A lot of people have been asking me what I think of the recently released Tolly report comparing the bandwidth of the HP and Cisco blade solutions.
The short answer is, I don’t think much of it. It’s technically sound, and the the conclusions it reaches are perfectly reasonable – for the conditions of the tests they performed. In keeping with Tolly’s charter, the tests were repeatable, documented, and indisputable. The problem is, the results of the testing only tell half the story. The *conclusions* they reach, on the other hand, aren’t as defensible.
It’s really not necessary to get into a point by point rebuttal. At least not for me. I’m sure Cisco will be along any minute to do just that.
The facts that Tolly established during the report aren’t groundbreaking or surprising. Essentially, the tests were built to demonstrate the oversubscription of links between UCS chassis and Fabric Interconnects, which Cisco is quite willing to disclose at 2:1. These tests were paired with HP comparisons of blade-to-blade traffic on the same VLAN, which in HP architectures keeps the traffic local to the chassis. The interesting thing there is that if the traffic were between the same blades but in different VLANs, the Cisco and HP solutions would have performed identically (assuming the same aggregation-layer architecture). What makes that interesting is that the Tolly report’s figures depend on a specific configuration and test scenario – the Cisco values won’t change (or get any worse) no matter how you change the variables. The HP values will vary widely.
And that, my friends, is where I see the true benefit of Cisco’s architecture. Change the conditions of the test repeatedly, and you’ll get the same results.
I’m not faulting Tolly in this case. Not at all. They were asked to test a certain set of conditions, and did so thoroughly and presumably accurately. It’s just that you can’t take that set of data and use it to make any kind of useful comparison between the platforms. The real world is much more complicated than a strictly controlled set of test objectives. Do we really think that HP went to Tolly and asked “We want a fair fight?” Of course not.
I was recently forwarded some information on the MAC table aging process in the UCS 6100 Fabric Interconnects that I thought was very valuable to share.
Prior to this information, I was under the impression (and various documentation had confirmed) that the Fabric Interconnect never ages MAC addresses – in other words, it understands where all the MAC addresses are within the chassis/blades, and therefore has no need to age-out addresses. In the preferred Ethernet Host Virtualizer mode, it also doesn’t learn any addresses from the uplinks, again, so no need to age a MAC address.
So what about VMware and the virtual MAC addresses that live behind the physical NICs on the blades?
Well, as it turns out, the Fabric Interconnects do age addresses, just not those assigned by UCS Manager to a physical NIC (or a vNIC on a Virtual Interface Card – aka Palo).
On UCS code releases prior to 1.1, learned address age out in 7200 seconds (120 minutes) and is not configurable.
On UCS code releases of 1.1 and later, learned addresses age out in 7200 seconds (120 minutes) by default, but can be adjusted in the LAN Uplinks Manager within UCS Manager.
Why do we care? Well, it’s possible that if a VM (from which we’ve learned an address) has gone silent for whatever reason, we may end up purging it’s address from the forwarding table after 120 minutes… which will mean it’s unreachable from the outside world, since we’ll drop any frame that arrives on an uplink to an unknown unicast MAC address. Only if the VM generates some outbound traffic will we re-learn the address and be able to accept traffic on the uplinks for it.
So if you have silent VMs and have trouble reaching them from the outside world, you’ll want to upgrade to the latest UCS code release and adjust the MAC aging timeout to something very high (or possibly never).
@SlackerUK on Twitter asked about moving Service Profiles between UCS clusters.
In short, it’s not currently possible with UCS Manager without a bit of manual work.
First, create a “logical” backup from UCS Manager. This will create an XML file containing all of the logical configuration of UCS Manager, including your service profiles. Find the service profile you want, and remove everything else from the backup. You can then import that XML file into another UCS Manager instance. Be aware that everything comes with that XML, including identifiers – so make sure you’re OK with that or remove the original service profile to eliminate duplicates.
If you’re using BMC Bladelogic for Cisco UCS, it *does* have the capability to move service profiles between clusters.
Well, it’s official. HP is not going to be a Cisco gold partner any longer.
Given HP and Cisco’s very public competition, I can’t say this is any surprise. While HP certainly has contributed significant sales to Cisco in the past in the form of routing and switching equipment, HP has aggressively moved to position their own products in front of Cisco’s recently (and why wouldn’t they?).
Does anyone think this actually means much for the sales of either company, or more of a “yawn” type move?
Full Story Here
In order to allow for granular security control, UCS Manager allows you to disable individual services and protocols, in accordance with your policies or security goals.
Since HTTP/HTTPS are the primary methods of administering the system, and the command line is *not* a standard IOS or NXOS, how do you re-enable these protocols if they are inadvertently disabled?
Luckily for me, I got to test this out in a recent class. 🙂
Gain access to the UCS Manager CLI, either through SSH/Telnet (if still enabled) or through the serial console. Because all configuration options are stored as objects in the UCS Manager database, we need to adjust our scope to the SystemServices layer.
ucsm-A # scope system
ucsm-A /system # scope services
ucsm-A /system/services # enable ?
cimxml Cimxml service
http HTTP service
https HTTPS service
telnet-server Telnet service
ucsm-A /system/services # enable http
ucsm-A /system/services # enable https
ucsm-A /system/services #
That’s it… welcome back. 🙂