At 03:11 AM 3/10/2009, Christian Meisinger wrote: >hi there. > > >i've 6 load-balanced webservers running with apache 2.0. >right now we use unison to upload file changes from the developers to server 1 >and then 'sync' those changes to 2, 3 andsoon. > >additionally if a file is created on one of the servers (like a >temporary download created with php) >we 'sync' that file with scp. for safety there are unisons running >every 10mins on some servers >to ensure all files are available on every server. > >right now it's not a problem with only 6 servers but i'm pretty sure >it will become a big problem >with more servers... > > >so i started some tests GlusterFS 2.0.0rc2. >right now i think two setups may suit us: > >layout 1: > node1-replicate-node2 \ > node3-replicate-node4 - --> distribute ( like raid0 over 3 x raid1 ) > node5-replicate-node6 / > >or > >layout 2: > node1-replicate-node2-replicate-node3 \ > node4-replicate-node5-replicate-node6 - --> distribute ( like > raid0 over 2 x raid5 :) ) > >i think layout 1 should be ok, because until now i've never seen 2 >servers crash at the same time. I'd definitely recommend layout 1 over layout 2. the more nodes in an AFR brick the more performance issues you may have. >my problem is: what happens if we get additional servers? if you add them in pairs, you're in good shape, otherwise, you need to do a 3-node afr brick until you have an even number of servers then do something different. >i've tested layout 1 with 4 nodes, shutdown GLFS, added >node5-replicate-node6 to the distrubite translator and started >again. files were ok but i got alot of GLFS errors in the log files. >can i safely ignore them? it depends on which errors they are.. you'd have to use your judgement. whenever I know a node has failed in an AFR pair, I typicall turn on "favorite-child" in the other one, remount, then bring up the down server. then run ls -lR on the server that didn't crash. once done, remount without favorite child. but this way you don't get the i/o errors (although I think those are fixed in Rc3 or 4) you might be seeing. >i know the manual says: use distribute for fresh installations else unify. >still i'm curious if it would work with distribute. > >btw. for GlusterFS version 2.0 is AFR = replicate? yes
