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, [email protected] wrote:
Date: Fri, 27 Jan 2012 14:16:36 +0100
From: Peter Linder<[email protected]>
Subject: Re: [Gluster-users] Switch recommendations
To:[email protected]
Message-ID:<[email protected]>
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.
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