Archive for October, 2009

SATA cable fault causes disk system to timeout

While setting up Nexenta 3.0 on a Intel SS4200, I hit this error: “transport failed reason tran_err“. The reason – a SATA cable was caught and being compressed between a drive cage and the case.

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kvm vs qemu-kvm vs kvm-kmod

Ubuntu recently change their package names for kvm.  This comment posted on qemu-0.11.0 Released provides an explanation:

qemu-kvm includes features and fixes from upstream qemu and so takes its naming scheme from upstream qemu. You can think of it as qemu optimized for kvm. Note too that qemu-kvm does not include the kernel module but only the userspace and considered to be stable.

kvm-xx on the other hand is the development branch of kvm and not considered to be stable. It’s naming scheme is arbitrary and it also takes features from upstream qemu.

kvm-kmod is different to kvm-xx. You can think of kvm-kmod as a subset of the kvm-xx. KVM-xx = userspace + kernel where kvm-kmod is the kernel part of it and qemu-kvm is the userspace part (the guest process itself). You can apply the kvm-kmod to any distro version or linux version.. it’s just the kernel driver. However, without the userspace part, you can’t do much with it.

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Alfresco and IMAP

This is something I’ve been wanting in a DMS for a while. Alfresco now have native IMAP support. They also offer apt-get installable goodness for januty. It is possible there is some performance issues with the IMAP functionality, but I’m sure these will be fixed.  It might be time for me to do another review the DMS landscape.

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Upgrading wordpress – please do

A popular NZ blog I follow got infected by something like the worm mention in this post. They were running a very old version of wordpress, 2.5.X or some such. When I spoke to one of them, they said they knew they were running an old version, but their answer was move to drupal. It just had not happened yet.  While their move might be for other reasons than security, leaving a public piece of software unmaintained while waiting for a replacement is a bad idea.

Upgrading wordpress is now pretty seamless. Please follow the advice in the wordpress post.

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Jaunty and md

Not to disrespect Ubuntu, but Jaunty must be the worse release they have made in a long time. Whether it be an unusable desktop because of a poor kernel – upgrading to 2.6.30 is a good idea – or just poor packaging – md overwriting the mdadm.conf file? WTF?  See here and here for the workaround lists, and here to fix the md issue.

Karmic is getting good reviews. Lets hope its an easy upgrade and sets the scene for an amazing 10.4 release.

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kvm disk performance with different backends

Here  some results from testing I did in August 2009 on  KVM with the three different disk image drivers. First a single disk system running Ubuntu x64 9.04:

Read the rest of this entry »

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50% Performance Boost for Nehalem’s over Harpertown

From the vmware blog:


A 1vCPU Xeon X5500 series based Exchange Server VM can support 50% more users per core than a 2vCPU VM based on previous generation processors while maintaining the same level of performance in terms of Sendmail latency.  This is accomplished while the VM’s CPU utilization remains below 50%, allowing plenty of capacity for peaks in workload and making an FT VM practical for use with Exchange Server 2007.

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