[ale] OCFS2

[Christopher Fowler]

One idea is that the 2nd server does not mount its /dev/sda2 until the
first server dies.  That way you don't really have 2 OS's access the
same data.

I can purchase a Cordata EATA device but there is still a single point
of failure.

On Mon, 2006-03-20 at 13:36 -0500, Jeff Hubbs wrote:
> I perhaps should have followed the situation more closely in the past 
> couple-odd years, but you're alluding to a level of fault tolerance 
> that's not easy to hit, at least not at Free Software prices.
> 
> Both the operating system and the app have to be able to cooperate with 
> such a scheme - that's where the trouble comes in.  In c. 2000, 
> TurboLinux' own clustering white papers proposed using Oracle on Solaris 
> for such.  MS SQL Server on the appropriate "edition" of Win2K5 is 
> probably another option; IIRC, it uses a main/auxiliary model for 
> service failover.  I doubt if either scheme will operate without some 
> sort of burp on failover, even if all that's felt is a delay. 
> 
> Having more than one OS instance access the same disks at once is one of 
> the things that VMS had game on 20 years ago, and it's still available 
> although running it in practice seems to be like threading a needle with 
> an ever-shrinking eye.
> 
> Christopher Fowler wrote:
> 
> >On Mon, 2006-03-20 at 11:46 -0500, Chris Ricker wrote:
> >  
> >
> >>On Mon, 20 Mar 2006, Christopher Fowler wrote:
> >>
> >>    
> >>
> >>>http://lwn.net/Articles/137278/
> >>>
> >>>Could I use OCFS2 to cluster 2+ servers that are running MySQL so if one
> >>>goes down the other could simply jump in its place?
> >>>
> >>>What I like about this idea is that instead of using a central RAID
> >>>cabinet that could die both boxes could simple share the same /opt/RUN
> >>>file system.  The backups could simply have mysql turned off an then a
> >>>script could turn it on.  
> >>>      
> >>>
> >>You should be able to. Note that OCFS2, unless things have changed, 
> >>requires physically shared storage - two hosts sharing the same LUNs from 
> >>a SAN or similar
> >>
> >>    
> >>
> >
> >Oh.  I guess I was looking more of where 2 servers do RAID1 together.
> >
> >server1:/dev/sda2 and server2:/dev/sda2 are mirrored so that either one
> >could have access to the files in case the other dies.
> >
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