This is quite amazing: A guy called David Gilday has built a Lego Mindstorms NXT robot that solves a 4×4x4 Rubik’s Cube (way harder than a 3×3x3), but the twist is: the real brains of the operation is a Nokia N95 that actually scans the cube with its camera, figures out how to solve it and then tells the robot what moves to make. Very, very cool David, you have officially too much time on your hands 
Source: Make
Recently I passed my VMware VCP 3 and VPC 4 exams (i.e.: VMware Certified Professional on versions 3 and 4), which to be honest felt kind of odd as I’ve been doing things with VMware way beyond these certifications’ standards for quite a while…which leads me to ponder the normal IT certifications as a whole.
An example from the past: I’d been managing Windows networks and servers since 1995-ish but never got any sort of certification, until I got my MCSA and MCSE (Microsoft Certified Systems Administrator and -Engineer respectively) in 2002, basically because my employer demanded it of me. Not a problem, hit the books at home, do some test exams followed by the actual exam and hey presto, certified. In 2007 my current employer asked me to upgrade my Windows 2000 MCSA and MCSE to Windows 2003. Once again, books – test exam – exam – bingo.
In both of these cases the books and exams tought me nothing new, nor showed me any aspect of the OS and its functions that surprised me or that I hadn’t worked with before, so the certifications at the time felt like ‘an extra piece of paper’.
The big question that arises of course is: are these certifications of any real use? In my opinion, if the exams (or the books prepping you for the exams) teach you anything really new you’re not really ready to be a certified anything. On the other hand, if it’s all easy and old hat for you, what is the point of getting the certification aside from adding to your C.V., as you’re already fully versed in the actual subject matter?
Most of the time IT geeks must pass certain exams to keep their employers on a certain partnership level with the company in question, for example Microsoft demands (among other things) a certain number of certified engineers at a company for them to accept your company as a “Microsoft Certified Partner” at any particular level (which, to be honest, does have some advantages such as access to NFR software to play around with, extra internal-use licenses, some business tools for selling and marketing their stuff and of course a slightly lower purchase price for their products, increasing revenue).
All well and good, but what’s in it for me? Do my certifications really make my C.V. stand out in the crowd when looking for a job? Or is it just a minimum-level-marker so the prospective employer is assured he’s not getting a complete dolt? I personally think it depends on the actual certifications, and (prospective) employers should be aware of what is actually demanded from people to get certain certifications. Example: Microsoft’s MCSA, and in some cases MCSE, exams could have been passed by someone with a good memory for test questions but with no actual work experience with the prodcuts, whereas Cisco’s exams try to weed out the ‘book smart’ people by posing actual issues to solve. Thus, just relying on a person’s list of acronyms is not enough, you do have to invest some time in figuring out what the certifications really mean, and in any case: there is never any substitution for actual work experience.
For me, I’ll probably stick with the way I’ve been doing it now. Really get to know the products and technologies I work with, and take the exam when I feel comfortable I could pass it without opening a single book beforehand, with the possible exception of an exam guide to prep me for the exam itself.
Yes, very techie, but choosing RAID levels is always a bit of a process to find the right level or combination of levels. Today I had to do another analysis and make the choice, and while checking my data I found this great write-up: Difference between RAID 0+1 vs RAID 1+0 by Decypher Information Systems. Clear, to the point and well written.
I’ve built and actively manage a number of VMware ESX servers and server clusters, and one of the things that bug me is that as soon as I delete a snapshot I have no idea on its progress (especially if it’s a large snapshot, which can take quite a while).
Here’s a quick tip to keep an eye on the snapshot deletion: Once you’ve given the command to delete a snapshot, go to the CLI (i.e.: log in to the ESX server that the VM is on), then cd to the directory where the VM is located:
cd /vmfs/volumes/DatastoreName/VMname
Once in the directory use the command:
file *
This will give you an extended list of the files in that directory. The files that the snapshot process is working on will be listed as ‘can’t read ‘diskfilename.vmdk’ (Device or resource busy)‘. Now you can check that these are both the snapshots and the main disks that the snapshot data is to be committed to. To see if the process is actually writing to the target disk file, just ls it every so often and keen an eye on the date and time, it should update to indicate that the disk image is being written to.
A short example: Say the VM is called ‘VMSERVER01′ and it’s on a datastore called ‘SANvolume1′. You use the Snapshot Manager in the VI Client to delete a snapshot, then SSH to the ESX server.
cd /vmfs/volumes/SANvolume1/VMSERVER01
file *
The result would look something like this:
VMSERVER01-flat.vmdk: can't read 'VMSERVER01-flat.vmdk' (Device or resource busy).
VMSERVER01.vmdk: ASCII English text
VMSERVER01-d1e733fe.hlog: ASCII text
VMSERVER01-d1e733fe.vswp: empty
VMSERVER01-000001-delta.vmdk: can't read 'VMSERVER01-000001-delta.vmdk' (Device or resource busy).
VMSERVER01-000001.vmdk: ASCII English text
VMSERVER01.nvram: VMware nvram
VMSERVER01.vmsd: ASCII text
VMSERVER01.vmx: a /usr/bin/vmware script text executable
VMSERVER01.vmxf: XML document text
vmware.log: ASCII C++ program text, with very long lines
This shows you that the server is busy committing the data from the snapshot file (VMSERVER01-000001-delta.vmdk) to the main disk file (VMSERVER01-flat.vmdk). Now you know which disk file should be the one being written to so you can just use ls every once in a while, while the server is still busily chewing on the snapshot, to see the time on the main disk file change to confirm that is is still being written to:
ls -l VMSERVER01-flat.vmdk
Every once in a while also run the file command again to se whether or not the snapshot files have disappeared, confirming that the snapshot has indeed been deleted.
Hope this helps, it did for me
Suppose you have a network with multiple VLANs, each with its own subnet, and you want your DHCP server(s) to serve addresses and configuration to all subnets (or at least more than one of them). The problem normally is that broadcast traffic (such as DHCP requests from clients) cannot traverse broadcast domains, which is exactly what VLAN separation does: limit broadcast domains.
There’s basically three solutions: the first is to provide a single DHCP server with a network interface in each VLAN. This will work fine for a very limited number of VLANs, but is not very effective for larger numbers of VLANs and it’s also not very flexible. Every new VLAN requires an extra NIC, cabling, etc.
The second solution is to provide each VLAN with its own DHCP server. This is not very flexible either and eats lots of resources per VLAN and adds a lot of management complexity.
The third solution adds flexibility, ease of management and does not require a major investment in separate servers. What you do need however is a Layer3 switch in stead of a Layer2 model. The reason for this is that the switch has to be capable to route, or more accurately: re-route IP packets.
To enable a single DHCP server to serve multiple subnets, one per VLAN, you can configure your switch (both Cisco and HP Layer3 switches can do this, and probably most other brands as well) with an ‘IP helper’. An IP helper address tells the switch to forward certain types of broadcasts (like DHCP requests, TFTP requests and DNS requests) via unicast to the IP address(es) configured. An example:
Here the DHCP server is using address 10.0.1.5 in VLAN 1, on subnet 10.0.1.0 /24. The two clients are on separate VLANs 2 and 3 with subnets 10.0.2.0 /24 and 10.0.3.0 /24 respectively. In this case, we need the switch that receives the DHCP requests broadcast from the clients to forward the requests to the DHCP server. To do this, we add the IP address of the server to the different VLAN interfaces as the IP helper:
interface vlan 1 ip address 10.0.1.1 255.255.255.0 interface vlan 2 ip address 10.0.2.1 255.255.255.0 ip helper-address 10.0.1.5 interface vlan 3 ip address 10.0.3.1 255.255.255.0 ip helper-address 10.0.1.5
The switch will now forward the request broadcasts to the DHCP server. If the DHCP server has been configured with separate ranges for each subnet, the right answer will be sent back by it to the switch and then forwarded to the client.
I went to hear Carlos Solari speak here in The Netherlands last week, and his message makes a lot of sense: to create truly secure infrastructures, devices and services, all components must be built using the ‘SBD’ or Security By Design principles.
Solari and his team put forth the view that to create a fully secure chain of trust (because trust is as important as security, if not more) the IT industry needs a verifiable, certifiable standard method of testing the eight factors they propose to enable manufacturers and developers to create truly secure products.
Aside from the solid message, Solari is a great speaker with an impressive career: the armed forces, then the FBI, followed by a couple of years as CIO for the Executive Office of the President at the White House. Now with Alcatel-Lucent’s Bell Labs as VP of security solutions, Carlos Solari is spreading the word on security, trust and reliability as inherent parts of any solution.
The book is “Security in a Web 2.0+ World: A Standards-Based Approach” and I recommend it. Amazon link here.
I took the ‘new’ Safari 4 out for a test spin today, and although I have absolutely no factual test data the page rendering was indeed as fast as promised. All in all Safari is a very clean and sleek browser and does handle all I can throw at it with ease (like big Flash content, old and new Java apps and even some huge Javascript stuff).
Having moved from IE to Mozilla some time ago I’m actually contemplating using Safari for my day-to-day browsing now. Me like.
Guido Jansen has written an interesting post on the (European) Open Source Network blog, entitled Ten Steps To a Killer App, a User Point-of-View. It’s not a technical treatise for coders but rather a good overview on everyting aside from the coding: how to make actually choosing, installing and using an app as easy as possible for a user. A very good read indeed.
Oh yes…you read that right: this video shows a demo of a Nokia N800 running VMware’s MVP (Mobile Virtualisation Platform), a hypervisor which virtualises the phone hardware, basically allowing you to run most any mobile device OS or more than one at once. In this demo the phone is running Windows CE and Android at the same time, while not limiting the functionality in any way.
Okay, technically the N800 is not a phone, but this technology is heading there fast. Very interesting, especially if both running OSes get full (shared) access to the actual comms hardware so you could for example run Android for your (GSM) phone functionality and Windows Mobile for the (3G) office connectivity at the same time.
The Cisco Nexus 1000V has been available for a while but I just realised I hadn’t raved about it yet, so here goes: it’s quite possibly one of the best examples of ‘technology A meets technology B and creates a beautiful baby’ I’ve seen in the past year.
The ‘normal’ Cisco Nexus series of switches are datacenter switches that can bully all lesser switches into handing over their lunch money, especially the flagship Nexus 7000 Series, whereas most VMware admins and engineers know that the basic vSwitches that are used inside VMware are cute but very limited, basically Corkies used to link the outside world to the VM world somewhat intelligently but with no real control.
Now Cisco has addressed this issue by giving us the Nexus 1000V: a fully functional virtual switch (read: vSwitch replacement) that provides the same flexibility and manageability we network geeks are used to from the Nexus and Catalyst model switches. Almost 100% the same command line, configuration options and tweakability that you’re used to, but geared completely to seamless integration with your VMware infrastructure. It’s a sweet package and a very well-deserved winner of the Best of VMware 2008 award in the “New Technologies” category. All that and it’s Vmotion-aware and -integrated as well.
As a both a (Cisco fanboy) network engineer but also a VMware engineer and admin I see this marriage as the start of something beautiful. Let’s hope Brocade is working on a fully functional Fibre Channel virtual switch to really get the party started!
Update (26-Feb): As noted in the comment from Cisco below: “availability is tied to the next upgrade to ESX from VMware. Our target is first half of 2009″. So, still some waiting to do…damn Thanks for the heads-up, Omar!
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