Tag: ubuntu

BlackBerry tether with Ubuntu 9.10

There are many pages out there about how to use a tethered BlackBerry internet connection with Ubuntu 9.10. Here is one that actually works. It uses Barry, BlackBerry support software generously provided by Net Direct Inc.

I’ve found this quite useful with an Ubuntu based netbook. There is Wifi a lot of places, but not even close to “everywhere”.

My BlackBerry is on the T-Mobile network, which (nicely) includes tethering at no extra cost, but (not so nicely) offers only EDGE (not 3G) in most of the US. Still, in a pinch an EDGE connection is far better than no connection, and is quite suitable for occasional use at zero incremental cost. For heavy mobile wireless tethering users, I suggest Verizon or Sprint service with their respective USB dongles.

gitosis on Ubuntu 9.04 Jaunty

As of April 2009, the gitosis package in Ubuntu 9.04 Jaunty is broken; it fails with an error like so:

pkg_resources.DistributionNotFound: gitosis==0.2

There are quite a few pages and mailing list messages that mention this. I only found one with a good hint toward a solution, which was that it is also a known issue on Debian. Following that lead, I got it working by grabbing newer packages from Debian Unstable:

wget http://ftp.us.debian.org/debian/pool/main/p/python-support/python-support_1.0.2_all.deb
wget http://ftp.us.debian.org/debian/pool/main/g/gitosis/gitosis_0.2+20080825-14_all.deb
sudo dpkg -i python-support_1.0.2_all.deb
sudo dpkg -i gitosis_0.2+20080825-14_all.deb

Use this at your own risk; your mileage may vary.

DRBD on Ubuntu 8.04

A while back I wrote about setting up DRBD on Ubuntu.

It is considerably simpler now: you don’t need to build the module anymore, a reasonably recent version is already in the box. You should still read the full directions at the DRBD web site, but to get it going, you only need to configure it and start it; don’t download anything, don’t compile any modules kernels, etc.

Rather, the module is already there; you could load it manually like this:

modprobe drbd

But you really want the utils package:

apt-get install drbd8-utils

… which sets things up the rest of the way. Simply proceed with the configuration file, /etc/drbd.conf. If you want a nice clean config file, remove all the existing resource sections in the drbd.conf installed by the Ub package, and put in something like so:

resource kylesdrbd {
  protocol      C;

  startup { wfc-timeout 60; degr-wfc-timeout  120; }
  disk { on-io-error detach; }
  syncer {
  }
  on x1.kylecordes.com {
    device      /dev/drbd4;
    disk        /dev/sdb5;
    address     192.168.17.61:7791;
    meta-disk   /dev/sdb1[0];
  }
  on x2.kylecordes.com {
    device      /dev/drbd4;
    disk        /dev/sda5;
    address     192.168.17.62:7791;
    meta-disk   /dev/sda3[0];
  }
}

The hostnames here need to match the full, actual hostnames. I show my example disk configuration, you’ll need to do somethign locally appropriate, based on understanding the DRBD docs.

Also adjust the syncer section:

syncer {
rate 40M;  # the rate is in BYTES per second
}

If there was already a filesystem on the metadata partitions you’re trying to put under DRBD, you may need to clear it out:

dd if=/dev/zero of=/dev/sdb1 bs=1M count=1

Now you’re ready to fire it up; on both machines:

drbdadm create-md mwm
drbdadm attach mwm
drbdadm connect mwm

# see status:
cat /proc/drbd

You now are ready to make one primary; do this on only one machine of course:

drbdadm -- --overwrite-data-of-peer primary all

or

drbdadm -- --overwrite-data-of-peer primary kylesdrbd

In my case, I now see a resync starting in the /proc/drbd output.

You don’t need to wait for that to finish; go ahead and create a filesystem on /dev/drbd0.

It’s best to have a dedicated Gigabit-ethernet connection between the nodes; or for busy systems, a pair of bonded GigE. For testing though, running over your existing network is fine.

I found that an adjustment in the inittimeout setting helps to avoid long boot delays, if one of the two systems is down.

Of course I only covered DRBD here; typically in production you’d use it in conjuction with a failover/heartbeat mechanism, so that whatever resource you serve on the DRBD volume (database, NFS, etc.) cuts over to the other machine without intervention; there is plenty to read online about Linux high availability.

RocketModem Driver Source Package for Debian / Ubuntu

A couple of months ago I posted about using the current model Comtrol RocketModem IV with Debian / Ubuntu Linux. Ubuntu/Debian includes an older “rocket” module driver in-the-box, which works well for older RocketModem IV cards. But for the newest cards, it does not work at all. The current RocketModem IV is not recognized by the rocket module in-the-box in Linux, it requires an updated driver from Comtrol.

With some work (mostly outsourced to a Linux guru) I now present a source driver package for the 3.08 “beta” driver version (from the Comtrol FTP site):

comtrol-source_3.08_all.deb

Comtrol ships the driver source code under a GPL license, so unless I badly misunderstand, it’s totally OK for me to redistribute it here.

To install this, you follow the usual Debian driver-build-install process. The most obvious place to do so is on the hardware where you want to install it, but you can also use another machine the same distro version and Linux kernel version as your production hardware. Some of these commands must be run as root.

dpkg -i comtrol-source_3.08_all.deb
module-assistant build comtrol

This builds a .deb specific to the running kernel. When I ran it, the binary .deb landed here:

/usr/src/comtrol-module-2.6.22-14-server_3.08+2.6.22-14.52_amd64.deb

Copy to production hardware (if you are not already on it), then install:

dpkg -i /usr/src/comtrol-module-2.6.22-14-server_3.08+2.6.22-14.52_amd64.deb

and verify the module loads:

modprobe rocket

and finds the hardware:

ls /dev/ttyR*

To verify those devices really work (that they talk to the modems on your RocketModem card), Minicom is a convenient tool:

apt-get install minicom
minicom -s

Kernel Versions

Linux kernel module binaries are specific to the kernel version they are built for; this is an annoyance, but is not considered a bug (by Linus). Because of this, when you upgrade your kernel, you need to:

  • Uninstall the binary kernel module .deb you created above
  • Put in the new kernel
  • Build and install a new binary module package as above

Rebuilding the source .deb

Lastly, if you care to recreate the source .deb, you can do so by downloading the “source” for the source deb: comtrol-source_3.08.tar.gz then following a process roughly like so:

apt-get install module-assistant debhelper fakeroot
m-a prepare
tar xvf comtrol-source_3.08.tar.gz
cd comtrol-source
dpkg-buildpackage –rfakeroot

The comtrol subdirectory therein contains simply the content of Comtrol’s source driver download, and this is likely to work trivially with newer driver versions (3.09, etc.) when they appear.

DRBD on Ubuntu

This week I experimented with DRBD (Distributed Replicated Block Device) which is “a block device which is designed to build high availability clusters. This is done by mirroring a whole block device via (a dedicated) network. You could see it as a network raid-1.”

DRBD can be used for build a “poor man’s SAN”, a RAID running over Ethernet. In our case, we want a warm spare of an important database system, i.e. a second set of hardware which can take over for the primary within a few minutes of failure, and DRBD might be a great way accomplish that. DRBD runs on commodity hardware (ordinary servers, network adapters, etc.) so it is inexpensive. It is also, if benchmarks and comments are to be believed, surprisingly good. I suspect this is because CPUs and networks (Gigabit Ethernet, ideally) are so much faster than disks.

The systems at hand for testing here run the Ubuntu distribution, itself based on Debian. It took a lot of reading and learning, but very little actual typing, to get DRBD going on Ubuntu. My writeup here should help the next person along. As I write this, the released version of DRBD is 0.7, and the DRBD site encourages ignoring the newer unofficial release, advice that I followed.

First, read the HOWTO and the FAQ, but don’t follow the instruction in them yet; then you are ready to begin. The guessable part is to install the module with apt-get (you’ll need the “Community” APT sources in Ubuntu; I don’t know offhand what is equivalent in Debian):

apt-get install drbd0.7-module-source

This installs the module’s source code, not the module itself. After doing this, I spent a couple of hours trying to figure out how to compile it – untarring it and running “make” does not work. There is an abundance of confusing and misleading advice on the web about this, including advice to compile your own kernel. If you don’t need a custom-compiled kernel for other reasons, ignore all that and discover the joy of Debian’s “Module Assistant”, invoked by the command “m-a”.

m-a prepare

“prepare” will get your machine ready to compile modules that can link with the running kernel; it will prompt to download and install packages needed for this, including the correct kernel header packages. Now you are ready to build and install the module:

m-a a-i drbd0.7-module-source

Follow the prompts; if it asks to install more packages, agree to do so. On Ubuntu 6.10, it may fail with an error about “mv”. This is a known bug; the workaround is to expand the module source file (it lives in /usr/src/), add the line “SHELL=/bin/bash” at the top of each Makefile, then retar the module source.

By the way, this points out a stark and troubling aspect of Ubuntu “community” packages: not only are they not assured to work, they are not even casually tested to verify they compile on the Ubuntu version they are purportedly intended for use with… which I find very disappointing. I suppose the lesson is that Ubuntu is very slick for the set of officially supported packages, but if you’ll be using a lot of packages beyond that set, its appeal is much diminished.

Now you are ready to enable DRBD, following the HOWTO instructions, starting with setting up /etc/drbd.conf.

In my case I used LVM to make a 10 GB partition on each machine, put DRBD on top of that, put a filesystem (Reiserfs, for variety) on top of them, then moved/symlinked my PostgreSQL data there. It worked fine, including these tests: I started a long intensive DB operation (restoring a several-GB backup), then with that running, rebooted the secondary machine. This did not interrupt the DB operation, and when the secondary finished its reboot, the DRBD partition re-synced automatically. I then shut down the primary machine, and verified I could mount and read that same data on the secondary machine… all exactly as described.

One caveat though – in a few cases, machines with DRBD stopped during the boot sequence, waiting for user intervention (in this case, closing a shell) because they the DRBD device wouldn’t mount. I suspect this was because I don’t fully understand how to configure it.

Of course this was just a short initial look, but I am very impressed with DRBD so far.