Network RAM for Beowulf

James Alton jalton at olsh.cx
Thu Aug 16 12:36:21 PDT 2001


Would it be possible to bypass the entire, network a pile of PCs approach?
Instead, could you build a circuit board where you plug in a hoard of 512MB
PC133 sticks (oh so $30 cheap now), run the board at 133 or faster,
interface through the PCI slot or something faster? It would run almost
infinitely faster than going through an Ethernet port. It's too bad I don't
know enough about electronics to build such a beast myself. I only know
that's you'd have to run the board at memory speed, have some memory
controller, perhaps a board controller to interface to the gigantic memory
space, and some support hardware (capacitors and resistors here and there).
If you made it interface though PCI, I don't think there would be a way to
map it directly into the system as I remember a 4GB limit of 32-bit
machines. Perhaps you could issue command to it instead and have the board
use a 64-bit system? In any case, you could use some type of hacked (because
of the 64-bitness of it) MD (malloc disk) to make a super fast file system.

All in all, I think something similar to this was approached using the IDE
interface, but IMHO, such a thing is much too slow for memory bandwidth.
(newer versions of PCI might be fast enough to get reasonable speed...)

James Alton
jalton at olsh.cx
TechOutside.com

-----Original Message-----
From: beowulf-admin at beowulf.org [mailto:beowulf-admin at beowulf.org]On
Behalf Of Amber Palekar
Sent: Thursday, August 16, 2001 2:35 AM
To: beowulf at beowulf.org
Subject: Network RAM for Beowulf


hi,
   we as a group of four students are *also* thinking
of implementing Network RAM for a beowulf cluster
(assuming 100Mbps Ethernet ) whereby each node in the
cluster will donate some part of their RAM to be used
by all other nodes.so we will basically be mapping
this shared RAM to the address space of the current
node.One of the uses that we're thinking of is for
Journaling(as in file systems ).We'll be maintaining
the journals on the Network RAM instead of writing
them to the local disks.As we are completely new to
this , it is very difficult for us to determine the
statistics like :- the overhead in writing to Network
RAM . Any info or pointers to these stats would be
highly appreciated .
   TIA
    Amber

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