The Unified Computing Blog
Everything related to Cisco's Unified Computing System
Placement of mezzanine adapters in full width blades
Jul 5th
During a discussion recently with some other UCS-savvy folks, I realized that there may be some confusion in how to place mezzanine adapters in full width blades when you’re only using one adapter.
First, a quick review of how UCS pins mezzanine ports to uplinks. I’ll skip the one uplink option, since all ports use the single uplink.
In a two-uplink configuration, all odd numbered slots use uplink #1, while all even numbered slots use uplink #2. (Easy to remember – odds go to the odd uplink, evens go to the even uplnk). Since a full-width blade occupies two horizontally More >
Chassis Discovery Policies in UCS
Jun 20th
Cisco UCS provides a configurable “Chassis Discovery Policy” that affects how chassis links (called “Server Ports”) are activated when discovering a new chassis. See this page on cisco.com.
After a recent discussion on Twitter, I decided to test out a few scenarios.
My configuration is a pair of UCS 6120 Fabric Interconnects, two UCS 5108 Chassis, with 2 links per IO Module.
Additionally, this particular lab is on a reasonably old version of UCSM code, 1.0(1f). I’m not in a position to upgrade it at the moment – I can re-test at a later date with more current code. I don’t expect More >
The Problem With Vendor Sponsored Testing
Jun 16th
I suppose this post has been a long time coming.
It was spurred into reality by an exchange with @bladeguy who pointed out that Cisco, too, sponsors tests of their equipment – just like HP and the Tolly reports. At first, I’d intended to do a comparison of the Tolly reports and the Principled Technologies reports, looking for obvious (or not so obvious) bias. Once I started down that path, however, I realized it really wasn’t necessary. Sponsored tests (from any organization) will always be biased, and therefore unreliable from a technical perspective. There are always tuning parameters that the “loser” More >
Private Isolated VSANs?
Jun 13th
Ok, so this isn’t really UCS related. Just a random thought I had today while working on a lab project… why don’t we have Private VSANs? As in, the same type of technology as Private VLANs (PVLANs)?
First, some background. Standard SAN best practice for access control is to use single-initiator/single-target zoning. This means that there’s one zone for each combination of host and storage, tape, virtualization platform, etc port. Some administrators think this is overkill, and create just a few zones of lots of initiators to single targets, but this is overall a bad idea. The purpose of this post More >
UCSM 1.3(1c) Released!
Jun 11th
Cisco has released UCS Manager version 1.3(1c). This is the first public release in the 1.3 line, also known as “Aptos+”.
Release notes are here: http://www.cisco.com/en/US/docs/unified_computing/ucs/release/notes/ucs_22863.html
Haven’t gotten a chance to play with the new version yet, but there are some significant enhancements. Among them…
- 1 GE support on UCS6120 and UCS6140 Fabric Interconnects
- On the 6120, you can now use 1GE transceivers in the first 8 physical ports.
- On the 6140, you can now use 1GE transceivers in the first 16 physical ports.
- Watch for a post soon on why I think this is a bad idea.
- Support for the new, 2nd generation mezzanine More >
Correction to L2 Forwarding Rules post
Jun 7th
I posted here about the L2 forwarding rules when UCS is in EHV mode. Several readers have pointed out a flaw in the logic I posted, which was taken from Cisco’s DCUCI course. In Cisco’s defense, I did write that course.
At issue is how UCS deals with unknown unicast frames. The other post incorrectly states than an unknown unicast frame received from a server port would be flooded out all other server ports participating in the same VLAN. This is not the case.
The logic behind EHV mode is that it is impossible to have an More >
Cisco Press book on UCS now shipping!
Jun 7th
Got notification today from Amazon that the new Cisco Press book on UCS by Silvano Gai, Tommy Salli, and Richard Andersson is now shipping. Take a look, it’s in my UCS Bookstore.
Great UCS write-up by Joe Onisick
May 23rd
If you’re not currently following Joe’s blog over at definethecloud.wordpress.com, you should start.
He just posted another great article on why UCS is his server platform of choice. Before you write him off as just another Cisco fan-boy, definitely take a look at his logic. Even if you have another vendor preference, he presents some excellent points to consider.
Take a look : http://definethecloud.wordpress.com/2010/05/23/why-cisco-ucs-is-my-a-game-server-architecture/
UCS with disjointed L2 Domains
May 8th
How do we deal with disjointed L2 domains in UCS?
To start, what’s a disjointed L2 domain? This is where you have two Ethernet “clouds” that never connect, but must be accessed by the same UCS Fabric Interconnect. Take, for example, a multi-tenant scenario where we have multiple customer’s servers within the same UCS cluster that must access different L2 domains.
How do we ensure that all traffic from Customer A’s blade only goes to their cloud, while Customer B’s blades only connect to their cloud?
The immediately obvious answer is to use UCS pin groups to tie each customers interfaces (through More >
UCS Bookstore
Apr 20th
Since my previous announcements about various books on UCS and related topics have gotten rolled off the main page, I thought it would be useful to collect them into a bookstore. I’ve added a link (see the navigation tabs at the top of the screen) to my UCS Bookstore. Feel free to have a look, and make any suggestions on books you think should be included.
Defining VN-Link
Apr 19th
The misunderstanding of Cisco’s enhanced network products for VMware environments has hit critical mass. At this point very few people know what does what, how, and when to use it. Hopefully this will demystify some of it.
VN-Link:
Product name for a family of products, does not specifically refer to any one product so forget the idea of hardware vs. software implementation, etc. Think of the Nexus family of switches: 1000v, 2000, 4000, 5000, 7000. All different products solving different design goals but are components of the Data Center 3.0 portfolio. The separate products that fall under VN-Link are described below:
Nexus 1000v:
The More >
Updated 10GE Transceiver Support Matrix
Apr 19th
Cisco posted an updated 10GE transceiver compatibility matrix on April 7. Unfortunately, the 7M SFP+ cables from Panduit (or any TwinAx cables from Panduit, for that matter) aren’t on it. Well, let’s continue to hope…
8Gb Fibre Channel or 10Gb Ethernet w/ FCoE?
Apr 8th
Which is better? Which is faster?
I’ve been stuck on this one for a while. I’m traditionally a pure fibre channel kind of guy, so I’ve been pretty convinced that traditional FC was here to stay for a while, and that FCoE – as much as I believe in the technology – would probably be limited to the access and aggregation layers for the near term. That is, until it was pointed out to me the encoding mechanisms used by these two technologies and the effective data rates they allowed. I’m not sure why it never occurred to me before, but More >
Fantastic post on statelessness : HP VirtualConnect vs. Cisco UCS
Apr 6th
M. Sean McGee posted this great comparison of VirtualConnect and UCS. I’ve often struggled to give students a clear picture of the differences – HP will tell you that “VirtualConnect is just as good, and we’ve been doing it for years!”. Well, yes… it does some things similarly, and you can’t argue the timeframe. UCS does a lot more – and until now, I didn’t have a great source that directly compared them. From now on, all I have to do is send them to M. Sean McGee’s post!
UCS Manager 1.2(1) Released
Mar 29th
As a full UCS bundle (including all code – from the lowliest baseboard management controller to the UCS Manager in all it’s process-preserving glory), Cisco has released version 1.2(1).
Full release notes are available here.
To summarize, this release adds support for the soon-to-be-shipping “M2″ versions of the UCS blades, which support the Intel Xeon 5600-series processors (Westmere), which include the 6-core version of the Nehalem lineage. There are also numerous bug-fixes (expected in this generation of product), including many on my list of “slightly annoying but still ought to be fixed” bugs.
Panduit Completes 7 Meter SFP+ Copper Cables!
Mar 25th
Panduit is now shipping their 7 meter SFP+ copper twinax cables. They’re not officially on the Cisco compatibility list yet, but once they are, this opens up some additional UCS expansion options. The jump from 5 meter to 7 meter may not seem like a lot, but that’s another rack and a couple of more chassis… who couldn’t use another 32 or 48 blades while still keeping the cabling infrastructure cheap?
My understanding is that the cables work just fine in UCS and Nexus 5000 configurations, but aren’t yet officially supported by Cisco.
Cloud Computing Blog
Mar 12th
Joe Onisick, Firefly Communications‘ CTO in EMEA has started a blog on cloud computing. Good stuff, check it out:
Define The Cloud – http://definethecloud.wordpress.com/
L2 Forwarding Rules in UCS EHV Mode
Mar 1st
After a recent comment from @robertquast, it occurred to me that there’s quite a bit of confusion about the way that UCS Fabric Interconnects handle layer-2 forwarding in the default and recommended Ethernet Host Virtualizer mode.
The basic idea behind EHV is that the Fabric Interconnect appears to the upstream network as if it were a host and not a layer-2 switch. To accomplish this (and not require our old friend Spanning Tree Protocol), the Fabric Interconnect employs a number of L2 forwarding rules and deja vu checks to prevent the creation of L2 loops. If you know how VMware vSwitches More >
Tolly Report
Feb 28th
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 More >
MAC forwarding table aging on UCS 6100 Fabric Interconnects
Feb 22nd
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 More >