[Linux-cluster] Simplest 4 node GFS 6.1 cluster

[Troy Dawson]

Hello,
I've really been trying to figure this out from the documentation, and 
if it's in there, please point me at it.

Here is what I want to do.  I have 4 machines, all connected to the same 
SAN disk.  1 machine will be the only machine that can read and write to 
the disk.  The other 3 will be read only.  The read only machines will 
be the only ones that have outside services running, such as ftp, nfs, 
rsync.

I don't have a reliable 5th machine.  So I don't have a way to do an 
external lock manager.

I don't want any failover, but I also don't want a single point of 
failure.  Basically if one of the read only machines goes dead, then 
it's dead, nothing takes it's place, but the other machines can go right 
on working.  If the read, write machine goes dead, then it's dead, but 
the read only machines can go right on doing what they normally do.  And 
if two or three machines die, I still want the one to still be able to 
at least read the data.

This idea of fencing is what's throwing me off.  If I'm reading things 
right, I can't do group GFS without them being in a cluster, and they 
can't be in a cluster without doing fencing.  But the fencing seems to 
just allow the various machines to take over for one another.

I also don't have access to the SAN switch, other than my machines plug 
into it.  It's essentially a black box.  These machines also don't have 
any way to remotely turn power on an off.

Is GFS what I really want?  I've tried just standard ext3, but I was 
getting a caching problem with my read only machines.  Do I just want to 
try and fix my caching problem?

Troy Dawson
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Troy Dawson  dawson at fnal.gov  (630)840-6468
Fermilab  ComputingDivision/CSS  CSI Group
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