[LUDOC-247] recovery_time_soft and recovery_time_hard default value descriptions are misleading

Tue, 16 Feb 2016 16:18:29 +0000

The documentation for the OST mount options recovery_time_soft and recovery_time_hard is misleading in the way that it describes the default values for these parameters.

For recovery_time_soft, it says: "The default soft recovery timeout is 300 seconds (5 minutes)."

For recovery_time_hard, it says: "The default hard recovery timeout is set to 900 seconds (15 minutes)."

The default (if the recovery_time_{soft,hard} mount options are not given) is actually dependent upon the value of the RPC timeout value which is described in section 32.5.2 of the Lustre manual as "The time that a client waits for a server to complete an RPC....".

The recovery_time_{soft,hard} values are set at mount time in the function server_calc_timeout(). If no recovery_time_{soft,hard} options are given to the mount command, the values are set as follows:

        if (soft == 0)
                soft = OBD_RECOVERY_TIME_SOFT;
        if (hard == 0)
                hard = OBD_RECOVERY_TIME_HARD;

Those macros are defined as follows:

#define OBD_RECOVERY_TIME_HARD          (obd_timeout * 9)
#define OBD_RECOVERY_TIME_SOFT          (obd_timeout * 3)

Thus, the default values of recovery_time_soft and recovery_time_hard are actually 3 times the RPC timeout and 9 times the RPC timeout, respectively. If the RPC timeout is set to the default 100 seconds (at OST mount time), then the default values of recovery_time_soft and recovery_time_hard are 300 and 900 seconds, respectively.

Whamcloud Community JIRA

[LUDOC-247] recovery_time_soft and recovery_time_hard default value descriptions are misleading