Putting all machines on the same switch will at least save a switch-hop, cutting latency by 1/3 in the ideal case which is an improvement. If it will matter for your application, I do not know :) On 1/30/2012 6:45 PM, Dan Bretherton wrote: > Thanks for the advice Peter, >> You could get a cisco switch that supports cut through instead of >> store-and-forward, for lower latency. > Interesting option, but those cost ~?10K and are out of our price > range unfortunately. The "cut through" switching technology is also > available in Dell's new Force 10 range I believe. > >> Other than that, compare the port to port forwarding times and see if >> there is a difference between the switches you are looking at (probably >> not) and make your decision based on that. > You're right, there isn't much of a difference between the forwarding > rate of the 5548 and the 6248, both are about 100Mpps. They also have > a similar bandwidth of about 180Gbps. However the 7048 does better on > both measures, with forwarding rate of 160Mpps and a bandwidth of > 224Gbps. Unfortunately the 7048 costs five times as much as the 5548, > and I don't know if the users would notice any difference at all. I > expect some would and some wouldn't. > > -Dan. > > On 01/27/2012 01:48 PM, gluster-users-request at gluster.org wrote: >> Date: Fri, 27 Jan 2012 14:16:36 +0100 >> From: Peter Linder<peter.linder at fiberdirekt.se> >> Subject: Re: Switch recommendations >> To:gluster-users at gluster.org >> Message-ID:<4F22A3B4.8000008 at fiberdirekt.se> >> Content-Type: text/plain; charset=ISO-8859-1; format=flowed >> >> You could get a cisco switch that supports cut through instead of >> store-and-forward, for lower latency. >> >> Other than that, compare the port to port forwarding times and see if >> there is a difference between the switches you are looking at (probably >> not) and make your decision based on that. Consider connecting >> everything to two switches, for failover in case a switch breaks? >> >> On 1/27/2012 2:04 PM, Dan Bretherton wrote: >>> > Dear All, >>> > I need to buy a bigger GigE switch for my GlusterFS cluster and I am >>> > trying to decide whether or not a much more expensive one would be >>> > justified. I have limited experience with networking so I don't >>> know >>> > if it would be appropriate to spend ?500, ?1500 or ?3500 for a >>> 48-port >>> > switch. Those rough costs are based on a comparison of 3 Dell >>> > Powerconnect switches: the 5548 (bigger version of what we have >>> now), >>> > the 6248 and the 7048. The servers in the cluster are nothing >>> special >>> > - mostly Supermicro with SATA drives and 1GigE network adapters. I >>> > can only justify spending more than ~?500 if I can be sure that >>> users >>> > would notice the difference. Some of the users' applications do >>> lots >>> > of small reads and writes, and they do run much more slowly if >>> all the >>> > servers are not connected to the same switch, as is the case now >>> while >>> > I don't have a big enough switch. Any advice or comments would be >>> > much appreciated. >>> > >>> > Regards >>> > Dan.
