Monday, April 29, 2013

DELL PowerConnect Time Configuration


Here is procedure how to setup it:

enable
configure
sntp unicast client enable
sntp server ntp.cesnet.cz
end

Here is how to verify:


console#show sntp configuration

Polling interval: 64 seconds
MD5 Authentication keys:
Authentication is not required for synchronization.
Trusted keys:
No trusted keys.
Unicast clients: Enable

Unicast servers:
Server          Key             Polling         Priority
---------       -----------     -----------     ----------
195.113.144.201 Disabled        Enabled         1
195.113.144.204 Disabled        Enabled         1

Here is how to check current time:


console#show clock

10:23:42 (UTC+0:00) Apr 29 2013
Time source is SNTP

Summary:
That's how to set time on DELL PowerConnect switches. Please note that time is in UTC +0:00 so when you want localize your time you can use "clock timezone" and "clock summer-time" command in conf mode but I don't like it. UTC time is better for troubleshooting.  



Tuesday, April 16, 2013

Network Overlays vs. Network Virtualization

Scott Lowe published very nice blog post (philosophy reflection) about "Network Overlays vs. Network Virtualization".

And this was my comment to his post ..

Scott, excellent write-up. As always. First of all I absolutely agree that good definitions, terminology, and conceptual view of particular layer is fundamental to fully understand any technology or system. Modern hardware infrastructure is complex and complexity is growing year on year.
Software programming has the same history. Who programs in assembler nowadays? Why we use object oriented programming more then 20 years? The answer is ... to avoid complexity and have control on system behavior. In software MVC model is often use and it stands for Model-View-Controller. Model is logical representation of something we want to run in software, View is simplified model presentation to end user and controller is engine behind the scene. The same concept apply to SDI (Software Defined Infrastructure) where SDN (Software Defined Network) is another example of the same story.
VMware did excellent job with infrastructure abstraction. Everything in VMware vSphere is object. Better to say managed object which has some properties and methods. So it is the model. vSphere Client or Web Client or vCLI or PowerCLI are different user interfaces into the system. So it is View. And who is Controller? Controller is vCenter because it orchestrates system behavior. vCenter controller includes prepackaged behavior (out-of-the-box) but it can be extended by custom scripts and orchestrated externally for example by vCenter Orchestrator. That's what I really love VMware vSphere. And it is from the begining architected to purely represent hardware infrastructure in software constructs.
Now back to Network Virtualization. In my opinion Network Overlay (for example VXLAN) is mandatory  component to abstract L2 from physical switches and have it in software. Particular Network overlay protocol must be implemented in "Network Hypervisor" which is software L2 switch. But "Network Hypervisor" has to implement also other protocols and components to be classified as "Network Virtualization" and not only as just another software vSwitch.
What Scott already mentioned in his post is that networking is not just L2 but also L3-7 network services so all network services must be available to speak about full "Network Virtualization". Am I correct Scott? And I feel the open question in this post ... who is the controller of "Network Virtualization"? :-)  

Monday, April 15, 2013

Tecomat: Industrial and home automation

Perl script to get Managed Object ID from vSphere

If you've already scripted vSphere infrastructure you probably already know that everything has software representation also known as Managed Object. Each Managed Object has unique identifier referenced as Managed Object ID. Sometimes this Managed Object ID is needed so here is perl script leveraging VMware vSphere Perl SDK to get Managed Object ID for particular virtual machine or datastore. If you need MOID for another entity it's pretty easy to slightly change the script bellow.

Script is developed and tested on vMA (VMware management Assistant) in directory /usr/lib/vmware-vcli/apps/general and script name is getmoid.pl

Here is usage example how to get MOID of datastore called FreeNAS-iSCSI-01:
./getmoid.pl --server --username --password --dsname FreeNAS-iSCSI-01

Manage Object ID: datastore-162



Here is usage example how to get MOID of virtual machine called VMA:
./getmoid.pl --server --username --password --vmname VMA
Manage Object ID: vm-122


Any feedback or comments are welcome.

Monday, April 08, 2013

How to create FreeBSD memstick in running FreeBSD system

# make 2GB image file: dd if=/dev/zero of=./memstick.img bs=1m count=2000 # load image as virtual disk device: mdconfig -a -t vnode -f ./memstick.img -u 0 fdisk -iI /dev/md0 bsdlabel -wB /dev/md0s1 newfs /dev/md0s1a mount /dev/md0s1a /mnt cd /usr/src make installkernel installworld DESTDIR=/mnt umount /mnt # insert memstick now, assuming it will be /dev/da0... # raw copy virtual disk content to memstick. dd if=/dev/md0 of=/dev/da0 bs=1m