Hello, I found other strange thing. On the dd-test (dd if=/dev/zero of=2testbin bs=1M count=1024 oflag=direct) my volume shows only 18-19MB/s. Full network speed is 90-110MB/s, storage speed - ~200MB/s. Volume type - replicated-distributed, 2 replicas, 4 nodes. Volumes mounted via fuse with direct-io=enable option. Its sooo slooow, right? 2013/3/5 harry mangalam <harry.mangalam at uci.edu> > This kind of info is surprisingly hard to obtain. The gluster docs do > contain > some of it, ie: > > <http://community.gluster.org/a/linux-kernel-tuning-for-glusterfs/> > > I also found well-described kernel tuning parameters in the FHGFS wiki (as > another distibuted fs, they share some characteristics) > > http://www.fhgfs.com/wiki/wikka.php?wakka=StorageServerTuning > > and more XFS tuning filesystem params here: > > <http://www.mythtv.org/wiki/Optimizing_Performance#Further_Information> > > and here: > <http://www.mysqlperformanceblog.com/2011/12/16/setting-up-xfs-the-simple- > edition> > > But of course, YMMV and a number of these parameters conflict and/or have > serious tradeoffs, as you discovered. > > LSI recently loaned me a Nytro SAS controller (on-card SSD-cached) which > seems > pretty phenomenal on a single brick (and is predicted to perform well > based on > their profiling), but am waiting for another node to arrive before I can > test > it under true gluster conditions. Anyone else tried this hardware? > > hjm > > On Tuesday, March 05, 2013 12:34:41 PM Nikita A Kardashin wrote: > > Hello all! > > > > This problem is solved by me today. > > Root of all in the incompatibility of gluster cache and kvm cache. > > > > Bug reproduces if KVM virtual machine created with cache=writethrough > > (default for OpenStack) option and hosted on GlusterFS volume. If any > other > > (cache=writeback or cache=none with direct-io) cacher used, performance > of > > writing to existing file inside VM is equal to bare storage (from host > > machine) write performance. > > > > I think, it must be documented in Gluster and maybe filled a bug. > > > > Other question. Where I can read something about gluster tuning (optimal > > cache size, write-behind, flush-behind use cases and other)? I found only > > options list, without any how-to or tested cases. > > > > > > 2013/3/5 Toby Corkindale <toby.corkindale at strategicdata.com.au> > > > > > On 01/03/13 21:12, Brian Candler wrote: > > >> On Fri, Mar 01, 2013 at 03:30:07PM +0600, Nikita A Kardashin wrote: > > >>> If I try to execute above command inside virtual machine (KVM), > > >>> first > > >>> time all going right - about 900MB/s (cache effect, I think), > but if > > >>> > > >>> I > > >>> > > >>> run this test again on existing file - task (dd) hungs up and > can be > > >>> stopped only by Ctrl+C. > > >>> Overall virtual system latency is poor too. For example, apt-get > > >>> upgrade upgrading system very, very slow, freezing on "Unpacking > > >>> replacement" and other io-related steps. > > >>> Does glusterfs have any tuning options, that can help me? > > >> > > >> If you are finding that processes hang or freeze indefinitely, this is > > >> not > > >> a question of "tuning", this is simply "broken". > > >> > > >> Anyway, you're asking the wrong person - I'm currently in the process > of > > >> stripping out glusterfs, although I remain interested in the project. > > >> > > >> I did find that KVM performed very poorly, but KVM was not my main > > >> application and that's not why I'm abandoning it. I'm stripping out > > >> glusterfs primarily because it's not supportable in my environment, > > >> because > > >> there is no documentation on how to analyse and recover from failure > > >> scenarios which can and do happen. This point in more detail: > > >> http://www.gluster.org/**pipermail/gluster-users/2013-** > > >> January/035118.html< > http://www.gluster.org/pipermail/gluster-users/2013-J > > >> anuary/035118.html> > > >> > > >> The other downside of gluster was its lack of flexibility, in > particular > > >> the > > >> fact that there is no usage scaling factor on bricks, so that even > with a > > >> simple distributed setup all your bricks have to be the same size. > Also, > > >> the object store feature which I wanted to use, has clearly had hardly > > >> any > > >> testing (even the RPM packages don't install properly). > > >> > > >> I *really* wanted to deploy gluster, because in principle I like the > idea > > >> of > > >> a virtual distribution/replication system which sits on top of > existing > > >> local filesystems. But for storage, I need something where > operational > > >> supportability is at the top of the pile. > > > > > > I have to agree; GlusterFS has been in use here in production for a > while, > > > and while it mostly works, it's been fragile and documentation has been > > > disappointing. Despite 3.3 being in beta for a year, it still seems to > > > have > > > been poorly tested. For eg, I can't believe almost no-one else noticed > > > that > > > the log files were busted.. nor that the bug report has been around for > > > quarter of a year without being responded to or fixed. > > > > > > I have to ask -- what are you moving to now, Brian? > > > > > > -Toby > > > > > > > > > ______________________________**_________________ > > > Gluster-users mailing list > > > Gluster-users at gluster.org > > > http://supercolony.gluster.**org/mailman/listinfo/gluster-**users< > http://s > > > upercolony.gluster.org/mailman/listinfo/gluster-users> > > --- > Harry Mangalam - Research Computing, OIT, Rm 225 MSTB, UC Irvine > [m/c 2225] / 92697 Google Voice Multiplexer: (949) 478-4487 > 415 South Circle View Dr, Irvine, CA, 92697 [shipping] > MSTB Lat/Long: (33.642025,-117.844414) (paste into Google Maps) > --- > "Something must be done. [X] is something. Therefore, we must do it." > Bruce Schneier, on American response to just about anything. > -- With best regards, differentlocal (www.differentlocal.ru | differentlocal at gmail.com), System administrator. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://supercolony.gluster.org/pipermail/gluster-users/attachments/20130312/01c3aeac/attachment-0001.html>
