Quick way to disable IPv6 – Debian Squeeze (6)

echo "# Disable IPv6" >> /etc/sysctl.conf
echo "net.ipv6.conf.all.disable_ipv6 = 1" >> /etc/sysctl.conf
echo "#" >> /etc/sysctl.conf

Oh yeah, and if exim freaks out,
vi /etc/exim4/update-exim4.conf.conf
and change dc_local_interfaces so it reads

VMware Performance Tuning : Disabling System Restore in Windows Guests

Snapshots are available with VMware Workstation, VMware Fusion, VMware Server and ESX/ESXi.

Windows has a feature called system restore.  The idea behind System Restore is to revert to a point in history in case something goes wrong – i.e.: patch Tuesday. It’s an undo feature for your Windows OS. There is overhead for this undo feature, especially on the IO front which is generally acceptable for a dedicated desktop but not ideal for VMs.

One can approximate the function of System Restore with snapshots. Snapshots should be used only when modifying a VM, i.e. patch Tuesday, new software, etc… The idea is “I know I’m making a change so I snapshot the VM”, I execute the change, and test. Once testing reveals no issues and everything works as expected, the snapshot is removed.  (Of course this is now a manual process instead of an auto magic one so it’s a compromise)

Snapshots should not be persistent! They should only have a life of a few hours to a few days.  It is important to remove the snapshots since it creates a delta VMDK file and can grow quite large.  Also, if one creates many snapshots this can affect performance of the guest.

Personally I usually snapshot when the guest is powered down – this gives me the cleanest possible snapshot and I can revert to it with confidence.   It also means the snapshot is created instantly since the file system does not need to be quiesced.  Additionally, it is important to remember your VMware hypervisor can quiesce the file system (so long as VMware tools installed) but not necessarily the applications running in Windows.  i.e.:  SQL cannot be snapshotted reliably.

It is also very important to remember Snapshots are not backups in anyway shape or form. For “backup” purposes the entire VM package should be copied and compressed and stored on a medium other that the host running the VM.  i.e.:  I store my VM archives on my DIY NAS.

Disabling System Restore in XP: Right-Click My Computer and select properties and click the system restore tab, Select “Turn off System Restore” and click OK.
Disabling System Restore in Windows 7: Right-Click My Computer and select properties, click the System Protection link, Click the Configure Button and select “Turn off system Protection”, OK, OK

In conclusion, one can use snapshots in lieu of system restore to gain some performance in the Windows guest but it’s a compromise since the taking and deleting of snapshots is a manual process.

We got a robot – a Roomba 530

Sometimes you get an idea, Canadian Tire has a sale and tada you have a brand new Roomba to play with.  In this case a Roomba 530.  The Roomba has been very well documented and there are plenty of reviews out there so I’m not going to do that here.

With a 16 month old & a cat running around the house, there is little time to clean most days and it doesn’t take long till the main floor gets full of crumbs, Cheerios and  assorted pet bits.  It’s still early days but our Roomba has been able to clean up very well after our little monsters and with significantly less effort than pulling out the hose for the central Vacuum.  It’s even been profitable as it has some loose change in its dust bin this morning.
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iPod Touch stand from LTO case

In a moment of not doing what I should be doing I decided I needed a stand for my iPod Touch so I could watch some video I had recently loaded on it.  What to use?

As luck would have it I had an old LTO-4 case sitting on my desk destined for the recycle bin.  30 minutes later and most of the LTO case is in the recycle bin, I have an iPod Touch stand and I no longer have a spare moment to watch that video.

This is not exactly stellar work but it is fairly acceptable considering I was working with scissors and dull side cutters.  Not stellar but effective.