Problem Booting the Slaves

Donald Becker becker at scyld.com
Fri Dec 15 10:41:40 EST 2000


> On Fri, 15 Dec 2000, David Leunen wrote:
> > monte: command line: panic=30 ramdisk_size=131072 apm=power-off
...
> > after that, there are all the register and stack status, and it is
> > frozen. The slaves are P200 16Ram Diskless. I tried with a double PII
> > 256Ram Diskless and it turn 'unavailable' after reboot. What is wrong
> > with the other ones?

On Fri, 15 Dec 2000, Dave Leimbach wrote:

> There is a parameter in that crash output about RAMDISK size.  If your
> machine only has 16MB I think you may be out of luck.  You need to get the
...
> The one that comes up unavailable has 256MB of RAM which is plenty of RAM
> for the ramdisks.  Scyld has an option in the beowulf distribution to run
> diskless.  I assume that this requires a large ramdisk that you can't get
> on the 16MB node.

That is correct.  We recommend 128MB for the compute nodes.
It's possible to run with only 64MB, but not less.

This minimum memory is the same for disk-based and diskless nodes.
The compute nodes always start as diskless nodes running from "ramdisk",
even if they get their initial boot kernel from the hard disk.

The nodes immediately start accepting commands from the master, before
mounting any filesystems.  Running in "diskless" mode allows the master to
control verification of file system integrity ("fsck"), create new file
systems, and recover checkpoint files without the risk of a node boot script
corrupting the system.

The bulk of the memory use is cached libraries.  'Bproc' automatically
transports missing/uncached libraries with the application executable, thus
not every library on the system must be cached.  But the libraries used by
the housekeeping processes ("slave daemons") on the compute node must always
exist locally.

Donald Becker				becker at scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993


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