[Gluster-users] Switch recommendations

Brian Candler B.Candler at pobox.com
Fri Jan 27 13:59:41 UTC 2012

On Fri, Jan 27, 2012 at 01:04:39PM +0000, Dan Bretherton wrote:
> 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.

If you already have 5524s then they are apparently stackable using a HDMI
cable, have you tried that?

I have bad experience with Powerconnect 5524's, but maybe you're just not
tickling the same bugs I found (e.g.  multicast problems, failing to learn
MAC addresses)

Haven't had these same problems with Netgear GSM7224V2, but then maybe they
have a different set of bugs :-)

> 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.

If it's consistently a little slower for each individual file read and
written, then it sounds like this usage pattern is extremely
latency-sensitive.  If it seems to be in bursts then maybe you are getting
small amounts of packet loss, which is causing TCP to back off.

Side note: if you are latency-sensitive then don't even think about using
10Gig over RJ45 - it actually has a higher latency than 1G.  But 10Gig over
SFP+ is fine.



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