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List:       gfs-devel
Subject:    Re: GFS locking info over (serial) cable
From:       David Brower <dbrower () us ! oracle ! com>
Date:       2000-07-27 17:57:55
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I don't se how hardware dmep is fastest, since there is no hardware
dmep available right now, is there?  The simplest/fastest solution
is the second one -- plug an additional NIC into each machine and
form a private network.  You don't even need a hub/switch in this
configuration, just a crossover cable or thin-net coax and a terminator.

I'd be concerned that a vanilla serial line would have enough bandwidth
and low latency for lock messaging.  Of course, the demand is specific
to the disk access pattern of the applications on the machines in question.

-dB

Tim Riker wrote:
> 
> The fastest solution would be hardware DMEP, but the next choice would
> be to create a private network between the nodes with ethernet. This
> network would be secure. Then assign additional (probably non-routable,
> like 192.168.0.x) addresses to each node. If you only have two nodes,
> you could even use a twisted ethernet cable for this.
> 
> Of course a serial cable with ppp would work as well, but I'd recommend
> the 2nd ethernet NIC approach.
> 
> If you have fibre channel cards that support ethernet packets as well
> (like the Emulex LightPulse LP8000) you could use the fibre-channel IP
> network and not need any additional hardware. I have not set up this
> type of configuration, but it should be possible. Anyone else done this?
> Of course if you are using SCSI, this would not be an option. (well, a
> very difficult option anyway... in theory IP over SCSI is possible but
> dual initiators is not very well supported by Linux drivers and there is
> no existing IP over SCSI implementation that I'm aware of ;-)
> 
> Andrew Barry wrote:
> >
> > dlock is supported by some hardware, but is no longer usable for GFS
> > locking. We are in the process of finalizing our spec for the new DMEP
> > spec. (see a draft on the GFS web page)
> >
> > However, GFS needs an ip connection to issue callbacks to other nodes.
> > There is no reason this traffic couldn't go over a serial cable, just use
> > ppp.
> >
> > Andrew Barry
> > barry@sistina.com
> >
> > On Wed, 26 Jul 2000, Sander Verbruggen wrote:
> >
> > > Hello developers,
> > >
> > > I'm helping setting up a network for a customer. There is one problem:
> > > they want absolute security regarding their network. For this, they
> > > don't want IP traffic between two of there machines, but these machines
> > > SHOULD share a common disk array/cabinet.
> > >
> > > >From the documentation on your site, I know you are developing the DLock
> > > command, but because this not yet finished, this is no option to them.
> > > As far as I deducted, you use IP to mainly negotiate locks between
> > > servers (please correct me if I'm wrong). Is it possible to send this
> > > information over another line, for example a serial cable which connects
> > > the two machines?
> > >
> > > Background:
> > > Their idea is: set up two machines, both of them RedHat 6.2 development
> > > servers. Connect them both to one disk cabinet to let them share the
> > > same source-files. The reason why they want security, is that their
> > > internal network is connected a global network which is highly secured.
> > > Several people however use ISDN routers to connect to the (same)
> > > development site. However, no external IP packets are allowed on the
> > > secure network. And even firewalls can be hacked, so first option is to
> > > go with the above; no network traffic between the two machines, but
> > > still a shared development environment.
> > >
> > > If someone could please let me know, if this is a solution worth
> > > checking out or even implementing, please let me know as soon as
> > > possible.
> > >
> > > Greetings,
> > > Sander Verbruggen
> > >
> > > --
> > > Sander Verbruggen
> > > Ordina Integrity BV
> > > the Netherlands
> > > --
> > >
> > > S.Verbruggen@bigfoot.com
> 
> --
> Tim Riker - http://rikers.org/ - short SIGs! <g>
> All I need to know I could have learned in Kindergarten
> ... if I'd just been paying attention.
> 
> -
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-- 
Butterflies tell me to say:
"The statements and opinions expressed here are my own and do not necessarily 
  represent those of Oracle Corporation."

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