questions on tuning PE for linux and SAN on linux..

Arjan van de Ven arjanv at
Mon Mar 25 03:17:01 CST 2002

On Mon, Mar 25, 2002 at 06:52:07PM +1000, jason andrade wrote:
> On Mon, 25 Mar 2002, Arjan van de Ven wrote:
> > Michael E Brown wrote:
> > 
> > > Sounds like you want GFS: It is a commercial
> > > product that you will have to pay for if you want. There is an open source
> > > version: if you want to investigate.
> > 
> > GFS is too crappy to be worth any money. Trust me; we tried to fix it in
> > OpenGFS 
> > but the entire design is just beyond hope.
> > 
> so what are people doing for SAN under linux apart from GFS ?
> i can imagine it's not that difficult when you want to just use a SAN to provide
> a central disk store to a bunch of different servers (zone/lun masking in the
> switch?) 

This can indeed be done

> but what happens when you want "real" redundancy and want to connect
> the same luns to multiple linux boxes ?

Unfortionatly there's no real solution for this in linux
currently. Several companies will happily flog you a binary only
module for lots of $$$ that claims to do this but they you're stuck with
whatever exact kernel they support, and often those modules just don't
work well in the first place. (I could name names but I better not)

> i am trying to look at linux/san to get some higher redundancy (by decoupling
> storage away from the OS) and better throughput (fibrechannel/raid), without
> going all the way down the "we have a mission critical database/whatever" track.

the io fencing scheme is doable right now... so if you don't need to share
the disk data that works. What will also work is having 2 NFS servers in
HA mode in front of the array (eg only one can access the luns at a
time but if it falls over the second one "takes" the
luns and continues serving NFS)

    Arjan van de Ven

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