Virtualization

What Kind Of Servers Should I Buy for VMware?

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Another frequently asked question: What kind of servers should I buy to start my VMware cluster out? My off-the-cuff answer: “the biggest machines you can afford at least three of, from whatever vendor you like the most,” followed by “it depends.” Part of the great thing about virtualization, especially with VMware, is that you can use VMotion to move everything off of a running machine. This means that you need a place to put that workload, though (think of my “buckets of water” analogy). If you buy two machines you have to keep one empty, and 50% of your cluster capacity sits idle. If you buy three machines you can use two of them, and 33% of your cluster capacity …

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Should I Convert My Old Servers to ESX?

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Frequently asked question: My company is virtualizing our data center. Should we buy new servers or turn the ones we have into ESX servers? My usual answer is a question: “How old are the servers you have?” Average answer: “Somewhere around three years old.” My reply: “Get new servers.” Why new servers? Because, performance-wise, they smoke your old servers, and have all the new technologies like Extended Page Tables, VT-x, VT-d, etc. RAM is often a limiting factor for how many VMs you can get on a physical host. Newer servers can have lots of RAM on them, more inexpensively than old servers can have lots of RAM on them. New servers often come with four NICs built in — …

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How Much Capacity Should I Have For VMware?

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Frequently asked question: How much capacity should I have in my VMware environment? My stock answer to this: N+1 in each cluster. If you have N physical hosts worth of work in a cluster, have N+1 physical hosts. That way you have spare capacity for maintenance operations, and you can take a whole server completely out of the cluster by VMotioning its workload to the spare machine. Think about your servers as buckets, and your workload as water. If you have 30 gallons of water in 6 buckets, where will you put 5 gallons of water when you need to drain one of the buckets? You need an empty bucket that’s as big as the largest bucket you have. In …

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Intel Xeon 5500 Release

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I’ve spent the morning looking at the new server models from Dell, based on the Intel Xeon 5500 series of CPUs (Nehalem-EP). These things look sweet, but there are some interesting caveats. A few of my observations so far: 1. Intel has killed the front-side bus and in its place implemented QuickPath Interconnect (QPI), a competitor to AMD’s HyperTransport. It’s speed is measured in GigaTransfers per second (GT/s), and is 4.86 GT/s, 5.86 GT/s, or 6.40 GT/s per direction, which according to the Wikipedia article I linked to is 12 to 16 GB/s per direction per link. Cool, but most people are going to pick a CPU based on price point rather than link speed, given that everything in the …

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Not Running VMware Capacity Planner as root on Linux

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I’ve recently been working with VMware Capacity Planner project in my organization. It’s a useful tool in proving what I already know: that the physical hosts in my data center don’t do anything. 🙂 The Capacity Planner Data Manager is a software component that you install at your site on a Windows host (in my case a virtual machine). It gathers data from your hosts, sanitizes it, and relays it or stores it for relaying to VMware’s data warehouse (where it’s analyzed). One of Data Manager’s features is that it’s agentless, and will just SSH into my Linux hosts and gather what it needs. Problem with that, though, is that it wants to log in as root. All the documentation …

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How File Deletions Work

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Q: I deleted a bunch of files from one of my virtual machines yesterday. Deduplication happened overnight, but the total disk space in use didn’t go down. That doesn’t make any sense. Q: I completely evacuated one of the LUNs on my NetApp array, but the NetApp still says that the LUN is almost completely full, even after deduplication. How can that be? A: To understand what is happening you need to know a little bit about how a file system works. A simple way to explain it is that a file system stores the data in a file as data blocks, and it stores the name of the file (and other data, like access times, etc.) in a directory …

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Green Data Centers

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When asked about making our data center a green data center, my friend and coworker Terry Bradshaw always responds with: “Sea foam or forest, you can have it in any color green you want.” There really isn’t a way to make a data center green beyond painting it. Your corporation, your organization can go green. Your data center can’t. You can certainly make it more green (or, rather, less not-green) by making it more efficient. But no matter how efficient it is it’ll still be a power-hungry room stacked full of metal boxes made via environmentally-unfriendly techniques, each filled with toxic chemicals and requiring hazardous waste disposal techniques when their lives are over every few years. Virtualization can certainly improve …

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Windows 7 Beta and VI Client

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I thought I’d really be pushing my luck, but it appears that the VMware Virtual Infrastructure Client (Build 119598) runs fine on the 64-bit Windows 7 beta (Build 7000). I only have the basic client and the Update Manager plugins installed, but both appear to work. I’ve done a solid 15 minutes of testing so far, so YMMV. 🙂 It’s probably also worth mentioning that my test Windows 7 host is a VM in my VI 3.5 U3 cluster. Seems to work — the VM is set to Windows Server 2008, and the VMware Tools seem to work fine. I didn’t install the Shared Folders functionality. It sure is nice to take snapshots along the way as I install more …

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How To Grow Linux Virtual Disks in VMware

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There is plenty of documentation for how to grow a VMware virtual disk file (VMDK), but there doesn’t seem to be a lot of documentation for Linux users who A) are using LVM and B) have aligned their partitions for performance reasons. I was asked how to do this and I thought I’d post it here for everybody. I basically have two suggestions. One is straightforward but you end up with two partitions in your volume group. The other is a little scarier but you’ll have only one partition in the end. This last method is what I was asked about, and what I’ll go into detail explaining. Obligatory, seemingly obvious statement: have a backup of your system. This is …

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I'm Gonna Virtualize You Fools

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This is probably real old news, but I just saw the Mr. T “I am the T in I.T.” video from Hitachi today. Corny, no doubt, but lines like “intelligence in the network is for suckas” make me laugh. My goal for next week is to use “I’m gonna virtualize you fools” in conversation at least once.

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