Lustre 1.6 Operations Manual

The sgpdd_survey script must be customized according to the particular device
being tested and also according to the location where it should keep its working
files. Customization variables are described explicitly at the start of the script.
When the sgpdd_survey script runs, it creates a number of working files and a pair
of result files. All files start with the prefix given by the script variable ${rslt}.
${rslt}_.summary same as stdout
${rslt}__* tmp files
${rslt}_.detail collected tmp files for post-mortem
The summary file and stdout should contain lines like this:
total_size 8388608K rsz 1024 thr 1 crg 1 180.45 MB/s 1 x 180.50 \
=/ 180.50 MB/s
The number immediately before the first MB/s is bandwidth, computed by
measuring total data and elapsed time. The remaining numbers are a check on the
bandwidths reported by the individual sgp_dd instances.
If there are so many threads that the sgp_dd script is unlikely to be able to allocate
I/O buffers, then "ENOMEM" is printed.
If one or more sgp_dd instances do not successfully report a bandwidth number,
then "failed" is printed.
19.2.2 obdfilter_survey
The obdfilter_survey script processes sequential I/O with varying numbers of
threads and objects (files) by using lctl::test_brw to drive the echo_client
connected to local or remote obdfilter instances, or remote obdecho instances. It can
be used to characterize the performance of the following Lustre components:
Stripe F/S
Here, the script directly exercises one or more instances of obdfilter. The script may
be running on one or more nodes, for example, when the nodes are all attached to
the same multi-ported disk subsystem.
You need to tell the script the names of all obdfilter instances, which should already
be up and running. If some instances are on different nodes, then you also need to
specify their hostnames, for example, node1:ost1. All the obdfilter instances are
driven directly. The script automatically loads the obdecho module (if required) and
creates one instance of echo_client for each obdfilter instance.
19-4 Lustre 1.6 Operations Manual • September 2008