the birdhouse in my soul

Your Linux runs on a VMware VM, but which ESX version is it ? You can see for yourself (as already explained in an earlier post on this blog). Run "dmidecode" and look at lines 10, 11 and 12. The list has been updated with current info: ESX 2.5 - BIOS Release Date: 04/21/2004 - Address 0xE8480 - Size 97152 bytes ESX 3.0 - BIOS Release Date: 04/17/2006 - Address 0xE7C70 - Size 99216 bytes ESX 3.5 - BIOS Release Date: 01/30/2008 - Address 0xE7910 - Size 100080 bytes ESX 4 - BIOS Release Date: 08/15/2008 - Address 0xEA6C0 - Size 88384 bytes ESX 4U1 - BIOS Release Date: 09/22/2009 - Address 0xEA550 - Size 88752 bytes

ICT website Computable runs a series of articles on Linux. The first article focuses on "hidden costs when migrating to Linux". In my experience, any project has hidden costs, and certainly so if preparation hasn't been done thoroughly, and with the necessary experience and know-how. There's plenty of experience available from various consultancy providers, use it ! PS don't forget to read the comments below the article as well.

Red Hat announced in december 2009 that RHEL support for Intel Itanium was being dropped. On april 2nd, Microsoft announced that Windows 2008 R2 was going to be the last Windows version to support the Itanium platform. A chronicle of a death foretold...

I don't know what got me to search for new firmware for my Linksys (now Cisco) SLM2024. But I did, and found version 2.0.0.8 (upgrade from the previous 1.0.1). Aside from the web interface, there's no obvious changes. It is now branded Cisco, rather than Linksys. But the most important change for me wasn't in the release notes: I can now manage my gigabit switch using Firefox ! (tested with Firefox 3.6.2 on Windows)

Red Hat and related distro's (like CentOS) use 1000 timer interrupts per second, per CPU core or thread (this is called the "HZ value" inside the kernel). Because this causes a lot of extra work in case of virtualization, and caused (past tense since RHEL 5.4!) problems with timekeeping, the " divider " kernel parameter has been introduced. For example, by booting with "divider=10", the kernel uses 100 timer interrupts instead of 1000, and "divider=25" means 40 timer interrupts per second. I did a little test today to see what difference that makes when running CentOS5.4 on vSphere. Tests were done with the current 2.6.18-164.11.1.el5 x86_64 kernel in a single vCPU VM. These are the results from my test environment: standard settings: HZ=1000: 60 MHz cycles used when idle. divider=2: HZ=500: 36 MHz cycles used when idle. divider=5: HZ=200: 25 MHz cycles used when idle. divider=10: HZ=100: 20 MHz cycles used when idle. divider=25: HZ=40: a...

My Volkswagen car has the "universal cellphone preparation" UHV built-in. This is the main part of a car kit, but requires an additional adapter for connecting to a cellphone. At first, I was using an adapter for my good old Nokia 6310, even after I changed to the Nokia E71. Connecting was easy: pair the phone with the "VW UHV" bluetooth entity, and done. This has the phone connected to the car kit at all times, so even non-call-related functions use the car audio system (e.g. voice recognition). But progress will have its way, no matter what happens. So in comes the "bluetooth touch adapter". Instead of a phone-specific adapter, this is a small touchscreen device that slots into the UHV dashboard mount. Connecting a phone is very different now: the Bluetooth Touch Adapter connects to the "VW UHV" device via bluetooth the phone connects to "Touch Adapter" device, also via bluetooth The device doesn't allow step 2 if step 1 didn'...

VMware and disk-array based thin provisioning can help you economize on disk space, just as disk-array based deduplication can. But how to take optimal advantage of those techniques ? Executive summary: dd if=/dev/zero of=/tmp/tempfile.zeroes ; rm -f /tmp/tempfile.zeroes First of all, both thin provisioning and deduplication work transparently. But you can make them work better with a little bit of work. There's three different types of blocks on your (virtual) disk that we need to distinguish: data blocks, old data blocks, and empty blocks. Data blocks and empty blocks are what they are, and can't be influenced. Data blocks contain data for files that are on your filesystem. Empty blocks are empty, have never been written to with any real data, so their blank, contain only zeroes. It's the "old data" blocks that we can improve: they contain data that used to be part of a file. The file got deleted, but the contents are still there. Overwriting those blocks with z...