Showing posts from February, 2011

Fixing failing BIOS updates on R710 in Linux

Dell's OMSA is great for maintaining and updating a Dell server's firmware, if it works... Dell does a great job so far, but sometimes little quirks mess up small parts and suddenly OMSA will update all or nothing or only a few and then call it quits.

pjwelsh has written a handy little summary of the various ways with which you can try to still get working, albeit manually: Failed BIOS update on Dell R710 with CentOS 5.5 solved! (Worked around, really)

Dell's Ubuntu certification details

Dell recently published a little more details about what Ubuntu Certified and Ubuntu Ready means. Even though Dell does not officially support Ubuntu, their hardware is labelled as Certified by Canonical and they can also provide with paid support for Enterprises that require it.

Oracle Public Yum Server

Besides having the option to download installation media from Oracle (for which you must register), you can use the Oracle Public Yum Server to get packages. For instance, to help solve ad-hoc dependencies. This alleviates you from the need to keep a local mirror available for all Linux releases.

Tuning Journaling File Systems

Also found this great but slightly dated resource on Tuning Journaling File Systems.

We had a crash of a VM recently with 3 million small files in a single directory. Tuning some mounts with noatime and dir_index helped a lot. Still tinkering with journaling options, though.

Oracle Linux 6 Release Notes

A few days ago, Oracle followed suit by Red Hat and released OEL6. Here are the Oracle Linux 6 Release Notes.

At first glance, most notable changes are default ext4 file system. Better performance monitoring and tracking using perf and new user space "top" tools, and it no longer uses up2date but instead relies totally on yum. Yummie! Last but not least: the Unbreakable Kernel kernel-uek-2.6.32-100.28.5.el6 is installed and activated by default! This shouldn't matter much, unless you run the latest state-of-the-art hardware and use SSDs a lot. But 3rd party software vendors may like you stepping away from the Red Hat default kernel-2.6.32-71.el6 kernel. So check first!

OL6 is the first Linux distribution from Oracle where they no longer patch the Red Hat kernel. Instead, they provide the Red Hat kernel as-is as an option to be configured for use in /etc/grub/menu.lst. The default kernel in OL6 is the Unbreakable Enterprise Kernel that Oracle maintains itself. As far as I…

Byte-aligning Linux partitions on modern disks

Linux uses 512-byte sectors. Hard disks used to too. The emergence of huge TB-sized disks has caused manufacturers to changed to 4096-byte sectors. This change can cause performance degradation on Linux as it's partitions may not be aligned with these bigger sectors. The additional overhead for the disk causes a performance drop.

This raises the need for aligning your Linux partitions to the new sector size. However, many tools such as fdisk and parted are not yet doing this for you easily. IBM DevWorks has a great in-depth article on the topic: Linux on 4KB-sector disks: Practical advice

Scripting Partition Creation In Linux

I knew I could use fdisk in Linux to create partitions for me from a script. This can come in handy during kickstart for (re)deployment of a server and you don't want to let anaconda handle partitions for you. Or you simply want to be absolutely sure things go as you want, instead of relying on software with unknown bugs or quirks.

I knew you can use something like:
fdisk /dev/sda << EOF n p 1 t 8e q EOF to partition /dev/sda for you with one large partitions and give it type 8e (LVM). (The 'q' is so that those who simply copy this, don't immediately wipe some disk.) But I was looking for somewhat cleaner, more intuitive style. James Stephens pointed out the use of sfdisk from scripts. While I don't know if sfdisk is less reliable than fdisk or parted, or how to handle byte-aligning disks [1] [2] [3] from these scripts, it's a good place to start and I wanted to document it here.