Debian Sarge from VMWare to Xen DomU

Now I have a good Gentoo Xen instance, I want to migrate my VMWare environments to Xen DomU's.

My mobo is the Via Epia EN12000 with a Via C7 Esther CPU, and only has the cmov CPU flag, so no chance of getting HVN working. I had to build the standard Gentoo Xen Linux Sources at version 2.6.20. That's better than the stock Xen Kernel which is currently 2.6.18, but it still doesn't have specific support for the Via C7. Not a problem though.

I have an old Debian Sarge that hasn't been updated in a while. To get it working I had to add the sarge-backports source to /etc/apt/sources.list. Once that was done it was still a bit of a problem getting a Xen kernel installed. In the end I figured out the dependencies to work.

Aptitude didn't give very helpful details so I had to get the info I needed by using "dpkg -i" on packages. Eventually the following commands got me where I wanted to get:

aptitude install klibc-utils
aptitude -V -f install udev=0.105-4~bpo.1
aptitude -V -f install initramfs-tools
aptitude -V -f install linux-image-2.6-xen-686

The key to this seems to have been the packages removed and installed by klibc-utils. After that you could probably skip to installing linux-image-2.6-xen-686.

For reference, the main error from aptitude that was killing me was:

The following packages have unmet dependencies:
 initramfs-tools: Depends: udev (>= 0.086-1) but it is not installable

even though udev-0.105-4~bpo.1 was installed.

Once the kernels were installed I tried to boot the domain in Xen and faced another problem. The linux-image-2.6.18-4-xen-686 in Sarge Backports now supports PAE, so I had to rebuild my dom0 kernel and apps-emulation/xen with PAE support.

Creating a filesystem on a RAID array

I have a linux software RAID5 array. I want to make sure I create an optimized filesystem on the array.

The array details are:

# mdadm --misc -D /dev/md3
/dev/md3:
        Version : 00.90.03
  Creation Time : Sat Oct 21 19:32:23 2006
     Raid Level : raid5
     Array Size : 735334848 (701.27 GiB 752.98 GB)
  Used Dev Size : 245111616 (233.76 GiB 250.99 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 3
    Persistence : Superblock is persistent

    Update Time : Tue Sep 11 19:18:42 2007
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 6f6b9978:683a7ada:109f3c19:b8abb3ae
         Events : 0.53048

    Number   Major   Minor   RaidDevice State
       0       8       49        0      active sync   /dev/sdd1
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1
       3       8        1        3      active sync   /dev/sda1

Here we see a Chunk Size of 64K and 4 disks in the array.

Based on the information in this discussion thread, this means that the stride is 16 based on a Chunk Size of 64k accross 4 disks with a filesystem with a 4k block size.

So a good mkfs.ext3 command would be

mkfs.ext3 -b 4096 -E stride=16 /dev/vg/lvol01

Gentoo GCC-3.3.6 and mplayer or xine

Got a new VIA EPIA EN12000E mobo over the weekend and plan to set it up as a set top box and file server, among other things. It's a pretty nifty little gadget and best of all has no fan.

I'm building a new gentoo instance on it. So far I've built the core OS on a mirror RAID pair of drives and plan to move 4 SATA drives to it when all the services are completely built and it works with my 1080i HDTV. For now I'll probably just stick to using the VGA interface, hoping that'll be easiest.

I've had a few hurdles to get through during the build. For example, I wanted to do a network boot and install, but the gentoo network boot and install instructions weren't clear. So I reverted to an Ubuntu network boot I set up a while ago and went through the rescue interface.

I set up a RAID1 pair for the root partition, and LVM over RAID1 for a few other partitions. Considering my first gentoo installation is still going strong since being built in 2002, I figure I'll make sure this one lasts too.

It took a while to get going. I generally remember how to get started with the gentoo install since I started doing it years ago when we would start from stage1 (if fanatic enough). Unfortunately the Ubuntu 7.04 rescue boot doesn't provide SSHD so I had to get the stage3 and portage installed and chrooted before I could get SSH to the box.

Once that was done I tweaked the CFLAGS and USE flags for the hardware and did the bootstrap.sh to make sure it's fully optimized for the hardware. I then built a custom kernel (2.6.22.6) to enable most of the embeded hardware that I'll be using to start with.

When I booted the new kernel none of the LVM partitions mounted. Duh! I forgot to emerge the lvm2 package. Luckily LVM was compiled in the kernel, so I just copied the static vgscan and vgchange binaries from my other box and started the LVM partitions up.

Next I diff'd the /var/lib/portage/world file to see what I want from my old box and started working through the USE flags. I noticed a dependancy for gcc-3.3.6. The core system already came with gcc-4.1.2 so why should i put an old gcc-3 on it? It turns out that all that is needed is to 'emerge libstdc++-v3'. Note that the package is not simply libstc++.

I'm not sure why libstdc++-v3 isn't included in the 2007.0 stages since they're packaged with gcc-4. I eventually found the answer on an IRC log (http://dbforms.oxxus.net/dependency-question-appemulationwine-world-corefonts/index.php), which references the Gentoo GCC Upgrade Guide.

Next I have ccache and distcc set up to speed up the builds and I must wait a couple of days for everything to install. I hope the configs won't be too complicated and I'm looking forward to seeing the performance of this system.