[Gluster-users] about HA infrastructure for hypervisors

Thu Jun 28 10:40:38 UTC 2012

Interesting info Brian,
I am surprised with this actually. Would always expect 10Gig have a very good and low latency times. Obviously I wouldn't expect copper be exactly the same as Fibre due the losses, but not much behind either.

Please share any future results you get, as it's quiet value information for people before designing their systems.

Regards,

Fernando

-----Original Message-----
From: gluster-users-bounces at gluster.org [mailto:gluster-users-bounces at gluster.org] On Behalf Of Brian Candler
Sent: 28 June 2012 11:33
To: Nicolas Sebrecht
Cc: gluster-users
Subject: Re: [Gluster-users] about HA infrastructure for hypervisors

On Thu, Jun 28, 2012 at 11:25:20AM +0200, Nicolas Sebrecht wrote:
> We excluded ethernet due to searches on the web. It appeared that 
> ethernet has bad latency.

I read it on the web, it must be true :-)

As I said: don't use 10GE over CAT6/RJ45 (10Gbase-T). That does indeed have poor latency.  As I understand it: in order to get such high data rates over copper, it has to employ mechanisms similar to DSL lines, like interleaving, which means 10G has comparable or even higher latency than 1G.  Switches with all 10Gbase-T ports are expensive, only available from a couple of vendors, and consume a lot of power.

However switches with SFP+ ports don't have these problems. For short reach you can use SFP+ direct attach cables, and for long reach use fibre.

http://en.wikipedia.org/wiki/10-gigabit_Ethernet

I have been working with Intel X520-DA2 NICs and a Netgear XSM7224S switch, and direct-attach cables (3m Netgear AXC763, 5m Intel)

This all works fine, although with older versions of Linux I had to build the latest Intel drivers from their website to fix problems with the links going down every day or two.

Regards,

Brian.
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