File ownership & permission on compute nodes (Scyld)
becker at scyld.com
Thu Jan 17 11:21:29 PST 2002
On Thu, 17 Jan 2002, Tony Stocker wrote:
> I'm using the 'freebie' version of Scyld [27bz-8]. We are running several
> tests on our cluster comparing performance of our algorithms versus some
> heavy metal platforms. When running very I/O intensive algorithms over NFS
> we see major performance hits, obviously.
> I can create the directories (as root) just fine. But for some reason I can
> not get the file/directory ownership to read the passwd file. It appears to
> read the group file fine. What I did was copy over /etc/passwd and
> /etc/group to the compute nodes' /etc directory.
Verify that your /etc/nsswitch.conf configuration file has both "bproc"
and "files" entries. This file is created by /etc/beowulf/node_up
(really /usr/lib/beoboot/bin/node_up) each time a slave node is started.
> It's as if it's not bothering to look at the passwd file at all.
Correct. For most cluster configurations there is no /etc/passwd file.
User name (really password entry -- 'pwent') information is provided by
the BeoNSS name service. When user starts a process on a cluster slave node,
the only valid getpwent() entry for that process is that single user.
If you do add "files" to the name service switch creation in the node_up
script you might also want to 'scp -p /etc/passwd $NODE:/etc' in the
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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