We has tubez!

So in the land of VMware, and most other hypervisors, we have a great technology called “snapshots”.
You’ve probably landed on this page because when you try to delete a snapshot, it’s taking forever.
If that’s the case, I have to ask… How long have you had this snapshot? And how much data has been written since it was taken?

To understand how snapshots operate, it’s important to understand the composition of your average virtual machine. To be fair, various virtualization architectures exist, but VMware’s is fairly straightforward. Every virtual machine consists of two parts, a *.vmx, and a *.vmdk. You’ll fairly frequently see other components, but in the end, if you do not have a *.vmx, and a *.vmdk, you don’t have a virtual machine. As we dive a little deeper, the *.vmdk consists of two parts:

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Just got an email this morning regarding the immediate availability of PS Series firmware v 5.0.5.

It’s recommended for installation ASAP, so plan accordingly, especially if you’re using replicated volumes!

Issues Corrected in This Version
Changelog & Issues corrected in this version are described below:

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So I’m working on migrating few routed IP’s which are attached to my company’s cable modem over to a CIDR block of IP’s provided by our ISP (COX Communications).

Here’s the situation, apparently there’s a limit to the number of WAN IP’s that can be attached directly to your cable modem. In this case COX says that it’s 8 (this is an arbitrary number, but whatever). If you need more, you need to procure what’s called a CIDR block. Basically this is a block of addresses which is outside the subnet range of you modem’s WAN IP. Your ISP will then next hop the CIDR to your WAN IP, and it’s your job to take it from there. So instead of being able to tack a switch between your modem and your router to be able to assign WAN addresses to your server’s network cards, we need to use a router which can translate the forwarded CIDR block requests.

GREAT! I have a very nice router already! Enter the Juniper SSG-140, which is being replaced by the SRX series of devices running JUNOS, I digress however, as that’s a post better left for another time.

We initially had a number of issues trying to duplicate features that are available when you have additional IP’s that are inside your WAN subnet. Features like MIP, VIP, and the ability to attach a WAN address directly to a server’s NIC. (I know this isn’t best practice, however we have a deployment of Office Communications Server 2007 non-R2, which requires that a WAN IP be present on the NIC serving the Audio / Video Conferencing role.)

I’ll be making another post on how to duplicate all of the above functionality a little later I promise, but this post is about a NAT-DST port forwarding gotcha I encountered on me being retarded.

When you normally setup your home router, you specify the source and destination port that you want requests to be forwarded to. This is most often referred to as port forwarding, however here’s where the gotcha happens. Say you translate port 80 on your WAN IP to port 8080 on your internal network, you would actually be doing port shifting. Forwarding as it comes to mind of most people means your taking the wan port and passing it to an internal server with the same port.

When dealing with enterprise switches, you’ll often run into Source port and Destination port when referring to policies and services to go along with those policies.

I made the mistake of thinking that the source port in the screenshot above was the source port of the WAN IP address.
It’s actually the source port of the originating computer, the destination port is the destination of their request.

So you can see that I want all ports from the source computer to be accepted when requesting ports 18082, 18086, and 18087 on my WAN IP.

Remember to read and understand your networking equipment or you’ll end up like me and spend a couple hours troubleshooting something that was as easy as this.

As I keep digging into documents and KB articles I keep finding more and more things to like about vSphere 4.1. Today’s find has to do with the PVSCSI driver.

With the release of vSphere 4.0, VMware added a new paravirtualized SCSI driver into the VMware Tools that provides better virtual disk performance than the standard LSI driver. The PVSCSI driver promised to deliver better performance and lower overall CPU utilization for workloads that had high I/O demands. Unfortunately the PVSCSI driver wasn’t supported on virtual machine boot volumes, so folks held off on making this the default SCSI driver for all virtual machines.

After vSphere 4 Update 1 was released, VMware lifted the restriction and now supported the PVSCSI driver on boot volumes. Folks began considering adopting the PVSCSI driver in all virtual machines similar to how the VMXNET driver is a standard for nearly all virtual NICs. Soon afterwards VMware came out with a knowledgebase article stating that virtual machines that did not have heavy I/O demands could actually experience worse performance using the PVSCSI driver. YIKES!!! They recommended only using the driver for workloads that had I/O demands in excess of 2,000 IOPS.

With the release of vSphere 4.1 that is no longer a problem and you can use the PVSCSI driver in all circumstances.
Want details? Read on!

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So many of you may find this site looking to see where I’ve gone, and why I’m not on Hak5 any longer.

While this is a brief post I promise I will write up a longer more appropriate post for you shortly.

Short and sweet of it is, I’ve decided to move on and focus my energy on my career, business opportunities and my undying love of internet radio.

I’ll be bringing back my internet talk show soon, and if you’re ever at an SAP conference focusing on infrastructure or virtualization, you might see me presenting

Like I said, a more thought out post is coming shortly, and I’ll be posting on my blog pretty regularly with updates on things going on in my life.

Thanks to all the great I’ve met over the last 2.5 years, you have truly made them unforgettable!