I recently had a “stimulating discussion”* with Tom about MPIO initiated from a virtualized guest OS to a new SAN I am installing, and the pros and cons there of. This is one of those situations where the constraints of the technology make sense in a physical situation, but look a bit odd virtualized, so I wanted to ensure that I had the best possible solution for my needs, with the least extra effort, and importantly, some logic to back up the decision.
On MPIO and In-Guest iSCSI
When IIS ‘Configure’ Files Truncate
Not so common problems
There is a subset of problems that happen very very rarely. That require a set of coincidences to occur in order for them to happen. The chances of these events actually happening are so small as to be negligible. In modern computing, they happen.
Queued Exchange Mailbox Moves
This morning I had a list of Exchange 2010 move requests that were sat in a queued state. None in progress, but a few complete. So what was holding them up?
First I tried suspending/resuming them:
Get-MoveRequest -multitenant | suspend-moverequest -Confirm:$false
Get-MoveRequest -multitenant | resume-moverequest
That didn't help.
Next I tried removing and re-creating the requests:
[PS] C:\scripts>Get-MoveRequest -MultiTenant | Get-MoveRequestStatistics | select displayname,exchangeguid,targetdatabase | export-csv moves.csv
[PS] C:\scripts>Get-MoveRequest -MultiTenant | Remove-MoveRequest -Confirm:$false
[PS] C:\scripts>Import-Csv .\moves.csv |foreach-object {new-moverequest -confirm:$false -Identity $_.Exchangeguid -targetdatabase $_.Targetdatabase}
But still no dice. The next thing I noticed though was that the moves were all targeted at databases on the same server, so I went hunting services on that machine. It turns out that the "Microsoft Exchange Replication" service was stopped. Kicked that into action, and bingo, 4 moves went to "In Progress"
How I nearly failed (part of) the CCNA again
A Little Bit of History
CCNA for me has been a long journey. I first saw the cert 8 or 9 years ago, and I've always fancied giving it a go, but never had the opportunity until my current role. I've managed to fail the combined CCNA exam twice so far, at my employers expense, and took a break to get some of the Microsoft Windows Server 2012 certs under my belt to keep us in line with Partnership levels. Now I'm back to the CCNA in earnest.
This time I decided to go for the two separate. There are a couple of reasons for this, some financial ones, but the biggest driving force was to keep things as simple as possible. There is no getting away from the fact that the CCNA exams try you. I'm not in a position where I access switches every day, my role is further up the stack, so although I have plenty of experience on switches, setup and config happens with big gaps between, and lots of copying from existing configs and Google. I under estimated the combined exam the first time, and was just not properly prepared.
Exam Day Dawns
The night before the exam was spent in a data center fixing critical issues, rather than studying and getting a good nights sleep, that didn't bode well, and put me in entirely the wrong frame of mind. The exam center I was booked into is one I've never been to before, in a town I don't know well, and the route turned out to be covered in roadworks. At one point I actually ended up going the wrong way down a bus lane! I gave myself half an hour longer to get there than I needed, and I still used every single minute.
So to say when I sat down I was a little bit agitated would be a massive understatement! I've always been told to get a good sleep the night before exams, and to get there in plenty of time. That is very good advice.
The Paper Itself
The exam was exactly what I've come to expect from Microsoft and Cisco exams in the past, a bit of pre-amble and disclaimers, then the exam proper. One habit I've come to over the past few months is to use some of the pre-amble time to make some notes from memory to refer to during the exam. In particular for ICND1, I wrote down the slash notation, dotted decimal, and number of hosts per subnet of the various subnets from 22 to 32. This is useful because it means I don't have to do the calculations during the exam, I can just quickly scan down the table. In both the CCNA and the ICND1 exams a lot of questions involve working out subnets, and number of hosts per subnet before you can actually answer the question itself. This is stuff that it's absolutely vital to know.
One thing to bear in mind with Cisco exams, that's different to MS ones, is that with Cisco, there is no going back. Once a question is answered, that's it, there is no review option.
The final Question
I always find hitting next on the final question a heart in mouth moment. There really is nothing else for it, but pressing the button and seeing the result is like the moment before you pull a plaster, will it be good news or bad? This time it was even worse. I hit next, and the exam application crashed! Were all my answers lost? Invalid? Was the result corrupted? Would I have to wait for the exam to be manually checked? All of these things flashed through my head in the moments before I informed the invigilator.
Fortunately for me, everything was fine. The errors were recorded, and the app restarted, and it picked up exactly where I'd left off. One last answer to fill in, and click next. With even more trepidation than usual I clicked the fateful button. I was greeted by a "Congratulations" screen, and I breathed a huge sigh of relief. I passed, by the skin of my teeth, I passed
Final Thoughts
So what have I learned from this? Well, firstly I should book exams for when I'm not on call. The late night, and vitally, no last revision night was a killer. I wasn't in a good place to sit the exam, but at that point, I was committed. I could have avoided that pain with a little thought.
Secondly, I should have done a drive by of the exam center. Juggling GPS and road works to find a small building in a city center isn't easy, especially in rush hour. Again, a bit of prep and I wouldn't have had any problems.
Finally, the separate exams are a really good option. Even though I've been working with this stuff for years, I've only ever done what's needed for my networks, so there are huge chunks of the exam I've never needed in earnest or plain passed over. Unless you have plenty of free time running up to the exam to devote to study, breaking the content up gives you a much better chance of having the depth of knowledge required.
Now, onto ICND2...
Centos and VMware tools
I found a funky blog post detailing the steps to get VMware tools from the official vmware repo. The details below are for 4.1 but it should be easy enough to tweak for other versions of ESX...
Add VMware GPG keys:
rpm --import http://packages.vmware.com/tools/keys/VMWARE-PACKAGING-GPG-DSA-KEY.pub rpm --import http://packages.vmware.com/tools/keys/VMWARE-PACKAGING-GPG-RSA-KEY.pubEdit /etc/yum.repos.d/vmware-tools.repo:
[vmware-tools] name=VMware Tools baseurl=http://packages.vmware.com/tools/esx/4.1latest/rhel6/$basearch enabled=1 gpgcheck=1Install VMware Tools:
yum install vmware-open-vm-tools-nox