User Manual

Rev 2.3-1.0.1
Mellanox Technologies
73
3.2.2 OpenSM
OpenSM is an InfiniBand compliant Subnet Manager (SM). It is provided as a fixed flow execut-
able called “opensm”, accompanied by a testing application called “osmtest”. OpenSM imple-
ments an InfiniBand compliant SM according to the InfiniBand Architecture Specification
chapters: Management Model (13), Subnet Management (14), and Subnet
Administration (15).
3.2.2.1 opensm
opensm is an InfiniBand compliant Subnet Manager and Subnet Administrator that runs on top of
the Mellanox OFED stack.
opensm performs the InfiniBand specification’s required tasks for ini-
tializing InfiniBand hardware. One SM must be running for each InfiniBand subnet.
opensm also provides an experimental version of a performance manager.
opensm defaults were designed to meet the common case usage on clusters with up to a few hun-
dred nodes. Thus, in this default mode,
opensm will scan the IB fabric, initialize it, and sweep
occasionally for changes.
opensm attaches to a specific IB port on the local machine and configures only the fabric con-
nected to it. (If the local machine has other IB ports,
opensm will ignore the fabrics connected to
those other ports). If no port is specified,
opensm will select the first “best” available port.
opensm can also present the available ports and prompt for a port number to attach to.
By default, the
opensm run is logged to two files: /var/log/messages and /var/log/
opensm.log. The first file will register only general major events, whereas the second file will
include details of reported errors. All errors reported in this second file should be treated as indi-
cators of IB fabric health issues. (Note that when a fatal and non-recoverable error occurs,
opensm will exit). Both log files should include the message "SUBNET UP" if opensm was able
to setup the subnet correctly
.
Syntax
opensm [OPTIONS]
For the complete list of opensm options, please run:
opensm --help / -h / -?
3.2.2.1.1 Environment Variables
The following environment variables control opensm behavior:
• OSM_TMP_DIR
Controls the directory in which the temporary files generated by opensm are created. These
files are:
opensm-subnet.lst, opensm.fdbs, and opensm.mcfdbs. By default, this direc-
tory is
/var/log.
• OSM_CACHE_DIR
opensm stores certain data to the disk such that subsequent runs are consistent. The default
directory used is
/var/cache/opensm. The following file is included in it:
•
guid2lid – stores the LID range assigned to each GUID
3.2.2.1.2 Signaling
When OpenSM receives a HUP signal, it starts a new heavy sweep as if a trap has been received
or a topology change has been found.