[TriLUG] Linux Clustering (high availability) and file systems

[Ed Hill]

On Tue, 2004-04-27 at 14:42, Tarus Balog wrote:
> Gang:
> 
> Okay, I want to make a particular file system highly available.
> 
> For example, suppose, just suppose, I had a directory called  
> "/var/opennms" that I wanted multiple machines to be able to write to.  
> So if I had two active machines writing to that file system, and one  
> died, I'd have a third machine that could come on-line and pick up  
> where the failed machine left off.
> 
> It has to be fast and reliable (so nothing like NFS). Has anyone worked  
> with SAN equipment where we could dual attach two or more machines over  
> SCSI or Fiber Channel?
> 
> How do Linux Clusters handle making data highly available.
> 
> Relevant links and RTFM suggestions welcome.


Hi Tarus,

I'm a "performance guy" (scientific computing), not a "high availability
guy", so please take these comments with a grain of salt.

Our Linux clusters, and in fact the majority of the Linux/Unix clusters
I work on use NFS.  And yes, NFS implementations on Linux have been
somewhat flaky in the past but the situation is much better these days. 
We're using them on a 24/7 basis and have many more problems from "other
things" (eg. hw failures, power outages) than true NFS problems.

In any case, commercial alternatives include:

  Sistina:
    http://www.sistina.com/home.html

  IBM's GPFS:
    http://www-1.ibm.com/servers/eserver/clusters/software/gpfs.html

and, AFAIK, Coda and InterMezzo aren't "there yet" and OpenAFS is only
available for older kernels.

Good luck!
Ed

-- 
Edward H. Hill III, PhD
office:  MIT Dept. of EAPS;  Rm 54-1424;  77 Massachusetts Ave.
             Cambridge, MA 02139-4307
emails:  eh3 at mit.edu                ed at eh3.com
URLs:    http://web.mit.edu/eh3/    http://eh3.com/
phone:   617-253-0098
fax:     617-253-4464
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