RE: 10Gbps latency

Hi Marc,

I face these debates/questions on almost a daily basis so I feel for you man...

Can you confirm the following:

1. Are you trying to access iscsi storage or is this simply oracle replication traffic?

2. Are you using the very latest nic drivers on each server?

3. Can you confirm disk queue, raid level, raid performance and other NON-NETWORK related things have been checked and blessed by the server priest ordained at your location?

Thanks,

Joe

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of marc abel
Sent: Monday, July 11, 2011 9:48 AM
To: ccielab_at_groupstudy.com
Subject: OT: 10Gbps latency

Hello all,

I have an issue where we have a 10gbps backbone, and our blade chassis
are also 10gbps however the actual blades themselves are only 1gbps.
This links are no where near saturated. Even the 10Gbps uplinks rarely
carry over 50Mbps of traffic.
We are having some performance issues with Oracle RAC, and the DB guys
are of course trying to blame the network. They are claiming that
upgrading the blades to 10Gbps will solve all our issues. I have
explained that we are not saturating the links, we are seeing no
discarding/queuing/etc, but they insist that we will see improvements
in latency by upgrading the blades. They are basing all of this
anecdotally on the fact that one of the DB developers ran into this
at his previous employer and that is how they solved it.

Most of the Cisco spec sheets I have found do show an improvement in
latency when comparing Multiple 1Gbps links to 10Gbps, but seem to
make the assumption that some of these links are saturated. This makes
sense, but what about in the absence of much traffic, is a 10Gbps link
"faster" than a 1Gbps link?

I remain unconvinced that it will make a bit of difference, but would
like to hear other opinions.

Thank you,

Marc

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Received on Mon Jul 11 2011 - 14:59:51 ART