From: Martin Wilck <mwilck@xxxxxxxx> The statement that the default is 600 is wrong in most cases. Improve the description of the default and the dependency of this parameter on other parameters. Cc: Martin Wilck <mwilck@xxxxxxxx> Cc: Benjamin Marzinski <bmarzins@xxxxxxxxxx> Cc: Christophe Varoqui <christophe.varoqui@xxxxxxxxxxx> Cc: DM-DEVEL ML <dm-devel@xxxxxxxxxx> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx> Reviewed-by: Xose Vazquez Perez <xose.vazquez@xxxxxxxxx> --- v2: unchanged text, just move "default value" to bottom --- multipath/multipath.conf.5 | 39 ++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5 index bd7d7788..76a6fb35 100644 --- a/multipath/multipath.conf.5 +++ b/multipath/multipath.conf.5 @@ -707,18 +707,33 @@ The default is: \fB5\fR . .TP .B dev_loss_tmo -Specify the number of seconds the SCSI layer will wait after a problem has -been detected on a FC remote port before removing it from the system. This -can be set to "infinity" which sets it to the max value of 2147483647 -seconds, or 68 years. It will be automatically adjusted to the overall -retry interval \fIno_path_retry\fR * \fIpolling_interval\fR -if a number of retries is given with \fIno_path_retry\fR and the -overall retry interval is longer than the specified \fIdev_loss_tmo\fR value. -The Linux kernel will cap this value to \fI600\fR if \fIfast_io_fail_tmo\fR -is not set. See KNOWN ISSUES. -.RS -.TP -The default is: \fB600\fR +Specify the number of seconds the SCSI layer will wait after a connection loss has +been detected on a remote port before removing it from the system. This +can be set to "infinity", which effectively means 136 years (2^32-1 seconds). +This parameter is only applied to Fibre Channel and SAS devices. +.RS +.LP +The value of \fIdev_loss_tmo\fR is restricted by other settings. +If \fIfast_io_fail_tmo\fR is set to a positive value, \fBmultipathd\fR +will make sure that the value of \fIdev_loss_tmo\fR is larger than +\fIno_path_retry\fR * \fIpolling_interval\fR. +If \fIfast_io_fail_tmo\fR is not set, the kernel limits the \fIdev_loss_tmo\fR +value to 600 seconds. +In this case, the user has to make sure that \fIno_path_retry\fR is smaller +than \fIdev_loss_tmo / polling_interval\fR. In particular, +\fIno_path_retry\fR must not be set to \(dq\fIqueue\fR\(dq. See KNOWN ISSUES. +.LP +When path devices reappear after a connection loss, it is much easier for +the kernel to simply reactivate an inactive device than to re-add +a previously deleted one. It is therefore recommended to set +\fIdev_loss_tmo\fR to a large value within the restrictions mentioned above. +.LP +Fibre Channel and SAS devices have hardware-dependent defaults, which are left +unchanged if \fIdev_loss_tmo\fR is not specified. For a few storage arrays, +the multipath-tools built-in settings override the default. Run \fImultipath -T\fR +to see the settings for your device. +.TP +The default is: \fB<hardware dependent>\fR .RE . . -- 2.38.1 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
