huh?

New PC time! Hooray!

Oh wait… permission denied on accessing my old NTFS formatted drives I’ve moved to the new PC. Google to the rescue with this:

1. Run “cmd” as Administrator

2. Go to the drive or folder in question, for example:

CD /D D:

3. To reset all the files permissions, type:

icacls * /T /Q /C /RESET

4. And that’s it!

After that, the files permissions were reset and I could access them back again.

cacls is a handy tool to change permissions of files en masse.

Reference: http://support.microsoft.com/kb/318754

from: http://lallousx86.wordpress.com/2009/06/14/resetting-ntfs-files-security-and-permission-in-windows-7/

Oh god. That took far too long. A while back the kids laptop internet access stopped working. I had a quick look at it and found it was doing something weird and rejecting DHCP leases from my Cisco 877W over wifi.

Figuring it would be some exotic driver/software incompatibility I left it alone. Until today I went to use my shiney new Windows 7 work laptop. And hit the exact same issue.

Some googling later, I find I’m not alone. Many people are having similar issues, though with no consistent “fix”. Spending some more time on this, I found the cause of my specific issue. God damn proxy-arp. I hadn’t set “no ip proxy-arp” under the dot11radio interface on my 877W, so of course when Windows 7 clients performed a gratuitous ARP on their assigned lease, they would ALWAYS get a response. In turn they’d reject the address and request another. The router would flag the address as bad and hand the laptop the next address. Rinse and repeat.

Lesson learnt: turn proxy-arp the hell off on EVERY layer 3 interface. I knew this already, but seeing as I didn’t have it set I got bit.

After a few snags, my mail VM is now happily running under virtualbox 3.0.8 on a Debian 5 host.

The last issue I’ve resolved was related to high sy% cpu usage that I took me a while to figure out. Top showed sy% at around 20% constantly, this used to be 6-7% at most. Googling didn’t give me any useful results. After looking into other issues I found a forum post by someone mentioning that by default, VMware enables emulation of something called an IO APIC. Virtualbox doesn’t, as it introduces extra overheads.

With nothing to lose, I’ve enabled this on my virtualbox vm with “VBoxManage modifyvm “vm-name” –ioapic on”, and restarted the VM. So far so good. CPU use is back to decent levels, a little higher than before, but I can live with it. CPU time is cheap. As an added bonus the VM is now picking up both CPU cores I had it configured with.

Other gotchas I’ve encountered:
- moving from VMware to Virtualbox, the NIC type emulated changes. So I had to remove the udev interface numbering scheme….
- but first I had to manually enable the NIC with VBoxManage
-the virtual hard drive file from the old VMware host was 200gig, as I’d pre-allocated it all. For the migration I shrank it by doing a vm-vm migration using the VMware convertor. Problem being, the resulting file is far larger than the actual used space in the file. 11gig used, but the file ended up being over 70gig. My theory is that 70gig is the largest the volume ever grew to, so the convertor wouldn’t shrink it any more.

I hope this is of use to someone out there in Google-land.