Server Deployment Package (SDP) for Perforce Helix: SDP Failover Guide (for Unix and Windows)

Preface

The Server Deployment Package (SDP) is the implementation of Perforce’s recommendations for operating and managing a production Perforce Helix Core Version Control System. It is intended to provide the Helix Core administration team with tools to help:

High Availability (HA)
Disaster Recovery (DR)

This guide is intended to provide instructions for failover in an SDP environment using built in Helix Core features.

For more details see:

Sysadmin Guide - Failover

Please Give Us Feedback

Perforce welcomes feedback from our users. Please send any suggestions for improving this document or the SDP to consulting@perforce.com.

1. Overview

We need to consider planned vs unplanned failover. Planned may be due to upgrading the core Operating System or some other dependency in your infrastructure, or a similar activity.

Unplanned covers risks you are seeking to mitigate with failover:

loss of a machine, or some machine related hardware failure
loss of a VM cluster
failure of storage
loss of a data center or machine room
etc…

1.1. Planning

HA failover should not require a P4PORT change for end users. Depending on your topology, you can avoid changing P4PORT by having users set P4PORT to an alias, e.g. perforce.p4demo.com (or just perforce), or perforce_syd.p4demo.com (or just perforce_syd). During failover, that would be targeted by doing something like:

Changing a DNS alias so perforce.p4demo.com points to the backup machine.
Changing the Perforce broker configuration to target the backup machine.
Changing the Virtual IP configuration.
Changing the anycast routing configuration.

2. Planned Failover

In this instance you can run p4 failover with the active participation of its upstream server.

We are going to provide examples with the following assumptions:

serverid master_1 is current commit, running on machine bos-helix-01
serverid p4d_ha_bos is HA server
DNS alias perforce is set to bos-helix-01

2.1. Prerequisites

You need to ensure:

you are running p4d 2018.2 or later for your commit and all replica instances, preferably 2020.1
```
source /p4/common/bin/p4_vars 1
p4 info | grep version
```
your failover target server instance is of type standby or forwarding-standby

On HA machine:
```
p4 info
:
ServerID: p4d_ha_bos
Server services: standby
Replica of: perforce:1999
:
```

it has Options mandatory set in its server spec

p4 server -o p4d_ha_bos | grep Options
Options:  mandatory

you have a valid license installed in /p4/1/root (<instance> root)

On HA machine:
```
cat /p4/1/license
```
Monitoring is enabled - so the following works:
```
p4 monitor show -al
```
DNS changes are possible so that downstream replicas can seamlessly connect to HA server
Current pull status is valid
```
p4 pull -lj
```

2.2. Failing over

The basic actions are the same for Unix and Windows, but there are extra steps required as noted in Section 2.3, “Failing over on Windows”

Run p4 failover in reporting mode on HA machine:

p4 failover

Successful output looks like:

Checking if failover might be possible ...
Checking for archive file content not transferred ...
Verifying content of recently update archive files ...
After addressing any reported issues that might prevent failover, use --yes or -y to execute the failover.

Perform failover:

p4 failover --yes

Output should be something like:

Starting failover process ...
Refusing new commands on server from which failover is occurring ...
Giving commands already running time to complete ...
Stalling commands on server from which failover is occurring ...
Waiting for 'journalcopy' to complete its work ...
Waiting for 'pull -L' to complete its work ...
Waiting for 'pull -u' to complete its work ...
Checking for archive file content not transferred ...
Verifying content of recently updated archive files ...
Stopping server from which failover is occurring ...
Moving latest journalcopy'd journal into place as the active journal ...
Updating configuration of the failed-over server ...
Restarting this server ...

During this time, if you run commands against the master, you may see:

Server currently in failover mode, try again after failover has completed

Change the DNS entries so downstream replicas (and users) will connect to the new master (that was previously HA)
Validate that your downstream replicas are communicating with your new master

On each replica machine:
```
p4 pull -lj
```
Or against the new master:
```
p4 servers -J
```
Check output of p4 info:
```
:
Server address: box-helix-02
:
ServerID: master_1
Server services: commit-server
:
```
Make sure the old server spec (p4d_ha_bos) has correctly had its Options: field set to nomandatory (otherwise all replication would stop!)

2.3. Failing over on Windows

The basic steps are the same as for on Unix, but with some extra steps at the end.

After the p4 failover --yes command has completed its work (on the HA server machine):

Review the settings for the Windows service (examples are for instance 1) - note below -S is uppercase:

p4 set -S p4_1

Example results:

C:\p4\1>p4 set -S p4_1
:
P4JOURNAL=c:\p4\1\logs\journal (set -S)
P4LOG=c:\p4\1\logs\p4d_ha_aws.log (set -S)
P4NAME=p4d_ha_aws (set -S)
P4PORT=1666 (set -S)
P4ROOT=c:\p4\1\root (set -S)
:

Change the value of P4NAME and P4LOG to correct value for master:
```
p4 set -S p4_1 P4NAME=master
p4 set -S p4_1 P4LOG=c:\p4\1\logs\master.log
```
And re-check the output of p4 set -S p4_1

Restart the service:

c:\p4\common\bin\svcinst stop -n p4_1
c:\p4\common\bin\svcinst start -n p4_1

Run p4 configure show to check that the output is as expected for the above values.

3. Unplanned Failover

In this case there is no active participation of upstream server, so there is an increase risk of lost data.

We assume we are still failing over to the HA machine, so:

Failover target is standby or forwarding-standby
Server spec still has Options: set to mandatory
Original master is not running

The output of p4 failover on the DR machine might be:

Checking if failover might be possible ...
Server ID must be specified in the '-s' or --serverid' argument for a failover without the participation of the server from which failover is occurring.
Checking for archive file content not transferred ...
Verifying content of recently update archive files ...
After addressing any reported issues that might prevent failover, use --yes or -y to execute the failover.

Execute p4 failover with the extra parameter to specify server we are failing over from:
```
p4 failover --serverid master_1 --yes
```

Expected output is somewhat shorter than for planned failover:

Starting failover process ...
Waiting for 'pull -L' to complete its work ...
Checking for archive file content not transferred ...
Verifying content of recently updated archive files ...
Moving latest journalcopy'd journal into place as the active journal ...
Updating configuration of the failed-over server ...
Restarting this server ...

3.1. Unplanned Failover on Windows

The extra steps required are basically the same as in Section 2.3, “Failing over on Windows”

4. Old style failover

This does not use the p4 failover command (so is valid for pre-2018.2 p4d versions)

See: KB - Failing over to a Replica