Just a guess, but how are the writes being done? If they're being written in zillions of tiny writes, then what you may be seeing is described here: <http://moo.nac.uci.edu/~hjm/bduc/BDUC_USER_HOWTO.html#writeperfongl> and the following stanza on named pipes. This is often the case with the large files being used in NGS/HTS where the fasta/fastq files are composed of millions of short (60-100 char) lines of characters and are typically written line-by-line. hjm On Wednesday, January 16, 2013 02:47:37 PM Ayelet Shemesh wrote: > Hi to all Gluster experts, > > I have a cluster of 10 machines exposing a volume into which 12 other > machines do many writes of large files (~100-300MB each). > In general I'm very happy with gluster. It's a great solution, and is quite > stable (thanks for the great work!). > > However, I have a problem which I was unable to solve yet, nor find any > solution to in the documentation or on this list archive. > > When the client machines write locally, and then just copy the files they > created to the gluster mount - everything works great. > When the client machines write directly to the gluster mounted volume I get > a huge performance hit. > In one specific test case the difference was 20 minutes for the copy and 8 > hours for the direct write. > > I tried to set the iocache attributes of write-behind-window and > flush-behind, but to no avail. > > I will very much appreciate your help in solving this problem. > > Thanks, > Ayelet --- 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.
