.kuleuven.be>> wrote: > > I'm currently testing gluster (3.12, now 3.13) on older machines[1] and > have created a replica 3 arbiter 1 volume 2x(2+1). I seem to run in all > sorts of (performance) problems. I must be doing something wrong but > I've tried all sorts of benchmarks and nothing seems to make my setup > live up to what I would expect from this hardware. > > * I understand that gluster only starts to work well when multiple > clients are connecting in parallel, but I did expect the single client > performance to be better. > > * Unpacking the linux-4.15.7.tar.xz file on the brick XFS filesystem > followed by a sync takes about 1 minute. Doing the same on the gluster > volume using the fuse client (client is one of the brick servers) takes > over 9 minutes and neither disk nor cpu nor network are reaching their > bottleneck. Doing the same over NFS-ganesha (client is a workstation > connected through gbit) takes even longer (more than 30min!?). > > I understand that unpacking a lot of small files may be the worst > workload for a distributed filesystem, but when I look at the file sizes > of the files in our users' home directories, more than 90% is smaller > than 1MB. > > * A file copy of a 300GB file over NFS 4 (nfs-ganesha) starts fast > (90MB/s) and then drops to 20MB/s. When I look at the servers during the > copy, I don't see where the bottleneck is as the cpu, disk and network > are not maxing out (on none of the bricks). When the same client copies > the file to our current NFS storage it is limited by the gbit network > connection of the client. > > > Both untar and cp are single-threaded, which means throughput is mostly > dictated by latency. Latency is generally higher in a distributed FS; > nfs-ganesha has an extra hop to the backend, and hence higher latency > for most operations compared to glusterfs-fuse. > > You don't necessarily need multiple clients for good performance with > gluster. Many multi-threaded benchmarks give good performance from a > single client. Here for e.g., if you run multiple copy commands in > parallel from the same client, I'd expect your aggregate transfer rate > to improve. > > Been a long while since I looked at nfs-ganesha. But in terms of upper > bounds for throughput tests: data needs to flow over the > client->nfs-server link, and then, depending on which servers the file > is located on, either 1x (if the nfs-ganesha node is also hosting one > copy of the file, and neglecting arbiter) or 2x over the s2s link. With > 1Gbps links, that means an upper bound between 125 MB/s and 62.5 MB/s, > in the steady state, unless I miscalculated.
Yes, you are correct, but the speeds I'm seeing are far below 62.5MB/s. In the untar case, I fully understand the overhead as there a lot of small files and therefore a lot of metadata overhead. In the sequential write the speed should be much better as latency is/should be less of an issue here? I've been trying to find some documentation on nfs-ganesha but everything I find seems to be outdated :-(. The documentation on their wiki states: " Version 2.0 This version is in active development and is not considered stable enough for production use. Its documentation is still incomplete. " Their latest version is 2.6.0... Also I can not find what changed between 2.5 and 2.6. Sure I can look at he git commits, but there is no maintained changes/changelog,... >From what I've read nfs-ganesha should be able cache a lot of data, but I can't find any good documentation on how to configure this. Regards, Rik -- Rik Theys System Engineer KU Leuven - Dept. Elektrotechniek (ESAT) Kasteelpark Arenberg 10 bus 2440 - B-3001 Leuven-Heverlee +32(0)16/32.11.07 ---------------------------------------------------------------- <<Any errors in spelling, tact or fact are transmission errors>> _______________________________________________ Gluster-users mailing list Gluster-users@gluster.org http://lists.gluster.org/mailman/listinfo/gluster-users
