Recovering from a failed ibv_devinfo command

The ibv_devinfo command can fail when modules or hardware drivers fail to load or when libraries are missing.

About this task

The ibv_devinfo command generally fails with one of two common errors. The recovery steps for each of those two errors, and one less common error, are given below.

Procedure

Error: Failed to get IB devices list: Function not implemented.
One of the common causes of this failure is that the ib_uverbs module might not by loaded or it might not be enabled at the correct run levels. To recover from this error, complete the following steps:
1. To verify the ib_uverbs module is loaded, run the following command and look for similar output:
```
lsmod | grep ib_uverbs

ib_uverbs              44238  0
```
2. To verify that the RDMA run level is set to on for levels 3 and 5, run the following command and look for similar output:
```
chkconfig --list | grep rdma

0:off 1:off 2:off 3:on 4:off 5:on 6:off 
```
  If RDMA is off, run the following commands to activate RDMA on levels 3 and 5:
```
chkconfig --level 3 rdma on 
	chkconfig --level 5 rdma on
```
  Run the following command to restart RDMA:
```
openibd restart/rdma restart
```
3. If there is a missing library, you will see an error similar to the following:
```
libibverbs: Warning: couldn't load driver 'mlx4': libmlx4-rdmav2.so: cannot open shared object file: No such file or directory 
	libibverbs: Warning: no userspace device-specific driver found for /sys/class/infiniband_verbs/uverbs0 
	No IB devices found. 
```
  If you receive this error, install the libmlx4 user level library.
Error: No IB devices found.
If no IB devices are found, complete the following steps:
1. Check to see if the relevant hardware driver is loaded. If a hardware driver is missing, then run the following command:
```
modprobe <hardware driver>
```
2. Verify that the hardware driver is loaded by default by editing the configuration file.
3. Run the following command to restart RDMA:
```
openibd restart/rdma restart
```
Error: On Red Hat Enterprise Linux 5.x on ppc64, the wrong libraries are installed.
Red Hat Enterprise Linux 5.x on ppc64 requires 32-bit user level libraries like libmlx4. However, by default, the 64-bit libraries are installed. Make sure that you have the correct 32-bit libraries installed.