Virtualization

Dell PowerEdge R610 & PERC/6i Disk Comparison

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I’ve recently done some very basic disk performance testing of a Dell PowerEdge R610 with 24 GB of RAM (1333 MHz), dual Intel X5550 CPUs, a PERC/6i RAID controller, and a bunch of 146 GB 15K RPM 2.5″ disks, as well as four of the Dell 50 GB enterprise SSD disks (which are Samsung drives). I tested various combinations of RAID 0, 1, 5, 6, 10, and 50 with 1, 2, 3, 4, and 6 disks. While the RAID controller configurations varied, all the configs had the element size set to 64 KB, read policy set to Adaptive Read Ahead, and write policy set to Write Back. The PERC/6i firmware was 6.2.0-013. The operating system was Red Hat Enterprise Linux …

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How To Submit Presentations To Conferences

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With the VMworld 2010 call for papers out there I’ve been thinking about judging submissions to conferences. I’ve been fortunate enough to have helped judge papers for a couple of conferences, and it’s been pretty educational for me. I’ve seen a lot of good submissions, but also a lot of rough ones, too. I’ve kept some notes about what I’m thinking when I judge a presentation and I thought maybe it would be helpful to others. 1. If your presentation is just whipped together please say so, up front. Ideally you’d have spent some quality time with your presentation and submitted it in an excellent, finished state, but we all know how deadlines sneak up on us. It’s just that …

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vSwitch vs. Nexus 1000V at TechTarget

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Rod Gabriel’s tweet clued me in that my latest work for TechTarget, VMware vSwitch vs. Cisco Nexus 1000V, is up, wherein the inimitable David Davis and I take opposing stances on VMware virtual networking. In true sysadmin form we’re both right and both wrong, of course, because it always depends on the situation, but I like the article.

Future Capacity Planning

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My favorite question from manager types is: “How many more VMs can we run before we have to expand?” I can never answer this without someone sticking it to me later. I always do end up answering it, and my answer is always wrong because it’s based on averages and the very little I’m told about future projects, upcoming P2Vs, server replacements, etc. We aren’t going to get 25 more 1.28 vCPU/2.398 GB of RAM VMs, though. It’s like having 1.75 kids — it just doesn’t work that way. I could try to tell them that we have 108 GB of RAM available, but that isn’t what they want, either. They want a concrete number they can multiply by our …

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WebEx & Aero

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WebEx and Microsoft Windows 7 don’t seem to get along 100% quite yet. If you are using WebEx on Windows 7 it’ll disable Aero during your session. However, if your session is over and you don’t get Aero back here’s how to fix it without rebooting: 1. Make sure you’ve closed/exited all WebEx components. 2. Right click on Windows Menu->All Programs -> Accessories -> Command Prompt and choose “Run as administrator.” You will need to accept a User Access Control warning about this. 3. Issue the commands: net stop uxsms net start uxsms That should fix it. Alternately (and potentially easier): you could restart the “Desktop Window Manager Session Manager” service via the Services administrative tool.

Rain Forecasted, From The Cloud, On Your Desk

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“I’m filling out a survey. Can you tell me if we have a cloud?” “Yes, we do,” I reply. “We do?” “Absolutely.” “Really?” “Yeah, I’d know — I built it.” “You built it? No, I think the survey wants to know if we have a real cloud.” Well, thanks a lot. “We do have a real cloud, and it’s the same one I’m talking about. In fact, we have two clouds, in two different locations. They’d probably be best described as ‘private clouds.’” “Well, there isn’t an option for private clouds, so I’ll just say no.” ARGGGH. Ten minutes pass… “Hey, I’ve got another question. Do we use virtualization software?”

Heisenberg & Monitoring

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From Wikipedia: In quantum mechanics, the Heisenberg uncertainty principle states that certain pairs of physical properties, like position and momentum, cannot both be known to arbitrary precision. That is, the more precisely one property is known, the less precisely the other can be known… The measurement of position necessarily disturbs a particle’s momentum, and vice versa. Stated a little more simply, the sheer act of measuring a particle disturbs it, such that you can only get approximate measurements. This is also true of computing systems and monitoring. The act of watching a system consumes resources on that system, which in turn skews the numbers you get from the monitoring system. The more data you collect, the more intensive the data …

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GoDaddy, SSL, and $13

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A GoDaddy representative left a comment on the post about ipsCA, saying: GoDaddy.com is happy to help ipsCA customers that have found themselves in a jam. For a limited time, our Standard SSLs are $12.99 with code sslqyh1w. Call 480-505-8877 or order online at http://bit.ly/91M3NV I’m not usually the kind of person to parrot an ad, especially one left on my site, but it’s actually a decent deal if you want a new, real SSL cert. Admittedly it’s not for their advanced certificates, but if you have a couple of ipsCA certs to replace it might work out just fine. Personally, I’ve been quite happy with GoDaddy as a domain registrar.

Linux Virtual Machine Tuning Guide Now Available

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It’s been a while in the making, but I finally started consolidating all my Linux VM tuning notes into a single document for all to read: Linux Virtual Machine Tuning Guide. Please take a look at it, and if there are corrections or additions to be made let me know. I know there is a lot to be done with network stack tuning, which will be added to a future revision when I get my notes sorted out.

How to Cancel a Stuck VMware Tools Install from the ESX CLI

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Q: I’m trying to evacuate a machine that is suffering a hardware failure, and one of the VMs thinks it is installing the VMware Tools, so it won’t VMotion. The error is “The virtual machine is installing VMware Tools and cannot initiate a migration operation.” I also cannot right-click the VM in vCenter and choose “End VMware Tools Install.” Is there a way for me to end the VMware Tools installation from the ESX command line? A: Yes, it’s a two-step process once you’ve logged into the console OS of the ESX server where the VM is executing. First, you need the ID of the VM (all on one line if it wraps): /usr/bin/vmware-cmd /vmfs/volumes/datastore-name/vm-folder/vmx-file.vmx getid Then you can do …

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