/proc/sys/dev/raid
The /proc/sys directory provides interfaces for manipulating tunable kernel parameters. These parameters, which affect various aspects of the kernel, can be fine-tuned while the system is running. For more general information about /proc/sys, consult the file in the /usr/src/linux/Documentation/sysctl directory of your kernel source code, as well as /usr/src/linux/Documenation/filesystems/proc.txt.
Two files in the /proc/sys/dev/raid
subdirectory provide a way to tune the speed at which array
resynchronization (and reconstruction) takes place.
speed_limit_min
and
speed_limit_max
define the minimum and maximum
speeds at which resynchronization occur. The latter is especially
useful on slower, or heavily utilized, systems, where you might find
that the resynchronization process slows down the system too much. In
that case, you could change the maximum speed—in effect, throttling
the resynchronization process to a more suitable level. The
md driver does provide its own I/O throttling and
will attempt to perform recovery nonintrusively, but using
speed_limit_min
and
speed_limit_max
can provide a quick fix if
something goes haywire.
You’ll need to experiment with your system to see the maximum speed it can handle. Adjusting the minimum speed affects the low-end limit for resynchronization. It might be a good idea to simulate a drive failure and play with these values so that you aren’t surprised when a real disk failure happens.
Tip
You can simulate a disk failure by using ...
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