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5 – Detailed Descriptions of Command LineTools
Basic Setup and Administration Tools
5-14 D000006-000 Rev A
Q
Fast Fabric provides additional flexibility in the translation between IPoIB and
management network hostnames. Refer to
appendix C for more information.
Setup_ssh
provides an easy way to create ssh keys and distribute them to the
hosts in the cluster. Many of the Fast Fabric tools (as well as many versions of
MPI) require ssh be set up for password-less operation. Therefore,
setup_ssh
is an important setup step.
This tool also sets up ssh to the local host and the local hosts IPoIB name. This
capability is required by selected Fast Fabric commands and may be used by
some applications (such as MPI).
Setup_ssh
has two modes of operation. The mode is selected by the presence
or absence of the
-C
option. Typically,
setup_ssh
will first be run without the
-C
option, then it may later be run with the
-C
option.
Initial key exchange
When run without the
-C
option,
setup_ssh
will perform the initial key exchange
and enable password-less ssh and scp. The key exchange can be accomplished
using ssh and scp (in a password prompting manner) via the
-s
option or using
password-less rsh and rcp (omitting the
-s
option).
The preferred way to use
setup_ssh
for initial key exchange is with the
-s
and
-S
options. This requires all hosts have been configured with the same
password for the specified "user" (typically
root
). In this mode the password
will be prompted for once and then ssh and scp are used in conjunction with that
password to complete the setup for the hosts. Use in this manner also avoids
the need to setup rsh/rcp/rlogin (which can be a security risk).
If
-s
is used without the
-S
option, the user will be prompted by ssh and scp for
each host as they are setup. There will be multiple prompts per host. For a
handful of hosts this is manageable, however for a significant number of hosts
this can become cumbersome. Therefore, the
-S
option is recommended in this
case.
If the
-s
option is not specified, rsh and rcp will be used to perform the ssh key
exchange. This requires password-less rcp and rlogin be enabled on each host
(
check_rsh
can perform verification).
Setup_ssh
will configure password-less ssh/scp for both the management
network and IPoIB. Typically, the management network will be used for Fast
Fabric while IPoIB will be used for MPI and other applications. If IPoIB is not yet
running (for example, during initial cluster installation IB software will not yet be
installed on all the hosts), the
-i
option can be specified with an empty string:
setup_ssh -i ''
This will cause the last part of the setup of ssh for IPoIB to be skipped.
Refreshing local systems known hosts