[lug] High Availability and Load Balancing Linux?

[Alan Robertson]

Peter Hutnick wrote:
> Richard Heintze said:
> 
>>Does Linux support failover on Dual ported RAID?
>>Does Linux support load balancing with two nodes
>>connected to a dual ported RAID? I believe it needs a
>>distributed lock manager to do this. Does it have one?
> 
> 
> First, please see http://hutnick.com/writings/goodsubject.html.  Replying
> to a digest is super un-helpful.
> 
> To generally answer your questions:
> 
> Hardware RAID is only dependent on the OS in terms of drivers.  If there
> is a driver all of the RAID controller's features should work as expected.
> 
> Linux includes a complete set of software RAID features.  See
> http://en.tldp.org/HOWTO/Software-RAID-HOWTO.html.
> 
> There are some HA and load balancing packages.  See
> http://www.google.com/search?hl=en&lr=&ie=UTF-8&q=high+availability+linux&spell=1
> and
> http://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=load+balancing+linux&btnG=Google+Search
> for HA and load balancing info.
> 
> You might notice that it is very easy to find this sort of info by typing
> a few key words into google.  As another example, I found the above LDP
> link to the Software RAID HOWTO here
> http://www.google.com/search?hl=en&ie=ISO-8859-1&q=linux+software+raid+howto&btnG=Google+Search


The most common load balancing method used is the Linux Virtual Server 
project.  The kernel portion of the LVS software is called ipvs and is 
standard on every 2.4 kernel.

The oldest and most flexible HA project on Linux is called linux-ha.  For 
various reasons, the software is called heartbeat.  Since I'm the project 
leader, and primary author, I tend to like it a lot ;-)  You can read about 
LVS and Linux-HA at http://linux-ha.org/.  The heartbeat software can be 
found in the download directory: http://linux-ha.org/download/

We're just about to put out a point release (this week) called 1.0.2.  This 
(well-tested) prerelease version is in the download directory:

   heartbeat-1.0.2pre-1.i386.rpm  heartbeat-ldirectord-1.0.2pre-1.i386.rpm
   heartbeat-1.0.2pre-1.src.rpm   heartbeat-pils-1.0.2pre-1.i386.rpm
   heartbeat-1.0.2pre.tar.gz      heartbeat-stonith-1.0.2pre-1.i386.rpm

By well-tested, I mean that we did over 5000 failovers for this minor point 
release.

Linux-HA and LVS software are packaged together as "UltraMonkey".  horms 
will be putting out a new version of ultramonkey in a few days too.



	-- Alan Robertson
	   alanr at unix.sh




-- 
     Alan Robertson <alanr at unix.sh>

"Openness is the foundation and preservative of friendship....  Let me claim 
from you at all times your undisguised opinions." - William Wilberforce