Product specifications

1–Overview of the Release
Other Information
1-14 D000069-024
Other Information
The following is a list of “need to know” information for this release:
 When using Mellanox Host Channel Adapters, any changes to Virtual
Fabrics (vFabrics) in the Fabric Manager, may require a reboot of the hosts
with Mellanox Host Channel Adapters. This limitation relates to the Mellanox
Host Channel Adapters not properly responding to changes to the Fabric
Manager service level (SL). For some vFabric configuration changes, if the
Fabric Manager SL changes or is mapped to a different Virtual Lane (VL)
than previously, the Mellanox Host Channel Adapter can continue to use the
previous VL. If that VL is presently disabled by the Fabric Manager, future
uses of applications which use the Fabric Manager SL may hang or timeout
because there are no VL Arbitration cycles for that VL. As a result, anytime
vFabric configuration is changed, it is recommended to reboot all hosts with
Mellanox Host Channel Adapters so that the desired Quality of Service
(QoS) configuration changes fully take effect. Any hosts with QLogic Host
Channel Adapters will not need to be rebooted.
Due to Mellanox Host Channel Adapters not correctly handling changes to
the Fabric Manager SL, QLogic recommends that all the hosts using
Mellanox ConnectX or ConnectX-2 Host Channel Adapters be rebooted
when used in a virtual fabric configuration.
 When Dispersive Routing is enabled, it allows packets sent using an MPI
program run over PSM to take any one of several routes through a fabric,
thus often increasing performance. The number of routes is determined by
the value of 2 to the power of the Lid Mask Control setting (LMC). Because
LMC defaults to 0, the default number of routes through the fabric is 2
0
or 1.
LMC can be set as high as 3, allowing a total number of 2
3
or 8 routes
through the fabric. Providing these additional routes can reduce fabric
congestion, and thus improve performance. Dispersive Routing is supported
when the Qlogic Fabric Manager is used in the fabric. Dispersive Routing is
not supported when using OpenSM.
 The current release of mvapich2 may have a memory management issue on
certain machines and certain MPI applications. If MPI applications hang
when using MVAPICH2, try using these settings with your application:
MV2_IBA_EAGER_THRESHOLD=16384 MV2_VBUF_TOTAL_SIZE=16384
When using QLogic's sample applications, these settings can be passed
using the ofed.mvapich2.params file (in /opt/iba/src/mpi_apps folder).
For other applications, they can be passed as part of the mpirun command.
 When running MVAPICH2, QLogic recommends turning off RDMA fast path.
To turn off RDMA fast path, specify MV2_USE_RDMA_FAST_PATH=0 in the
mpirun_rsh command line or set this option in the parameter file for
mvapich2.