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	<title>Blog O' Matty</title>
	<link>http://prefetch.net/blog</link>
	<description>Blog O' Matty</description>
	<lastBuildDate>Sat, 13 Mar 2010 15:28:36 +0000</lastBuildDate>
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	<language>en</language>
	
	<item>
		<title>Problems growing RAID6 MD devices on RHEL5 systems</title>
		<description><![CDATA[I attempted to grow an existing RAID6 MD device this week, and ran into the following error when I performed the grow operation:
$ mdadm &#8211;grow &#8211;raid-devices=5 &#8211;backup-file=/tmp/mdadmgrow.tmp /dev/md0
mdadm: Need to backup 384K of critical section..
mdadm: Cannot set device size/shape for /dev/md0: Invalid argument
It appears the ability to grow a RAID6 device was added in the [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/13/problems-growing-a-raid6-md-device-on-rhel5-systems/</link>
			</item>
	<item>
		<title>Debugging syslog-ng problems</title>
		<description><![CDATA[While debugging the syslog-ng issue I mentioned previously, I needed to be able to observe the syslog-ng pattern matches as they occurred. The syslog-ng daemon has a couple of useful options to assist with this. The first is the &#8220;-e&#8221; option, which causes the daemon to log to stdout. The second is the &#8220;-F&#8221; option, [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/09/debugging-syslog-ng-problems/</link>
			</item>
	<item>
		<title>Breaking down system time usage in the Solaris kernel</title>
		<description><![CDATA[I am frequently asked (or paged) to review system performance issues on our Solaris 10 hosts. I use the typical set of Solaris performance tools to observe what my systems are doing, and start drilling down once I know if the problem is with userland applications or in the kernel itself. When I observe issues [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/08/breaking-down-system-time-usage-in-the-solaris-kernel/</link>
			</item>
	<item>
		<title>Great write-up on AMD&#8217;s RVI (Rapid Virtualization Indexing) hardware assisted virtualization feature</title>
		<description><![CDATA[I came across an awesome Q&#038;Q where Tim Mueting from AMD described the hardware virtualization features in AMD Opteron CPUs. The following excerpt from the interview was especially interesting:
&#8220;Prior to the introduction of RVI, software solutions used something called shadow paging to translate a virtual machine “guest” physical address to the system’s physical address. Because [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/07/great-write-up-on-amds-rvi-rapid-virtualization-indexing-hardware-assisted-virtualization-feature/</link>
			</item>
	<item>
		<title>Viewing the scripts that run when you install a Linux RPM</title>
		<description><![CDATA[RPM packages contain the ability to run scripts after a package is added or removed. These scripts can perform actions like adding or removing users, cleaning up temporary files, or checking to make sure a software component that is contained within a package isn&#8217;t running. To view the contents of the scripts that will be [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/07/viewing-the-scripts-that-run-when-you-install-a-linux-rpm/</link>
			</item>
	<item>
		<title>Creating a bootable OpenSolaris USB thumb drive</title>
		<description><![CDATA[This past week, I had the need to install opensolaris on a host using a USB thumb drive. To create a bootable USB drive, I first needed to snag the distribution constructor tools via mercurial (I ran these commands from an OpenSolaris host):
$ pkg install SUNWmercurial
$ hg clone ssh://anon@hg.opensolaris.org/hg/caiman/slim_source
The caiman slim source Mercurial repository contains [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/07/creating-a-bootable-opensolaris-usb-thumb-drive/</link>
			</item>
	<item>
		<title>My quest for the perfect fruit smoothie</title>
		<description><![CDATA[I have been a smoothie addict for several years, and recently got interested in saving some cash and making my own (at $5 a smoothie, the commercial smoothie shops were making $60+ from me each month!). To begin my quest for the perfect smoothie, I had to define a few requirements:
- Smoothies needed to be [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/02/my-quest-for-the-perfect-fruit-smoothie/</link>
			</item>
	<item>
		<title>Getting syslog-ng to filter messages by source IP address</title>
		<description><![CDATA[I received a call this week from one of our network guys because messages from several network devices weren&#8217;t being logged by our centralized log server. When I started debugging the issue, I noticed that traffic from the hosts (host1 in this example) was making it to our syslog-ng server:
$ tcpdump -i eth0 host host1

tcpdump: [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/03/02/getting-syslog-ng-to-filter-messages-by-source-ip-address/</link>
			</item>
	<item>
		<title>VTL project for Linux</title>
		<description><![CDATA[I came across the Linux tape library project website the other night, and this looks like a sweet project. If we could combine this solution with ZFS, the combination would be truly incredible! I need to install the LVTL software in my lab and give it a spin!
]]></description>
		<link>http://prefetch.net/blog/index.php/2010/02/21/vtl-project-for-linux/</link>
			</item>
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		<title>Why isn&#8217;t Oracle using huge pages on my Redhat Linux server?</title>
		<description><![CDATA[I am currently working on upgrading a number of Oracle RAC nodes from RHEL4 to RHEL5. After I upgraded the first node in the cluster, my DBA contacted me because the RHEL5 node was extremely sluggish. When I looked at top, I saw that a number of kswapd processes were consuming CPU:
$ top

top - 18:04:20 [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/02/11/why-isnt-oracle-using-huge-pages-on-my-redhat-linux-server/</link>
			</item>
	<item>
		<title>Titan Quest is an awesome action role playing game!</title>
		<description><![CDATA[For as long as I can remember, I have always been a fan of the &#8220;hack and slash&#8221;-type action role playing games. I started out years ago playing Diablo, and eventually purchased Diablo 2 and all of the add-ons. Since Diablo 3 isn&#8217;t slated to be released for a few more months, I started looking [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/01/21/titan-quest-is-an-awesome-action-role-playing-game/</link>
			</item>
	<item>
		<title>Why oh why is grub eating CPU resources in a VirtualBox VM?</title>
		<description><![CDATA[While reviewing the performance on my desktop today, I noticed that one of my VirtualBox virtual machines was consuming 100% of one CPU:

Swap:  2097144k total,    59504k used,  2037640k free,  4004568k cached

  PID USER      PR  NI  VIRT  RES  SHR S [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/01/12/why-oh-why-is-grub-eating-cpu-resources-in-a-virtualbox-vm/</link>
			</item>
	<item>
		<title>Configuring and monitoring the T5220 hardware RAID controller</title>
		<description><![CDATA[The Sun T5220 comes with a built-in RAID controller, which supports all of the standard RAID levels (0 &#8211; 6). Configuring one or more devices to participate in a RAID Configuration is dead simple, since you can use the Solaris raidctl utility. The last T5220 I configured had a root file system that was going [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/01/12/configuring-and-monitoring-the-t5220-hardware-raid-controller/</link>
			</item>
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		<title>Awesome vSphere server videos</title>
		<description><![CDATA[While I was studying for the VCP4 certification, I watched a number of awesome educational vSphere videos from Mike Laverick. Mike did a killer job with the videos, and they clearly explain a number of vSphere technologies in detail! Thanks a ton Mike for making these available!!!
]]></description>
		<link>http://prefetch.net/blog/index.php/2010/01/01/awesome-vsphere-server-videos/</link>
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		<title>How to become a VMware certified professional (VCP4)</title>
		<description><![CDATA[I passed the Vmware certified professional 4 (VCP4) exam this past Monday. The exam was a bit more difficult than I expected, though I passed it with flying colors. If you are thinking about taking the exam, or are interested in learning more about vSphere, you will definitely want to start out by reading Scott [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2010/01/01/how-to-become-a-vmware-certified-professional-vcp4/</link>
			</item>
	<item>
		<title>Using the Linux parted utility to re-create a lost partition table</title>
		<description><![CDATA[I ran into an issue last week where two nodes using shared storage lost the partition table on one of the storage devices they were accessing. This was extremely evident in the output from fdisk:
$ fdisk -l /dev/sdb

Disk /dev/sdb: 107.3 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/20/using-the-linux-parted-utility-to-re-create-a-lost-partition-table/</link>
			</item>
	<item>
		<title>Creating Linux bridging / tap devices with tunctl and openvpn</title>
		<description><![CDATA[The more and more I play around with KVM virtualization, the more I realize just how useful Linux bridging is. In the Linux bridging world, a bridge device simulates a multiport Ethernet switch. To connect to the switch, you create a tap device that simulates a port on that switch. Once you have bridging configured [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/20/creating-linux-bridging-tap-devices-with-tunctl-and-openvpn/</link>
			</item>
	<item>
		<title>Backing up your COMSTAR storage configuration</title>
		<description><![CDATA[I have been playing around with the COMSTAR iSCSI and FC port providers for the past few months, and other than a number of problems with the emlxs driver, they appear to work pretty well. As I&#8217;ve been experimenting, I wanted to back up my configuration in case something happened to my server. COMSTAR uses [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/20/backing-up-your-comstar-storage-configuration/</link>
			</item>
	<item>
		<title>Expanding VMWare guest storage and extending LVM volumes and ext3 file systems to use the new storage</title>
		<description><![CDATA[One of my production vSphere virtual machines came close to running out of space this past week. Expanding guest storage with vSphere is a breeze, and I wanted to jot down my notes in this blog post. To expand the size of a virtual disk, you will need to open the virtual infrastructure client, right [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/13/expanding-vmware-guest-storage-and-extending-lvm-volumes-and-ext3-file-systems-to-use-the-new-storage/</link>
			</item>
	<item>
		<title>Keeping up to date with CentOS happenings</title>
		<description><![CDATA[I just found out the folks in the CentOS community have a planet feed! If you are interested in keeping up to date with all things CentOS, you should add their feed to your RSS reader.
]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/13/keeping-up-to-date-with-centos-happenings/</link>
			</item>
	<item>
		<title>Configuring an OpenSolaris host to use a static IP address</title>
		<description><![CDATA[I installed OpenSolaris 2009.06 yesterday, and noticed that the installer doesn&#8217;t give you the option to configure a static IP address. Network address are retrieved via DHCP, which isn&#8217;t an option for this host. To configure the host to use a static IP address, I changed the /etc/nwam/llp file. Here is the file before:
$ cat [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/13/configuring-an-opensolaris-host-to-use-a-static-ip-address/</link>
			</item>
	<item>
		<title>Generating Netbackup throughput data reports</title>
		<description><![CDATA[If you support Netbackup at your site, I&#8217;m sure you&#8217;ve had to look into issues with slow clients and failed backups. The nbstatus script I mentioned in a previous post is useful for identifying connection problems, but it doesn&#8217;t help you understand how well your clients are performing. To help me understand how much data [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/12/generating-netbackup-throughput-data-reports/</link>
			</item>
	<item>
		<title>Fixing Solaris hosts that boot to a grub&gt; prompt</title>
		<description><![CDATA[I applied the latest recommended patch bundle this week to two X4140 servers running Solaris 10. When I rebooted, I was greeted with a grub> prompt instead of the grub menu:
grub>
This wasn&#8217;t so good, and for some reason the stage1 / stage2 loaders weren&#8217;t installed correctly (or the zpool upgrade caused some issues). To fix [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/12/fixing-solaris-hosts-that-boot-to-a-grub-prompt/</link>
			</item>
	<item>
		<title>Watching process creation on Linux hosts</title>
		<description><![CDATA[I have been debugging a problem with Redhat cluster, and was curious if a specific process was getting executed. On my Solaris 10 hosts I can run execsnoop to observe system-wide process creation, but there isn&#8217;t anything comparable on my Linux hosts. The best I&#8217;ve found is systemtap, which provides the kprocess.exec probe to monitor [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/10/watching-process-creation-on-linux-hosts/</link>
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		<title>Cleaning up space used by the OpenSolaris pkg utility</title>
		<description><![CDATA[I&#8217;ve been experimenting with the new OpenSolaris package manager (pkg), and ran into an odd issue last weekend. The flash drive I was running image-update on filled up, and after poking around I noticed that /var/pkg had some large directories:
$ cd /var/pkg
$ du -sh *

4.6M    catalog
1.5K    cfg_cache
892M   [...]]]></description>
		<link>http://prefetch.net/blog/index.php/2009/12/06/cleaning-up-space-used-by-the-opensolaris-pkg-utility/</link>
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