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Lustre 1.6 Operations Manual

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23.2.5 Printing to /var/log/messages<br />

To dump debug messages to the console, set the corresponding debug mask in the<br />

printk flag:<br />

sysctl -w lnet.printk=-1<br />

This slows down the system dramatically. It is also possible to selectively enable or<br />

disable this for particular flags using:<br />

sysctl -w lnet.printk=+vfstrace<br />

sysctl -w lnet.printk=-vfstrace<br />

23.2.6 Tracing Lock Traffic<br />

<strong>Lustre</strong> has a specific debug type category for tracing lock traffic. Use:<br />

lctl> filter all_types<br />

lctl> show dlmtrace<br />

lctl> debug_kernel [filename]<br />

23.2.7 Sample lctl Run<br />

bash-2.04# ./lctl<br />

lctl > debug_kernel /tmp/lustre_logs/log_all<br />

Debug log: 324 lines, 324 kept, 0 dropped.<br />

lctl > filter trace<br />

Disabling output of type "trace"<br />

lctl > debug_kernel /tmp/lustre_logs/log_notrace<br />

Debug log: 324 lines, 282 kept, 42 dropped.<br />

lctl > show trace<br />

Enabling output of type "trace"<br />

lctl > filter portals<br />

Disabling output from subsystem "portals"<br />

lctl > debug_kernel /tmp/lustre_logs/log_noportals<br />

Debug log: 324 lines, 258 kept, 66 dropped.<br />

Chapter 23 <strong>Lustre</strong> Debugging 23-9

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