Virtualization

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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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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ThinApp Starter Edition

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Have you wanted to take a look at ThinApp? VMware has a new product: ThinApp Starter Edition. Until April 30, 2011 it’ll be a free download for new Workstation customers. It’s missing the AppSync and Permitted Groups functionality, but if you like what you see and want to upgrade to the Enterprise versions you can roll your work forward. Successfully predicting a wave of people wondering if they can get in with their existing Workstation 7 license keys, VMware has set up a site where you can get a license key for Starter Edition: http://www.vmware.com/products/workstation/thinapp-starter-edition-form.html Remember to remove the dashes/hyphens from your key. This will only work for a week or so in honor of the VMware Communities Podcast, so …

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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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Apple, Xserves, and OS X Server

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Apple will not be developing a future version of Xserve. Xserve will be available for order through January 31, 2011. Apple will honor and support all Xserve system warranties and extended support programs. Apple intends to offer the current shipping 160GB, 1TB, and 2TB Apple Drive Modules for Xserve through the end of 2011 or while supplies last. Apple will continue to support Xserve customers with service parts for warranty and out-of-warranty service. As of January 31, 2011 Apple will no longer have enterprise-class hardware for sale. This has sparked a massive discussion, because there are a number of pretty vocal people using Xserves to run Mac OS X Server, supporting Mac OS X clients, or as clusters running Xgrid. …

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Remember Permissions on Virtual Switches

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Is one of your VMware vCenter users trying to alter the network settings on a virtual machine? Is it telling them that the network adapter has “Invalid backing” and the network connection information says “this host does not have any virtual machine networks, or you don’t have the permission to access them?” But you checked the permissions on the VM, and they do have permissions… And their role does have the privileges to assign networks to virtual machines… … Before you bang your head against it too much, check Inventory->Networking. You may have forgotten to assign them permissions to the switch itself! (this post brought to you by the last 30 minutes of my life) 🙂

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