My ramblings on the stuff that holds it all together
Category Archives: Virtual Switches
In the lab I am currently working with I have a set of vSphere 4 ESXi installations running as a virtual machine and configured in an HA cluster – this is a great setup for testing VM patches, and general ops procedures or learning about VMware HA/DRS/FT etc. (this lab is running on a pair of ML115 g5 servers but would work equally on just one
Everything installed ok and I can ping the virtual ESX servers from the vCenter host that manages the cluster (the warning triangle is that there is no management network redundancy – I can live with that in this lab.
All ESX hosts (physical and virtual) are connected via iSCSI to a machine running OpenFiler and the storage networking works ok, however when I configure the vMotion & FT private networks between the VM ESX hosts I cannot ping the vMotion/FT IP addresses using vmkping – indicating that there were some communication problems, normally this would be a VLAN issue or some routing but in this instance all the NICs and IP addresses for my lab reside on a flat 10.0.0.0/8 network (it’s not production, just a lab).
After some digging I came across this post for running ESX full as a VM, and noted the section on setting the vSwitch to promiscuous mode so I tried that with the vSwitch on the physical ESX host that the two ESXi VMs were running on;
And now the two Virtual ESXi nodes can communicate via vmkping
Problem solved and I can now vMotion nested VMs between each virtual ESX host – very clever!
As noted here there is a doc that has been jointly produced between VMWare and Cisco which has all the details required for integrating VI virtual switches with physical switching.
Especially handy if you need to work with networking teams to make sure things are configured correctly to allow failover properly between redundant switches/fabrics etc. – it’s not as simple as it looks, and people often forget the switch-side configurations that are required.
Doc available here (c.3Mb PDF)
Note to remember, don’t forget to check the duplex settings on NICs handling your vMotion traffic.
My updated clustered ESX test lab is progressing (more posts on that in the next week or so)… and I’m kind of limited in that I only have an old 24-port 100Mb Cisco hub for the networking at the moment.
vMotion warns about the switch speed as a possible issue.
I had my Service Console/ vMotion NICit forced to 100/full and when I 1st tried it vMotion took 2hrs to get to 10%, I changed it to auto-negotiate whilst the task was running and it completed without breaking the vMotion task ain a couple of seconds, dropped only 1 ping to the VM I moved.
Cool, it’s not production or doing a lot of workload but useful to know despite the warning it will work even if you’ve only got an old hub for your networking, and worth remembering that Duplex mis-matches can literally add hours and days onto network transfers.
Doc from Cisco Here.
Interesting article here on how Cisco have made heavy use of virtualization within their new ASR series router platform, Linux underneath and 40 core CPUs!
This type of approach does make me wonder if we will get to the stage of running traditional “network” and “storage” services as VM’s under a shared hypervisor with traditional “servers”.. totally removing the dependency on dedicated or expensive single-vendor hardware.
Commodity server blade platforms like the HP or Sun blade systems are so powerful these days, with flexible interconnect/expansion options this type of approach makes a lot of sense to me and is totally flexible.
Maybe one day it will go the other way and all your Windows boxen will run inside a Cisco NX7000 lol!
On reflection maybe all those companies have too much of a vested interest in vendor lock-in and hardware sales to make this a reality!
There’s an interesting post over on Forrester research blog by James Staten. he’s talking some more about data centres in a container; making the data centre the FRU rather than a server or server components (Disk, PSU etc.).
This isn’t a new idea but it I’m sure the economics of scale currently mean this is currently suitable for the computing super-powers (Google, Microsoft – MS are buying them now!) – variances in local power/comms cost could soon force companies to adopt this approach rather than be tied to a local/national utility company and their power/comms pricing.
But just think if you are a large out-sourcing type company you typically reserve, build and populate data centres based on customer load, now this load can be variable; customers come and go (as much as you would like to keep them long-term this is becoming a commodity market and customer’s demand you are able to react quickly to changes in THEIR business model – which is typically why they outsource – they make it YOUR problem to service their needs).
It would make sense if you could dynamically grow and shrink your compute/hosting facility based on customer demand in this space – thats not so easy to do with a physical location as you are tied to it in terms of power availability/cost and lease period.
New suite build out at a typical co-lo company can take 1-2 months to establish networking, racks, power distribution, cabling, operational procedures etc. (and that’s not including physical construction if it’s a new building) – adopting the blackbox approach could significantly reduce the start-up time and increase your operational flexibility
Rather than invest in in-suite structured cabling, rack and reusable (or dedicated) server/blade infrastructures why not just have terminated power, comms and cooling connections and plug them in as required within a secured warehouse like space.
You could even lease datacentre containers from a service provider/supplier to ensure there is no cap-ex investment required to host customers.
If your shiny new data centre is runs out of power then you could relocate it a lot easier (and cheaply) as it’s already transportable rather than tied to the physical building infrastructure; you are able to follow the cheapest power and comms – nationally or even globally.
As I’ve said before the more you virtualize the contents of your datacentre the less you care about what physical kit it runs on… you essentially reserve power from a flexible compute/storage/network “grid” – and that could be anything/anywhere.