System Administration

Labels Should Only List Properties of That Particular Object

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Labels should only list properties of the object to which they’re affixed. This may mean some education about the hierarchy of things, but, with very few exceptions, putting a label on one object with data that belongs to another object is a recipe for problems later. “What problems?” you ask. Well, at the least you’re increasing the amount of work you need to do when you change something. Got IP addresses on your cable labels? Add an IP to a server and you need to change the cable’s label, too, otherwise you have incomplete documentation. Same thing with DNS names, too. Or application information. Incomplete and incorrect data on labels leads to assumptions, and assumptions lead to outages, problems, and …

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Fibre Channel over Token Ring Presentation @ WI VMUG

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I made a presentation to the Wisconsin VMware Users’ Group on Tuesday, January 18, 2011 on the Fibre Channel over Token Ring Alliance and its role in the future of the technology. It was short and it turned out pretty well, and I have to thank all the attendees, as well as Rod Gabriel, for laughing at the right spots and having a good sense of humor. We need more humor between vendor presentations, for sure. The notes for the slides are below each. I am not aware that a video was made, but if you know of one leave me a comment. Thanks! Put simply, FCoTR is the best features from two proven technologies, married into the storage protocol …

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How to Configure Remote syslogd on Red Hat/CentOS 5

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It’s fairly easy to configure syslogd on one host to accept syslog messages from other hosts. This is useful in normal system administration, to keep logs off the original system in case of a security breach that might compromise them, as well as for systems like VMware ESXi which don’t store logs locally due to their architecture. This assumes a basic level of familiarity with Linux, particularly the Red Hat types of distributions (Red Hat Enterprise Linux, Fedora, CentOS, Scientific Linux, Oracle Enterprise Linux, etc.). The concepts are likely the same for other distributions. I used Red Hat Enterprise Linux 5 and I’ll assume you are able to handle the provisioning of a similar host for your purposes. I also …

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Dear Microsoft: One Central Update Framework

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Dear Microsoft, I really like Windows 7. A lot. It’s most of what I was looking for in Windows Vista, and a worthy successor to Windows XP. You left one big thing out, though. I have, beyond Windows itself, at least 28 applications that automatically check for updates: Adobe Acrobat, Adobe AIR, Adobe Flash, Adobe Photoshop, Adobe Illustrator, Adobe Lightroom, Apple iTunes, Apple Airport, Apple MobileMe, Apple Safari, Autopano Giga, Piriform CCleaner, Piriform Defraggler, Dell Client System Update, Evernote, Google Chrome, Metageek inSSIDer, Oracle Java, Last.fm, LogMeIn Hamachi, Microsoft Security Essentials, Mozilla Firefox, Mozilla Thunderbird, Skype, Tweetdeck, uTorrent, VanDyke SecureCRT, and VLC Media Player. My life is one big parade of pop-ups, warnings, toolbar installation offers, and auto-updaters. Would I …

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How To Create and Measure NTFS & ext3 Disk Fragmentation

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From time to time I need to test things related to disk fragmentation, like the performance of fragmented versus unfragmented disks, or how well a disk defragmenter works. Rather than trying to find machines with fragmented disks I decided to generate fragmentation on my own. It’s actually quite easy to generate a fragmented disk on NTFS or ext3 filesystems. Fragmentation happens when you don’t have much free space on disk and a filesystem is forced to use non-contiguous blocks to fulfill requests. So we just encourage that behavior by filling the drive with a bunch of small files, then freeing some space by truncating those files to a smaller size. Then we fill the free space again by growing those …

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Keys To Virtualization Success

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I’ve been thinking a lot lately about what has made my virtualization journey successful so far. There are eight good reasons for my success, four of which tend to be more technical than the rest: a test environment, not breaking vMotion, N+1 capacity, and maintenance windows & good patching practices. 1. A respectable test environment. I have four physical hosts (two older hosts, two newer hosts) configured in two clusters where I can try new things, test patches and upgrades and functionality, run a couple test VMs for each OS we support, develop procedures, train staff, do demos, and generally muck around without affecting production. I run the test vCenter instance for these hosts as a VM in my production …

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Amazon & WikiLeaks, DMCA & Perils of Public Clouds

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On December 1, Carl Brooks of TechTarget published a piece entitled “Amazon boots WikiLeaks under pressure from U.S. Senator.” Yesterday he implored them to release a statement about what actually happened. I agree with him. I’d like to know what happened, replacing rampant speculation with as many facts as possible. Perhaps the delay is to permit Amazon’s lawyers time to sort this out, especially if it’s true that Lieberman interfered. It also may be true that their shutting WikiLeaks down has legal implications for them under DMCA Safe Harbor provisions. As stated by the chillingeffects.org DMCA Safe Harbor page: In order to qualify for safe harbor protection, a service provider who hosts content must: have no knowledge of, or financial …

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Spread Linux’s Default Scheduled Jobs Out

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By default, Linux distributions ship with a number of system maintenance tasks. On Red Hat Enterprise Linux (and CentOS, and OEL, etc.) they are scheduled via shell scripts in the /etc/cron.* directories, and executed by anacron. The problem is, there’s usually a default time they are executed, like 0400. And when you have 300 RHEL virtual machines all rotating their logs at 0400 you start seeing storage and CPU performance problems, as copies are made and logs are compressed. This can be true of hosts attached to SAN/centralized storage, too. If we ignore backup windows[0], my RHEL 5 hosts had three main offenders: /etc/cron.daily/logrotate: kicks off /usr/sbin/logrotate to trim and compress log files in /var/log. /etc/cron.daily/mlocate.cron: part of the mlocate …

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It isn’t so much that Oracle now supports VMware…

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I’ve been seeing a lot of commentary on the Oracle support policy change that happened last week, and I think some people are missing a big distinction here: It isn’t so much that Oracle now supports VMware, but that Oracle no longer doesn’t support VMware, if that makes sense. They aren’t supporting VMware, but they aren’t not supporting it, either.[0] Article 249212.1 in Oracle’s Metalink states: Oracle has not certified any of its products on VMware virtualized environments. Oracle Support will assist customers running Oracle products on VMware in the following manner: Oracle will only provide support for issues that either are known to occur on the native OS, or can be demonstrated not to be as a result of …

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If You Ever Needed Convincing About VAAI…

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If you needed any convincing about the benefits of VAAI, here’s a graph of what happened when I took our new VAAI-capable HDS AMS 2500, copied a 25 GB template VM to it, then cloned three more VMs from that template. I did the cloning one at a time, rather than in parallel, mainly because I was in shock that it took about 30 seconds for each one to complete and in my giddiness I didn’t think to do any other testing. I have only the Hitachi write rate highlighted, but that tells the story: So far, the only drawback I can see to the new VAAI offloads are just that you’ll need to rely more heavily on your array’s …

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