.Dd November 30, 2017

.Dd June 11, 2019

First of all, a kernel dump will go only to one component and

First of all, when

.Xr dumpon 8

is called

.Nm

always chooses the provider with the highest priority.  That provider

will be the only

.Nm

member with the kernel dump present.

Retrieving the dump on next boot is therefore conditional on two factors:

.Bl    -bullet    -offset    indent -compact

.It

The

always chooses the component with the highest priority.

balance algorithm must be

Reading a dump from the mirror on boot will only work if the

balance algorithm is used (that way

.It

The

will read only from the component with the highest priority).

provider with the highest priority must remain consistent between when

If you use a different balance algorithm, you should add:

.Xr dumpon 8

and

.Xr savecore 8

are called (on panic, and upon next boot, respectively).

.El

If either of the above points are not ensured, when

.Xr savecore 8

is called

.Nm

is liable to return from the provider without the kernel dump present,

and

.Xr savecore 8 will not be able to process the dump.

Placing the below script in

.Pa /usr/local/etc/rc.d

will ensure that the

.Nm

balance algorithm is set to 

.Cm prefer

and that a provider has a set priority when

.Xr savecore 8

is called.

gmirror configure -b prefer data

#!/bin/sh

# PROVIDE: gmirror_prefer_algo

# REQUIRE: disks

# BEFORE: savecore gmirror_balance_algo

# KEYWORD: nojail

\&. etc/rc.subr

name=gmirror_prefer_algo

desc="Sets gmirror balance algorithm to prefer and sets a provider priority"

rcvar=gmirror_prefer_algo_enable

start_cmd="${name}_start"

stop_cmd=":"

load_rc_config $name

: ${gmirror_prefer_algo_enable="NO"}

: ${gmirror_prefer_algo_mirror=""}

: ${gmirror_prefer_algo_provider=""}

: ${gmirror_prefer_algo_priority=1}

gmirror_prefer_start()

{

    balance_cmd="gmirror configure -b prefer ${gmirror_prefer_algo_mirror}"

    priority_cmd="gmirror configure -p ${gmirror_prefer_algo_priority} ${gmirror_prefer_algo_mirror} ${gmirror_prefer_algo_provider}"

    $balance_cmd

    $priority_cmd

}

run_rc_command "$1"

.Pp

to the

Add the below lines to /usr/local/etc/rc.conf to enable the script and specify

.Pa /etc/rc.early

.Nm

script and:

configuration:

gmirror configure -b round-robin data

gmirror_prefer_algo_enable="YES"

gmirror_prefer_algo_mirror="yourmirrorname" # Specify the name of the gmirror to configure.

gmirror_prefer_algo_provider="yourprovidername" # Specify the name of the provider to configure.

gmirror_prefer_algo_priority=N # Specify the priority of the provider to configure, where N is a valid priority integer.

.Pp

to the

.Sy Note:

.Pa /etc/rc.local

It is adviseable to create your gmirror with "-h" and add  providers via GPT or GEOM labels so as to ensure the provider name will be consistent.

script.

The decision which component to choose for dumping is made when

If a

.Xr dumpon 8

algorithm other than 

is called.

.Cm prefer

If on the next boot a component with a higher priority will be available,

is desired for normal

the prefer algorithm will choose to read from it and

.Nm

operation, placing the below script in

.Pa /usr/local/etc/rc.d

will ensure that the

.Nm

balance algorithm is re-configured after

will find nothing.

is called.

If on the next boot a component with the highest priority will be synchronized,

the prefer balance algorithm will read from the next one, thus will find nothing

.Bd -literal -offset indent

there.

#!/bin/sh

# PROVIDE: gmirror_balance_algo

# REQUIRE: savecore gmirror_prefer_algo

# BEFORE:

# KEYWORD: nojail

\&. etc/rc.subr

name=gmirror_balance_algo

desc="Sets gmirror balance algorithm"

rcvar=gmirror_prefer_algo_enable

start_cmd="${name}_start"

stop_cmd=":"

load_rc_config $name

: ${gmirror_prefer_algo_enable="NO"}

: ${gmirror_prefer_algo_mirror=""}

: ${gmirror_balance_algo="load"}

gmirror_balance_algo_start()

{

    balance_cmd="gmirror configure -b ${gmirror_balance_algo} ${gmirror_prefer_mirror}"

    $balance_cmd

}

run_rc_command "$1"

.Ed

Add the below lines to /usr/local/etc/rc.conf to enable the script and specify

.Nm

configuration:

.Bd -literal -offset indent

gmirror_balance_algo="algo" # Specify the balance algorithm to be used for normal gmirror operation, where "algo" is a valid

balance algorithm.

.Ed