[gentoo-user] Linux Cluster

[gentoo-user] Linux Cluster

[Bruno Lustosa]

Hello, list.

I'm searching for a good cluster solution. What I need:

- Distributed filesystem, so that all machines can share the same
filesystem. Something like RAID-over-ethernet.
- Load balancing. Tasks should migrate between nodes.
- Redundancy, so that the death of a machine doesn't take the cluster
or any processes down.

I've been looking at some projects, but still didn't find what I need.
OpenMosix is good, however it still requires a 2.4 kernel, and it will
not offer redundancy (if a node crashes, the migrated processes are
lost).

So, anyone doing linux clusters?

-- 
Bruno Lustosa <bruno@lustosa.net>
http://www.lustosa.net/

-- 
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Re: [gentoo-user] Linux Cluster

[Jeremy Olexa]

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Bruno Lustosa wrote:
> Hello, list.
> 
> I'm searching for a good cluster solution. What I need:
> 
> - Distributed filesystem, so that all machines can share the same
> filesystem. Something like RAID-over-ethernet.
> - Load balancing. Tasks should migrate between nodes.
> - Redundancy, so that the death of a machine doesn't take the cluster
> or any processes down.
> 
> I've been looking at some projects, but still didn't find what I need.
> OpenMosix is good, however it still requires a 2.4 kernel, and it will
> not offer redundancy (if a node crashes, the migrated processes are
> lost).
> 
> So, anyone doing linux clusters?
> 

Sorry but you won't find much help on this list. Maybe this will help:

http://news.gmane.org/gmane.linux.gentoo.cluster

- --
Jeremy Olexa
(olexa@cs.umn.edu)
Office: EE/CS 1-201
CS/IT Systems Staff
University of Minnesota

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Re: [gentoo-user] Linux Cluster

[Boyd Stephen Smith Jr.]

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On Thursday 25 May 2006 14:13, "Bruno Lustosa" <bruno.lists@gmail.com> 
wrote about '[gentoo-user] Linux Cluster':
> - Distributed filesystem, so that all machines can share the same
> filesystem. Something like RAID-over-ethernet.

You probably want RH's GFS (there are probably other cluster-aware 
filesystems available for linux that I'm not aware of) and some sort of 
external storage that allows you to hook two machines to it.  You might 
also look into multipathing, that would help in case of a cable failure.

For maximum availability, you want your enclosure to have two scsi disk 
controllers, each with two separate scsi ports (these ports are on 
different chains).  You'll hook each of the two computers into cluster to 
one port on each controller and then use multipathing to tell linux both 
scsi paths are the same device.  You'll have a second external storage 
connected the same way and software use software mirroring.  Then, 
partition the mirror set (you could also partition at the external 
storage, but then you have to update the partitions on each storage) and 
lay GFS down.

At this point, you don't lose connectivity to your storage if a cable, an 
hba, an enclosure, a controller, or a computer goes down.  Of course, the 
controllers will handle RAID 5 or RAID 6 so you won't lose even a single 
path in case of HD failure.  GFS should allow concurrent access -- 
possibly even with multiple r/w mounts.  ext2/3, jfs, xfs, reiserfs, and 
even reiser4 are not cluster aware so they will only work properly in the 
configuration with multiple r/o mounts *OR* a single r/w mount.

> - Load balancing. Tasks should migrate between nodes.

HP's ServiceGuard for linux is the only software I know that will do this 
(for this *sure* there are other commerical solutions), and there is still 
some small amount of downtime when a task migrates, so they aren't 
automatically generated.

Also, some software (IIRC, WebLogic) is able to exist in a clustered 
environment with some method to sync state across individual nodes 
(possibly using the clustered FS) so that instead of 
jobs/packages/daemons/tasks migrating it just runs on all nodes all the 
time.

The second option (a cluster-aware program) is usually preferable, because 
the program itself is better at determining what state needs to be shared, 
so you get less intra-node communication and less downtime in case a node 
fails.  *However*, an external failover/load-balancer may either be your 
only solution (if you are already attached to a certain, non-cluster-aware 
program) or provide better behavior in the case the program is buggy 
(especially if it's failure mode corrupts and/or brings down other nodes).

> - Redundancy, so that the death of a machine doesn't take the cluster
> or any processes down.

I believe there's a userland implementation of the CARP protocol that may 
work for linux.  It allows 2 (or more) machines on the same network to 
share an IP and failover and/or load-balance handling packets directed to 
that IP.

> So, anyone doing linux clusters?

Not personally, but I was looking into them some during my last job.  
(Trying to get a customer to switch to linux.)

-- 
"If there's one thing we've established over the years,
it's that the vast majority of our users don't have the slightest
clue what's best for them in terms of package stability."
-- Gentoo Developer Ciaran McCreesh

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