The 2.6.33 Linux kernel has introduced a useful new service called the DRBD – Distributed Replicated Block Device. This service mirrors an entire block device to another networked host during run time, permitting the development of high-availability clusters for block data. Explore the ideas behind the DRBD and its implementation in the Linux kernel.
I’ve had this working in 2.6.18.xxx since RHEL 5.0 came out. It was available earlier but the heartbeat bits before then were particularly flaky.
finally, it has made it into the kernel.
That is worthy of the article, but the tech? Nah. It is old hat with many HPC admins.
The result is that it will be easier for those who need it to implement it. By a whopping half hour IMHO.
Are you a programmer ? Keeping patches up to date with changing code can be very timeconsuming.
The kernel the fastest changing large piece of software (that is on public display that we know of) in the world.
Good luck with that.
Yeah I’m a programmer. I wrote my first program in 1972 using Fortran on Punched Cards which were processed by an ICL1901. Now I write in C++, PHP, Python, SQL & Bash (most of the time)
So you think patches are a problem?
All the system’s I’ve used DRBD on are back end servers. They are not web facing. They get patched maybe once every three months and only when they have been fully tested in our lab environment.
Ironically we are updating four of the DRBD systems this weekend.
The RPMs are held in a local YUM repository. Buy some freak of nature there is also a repo that holds all our ‘site developed stuff’. This also includes the pre-built DRBD components including heartbeat and the configs for everything. They will be applied at the same time.
Fast forward to say 18 months time when be may be moving to RHEL 6.x. We will have sorted out all the dependencies and updated our scripts so that when we decide to upgrade the Kernel from 2.6.18-nnn nothing will break.
Oh, did I say that we have 15 rising to 18 DRBD Systems all deployed this way? Most of them run Oracle as well.
This is not a desktop or laptop environment you know.
Most of the systems are in a Lights out DataCentre somewhere in Colorado. I’m in England.
Enough said.
Back to watching the scripts execute with one eye on the Cricket.
Ah, so you’re a newbie then.