Disk I/O Requests Cause Low Throughput And High Latency On Linux34; Disk I/O Requests Cause Low Throughput And High Latency On Vmware - Brocade Communications Systems CNA 1010 Troubleshooting Manual

3. Possible Cause: Zoning is configured incorrectly on FCoE switch.
I/Os are not failing over immediately on path failure in MPIO setup
When multipath I/O (MPIO) is enabled and input/output operations are not failing over immediately
when a path failure occurs, refer to the following descriptions of possible causes and
recommended actions to help resolve the problem.
Possible Cause: Improper driver mpiomode setting.
Action: Execute the port --query <port_id> BCU command and ensure fcpim MPIO mode is enabled
(which implies zero Path TOV values) or that fcpim MPIO mode is disabled with the expected "Path
TOV" settings (default is 30 seconds).
Disk I/O requests cause low throughput and high latency on Linux
If a high number of I/O requests is causing low throughput and high latency on Linux systems, refer
to the following descriptions of possible causes and recommended actions to help resolve the
problem.
Possible Cause: The maximum input/output operations per second are too low on Linux hosts.
Action: Refer to
Linux systems.

Disk I/O requests cause low throughput and high latency on VMware

If a high number of I/O requests is causing low throughput and high latency on VMware systems,
refer to the following descriptions of possible causes and recommended actions to help resolve the
problem.
Possible Cause: The maximum input/output operations per second are too low on VMware hosts.
Action: Refer to
VMware systems.
Brocade Adapters Troubleshooting Guide
53-1001582-01
Action: Configure PFC using the appropriate Fabric OS command on the attached switch while
in switch configuration mode.
Action: Verify zoning configuration on the attached switch using the appropriate Fabric OS
command. Refer to the Fabric OS Command Reference Manual for more information.
"Linux tuning"
"VMware tuning"
FCoE and Fibre Channel problems
on page 93 for suggestions to optimize adapter performance in
on page 95 for suggestions to optimize adapter performance in
2
33