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Showing posts from September, 2007

Why does Linux clock keep running too fast or too slow in VMware?

I noticed this myself a few months ago but thought ntp needed to get in sync and stabilize and forgot about it until a new colleague alerted me to Linux kernel timing...
Since the ESX host runs at a certain clock tick rate (usually 1000 per second) and Linux guests (VMs) also run at that rate (if kernel >= 2.6.x), you get a mismatch between real and virtual clock ticks. So interrupts get missed, never happen or keep happening. Either way, time gets skewed and this can lead to serious issues.
VMware is aware of this issue and their Knowledge Base offers a few fixes and work-arounds for ESX 2, 2.5 and 3 (i.e. VI3). The basic thought is to increase the tick rate for the ESX host, or to limit the tick rate for the VM.

The new tick-less kernel may also provide a great solution, but support for this by Oracle or VMware is yet unknown.

LessWatts.org - Saving Power on Intel systems with Linux

Did you know that you can often save real power on your machine, even without updating any of the software? The site LessWatts.org contain a set of tips and tricks, contributed by community members and Intel engineers, to help you find the best power tuning for your laptop, desktop, or server. Highly recommended!

Technology Tracks | Oracle OpenWorld 2007

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If you are in or near San Francisco in November, be sure to check out the Technology Tracks of Oracle OpenWorld 2007. There is a whole track for Linux and open source. Not just the Oracle Enterprise Linux itself, but also development, testing and optimizing of and on Linux.

OneCMDB: open source ITIL CMDB software

While waiting for HP Openview to complete and manage everything, we found the need to get a program to help maintain and organize the quickly growing pile of servers, firmware versions, hostnames and WWPN numbers. Luckily, SourceForge is a never ending treasure chest of open source software and OneCMDB seems to fit... will try!

ZFS, XFS and EXT4 filesystems compared

Found a nice article on a benchmark study of the new, modern file systems that are coming up. ZFS, XFS, and EXT4 file systems compared shows how ZFS, XFS and ext4 measure up against each other.
Of course, there is no reference measurement of zero-line to compare against. But perhaps other benchmark studies can provide this...

Brocade joins Oracle Linux program

Brocade, network storage solutions provider today announced that it has joined the Oracle Unbreakable Linux program-providing full interoperability between Brocade Storage Area Network (SAN) switches and the Oracle Enterprise Linux.

The companies running Oracle Enterprise Linux can now integrate and deploy Brocade switches with a wide range of products from other leading SAN solution providers. Brocade is also a member of Oracle Partner Network, Brocade said in a statement. Read more...