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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