Starting here: https://docs.nextcloud.com/server/latest/admin_manual/maintenance/migrating.html?highl
Basically we'll setup the new server according to the install guide, and turn on maintenance mode of the old server in order to dump the db and filesystem and transfer them to the new server.
As of the time of writing this, Nextcloud stable is at version 19, and the new server being setup is a fresh Debian 10 (buster) install.
Needed:
Recommended:
php-common on Debian 10 pulls in many of these like php-ctype, php-xml, php-mbstring, php-fileinfo, php-exif, php-pcntl , etc. We'll also need to choose a DB module; in this case we'll be using MariaDB so the mysql driver is needed.
This is what I ended up needing to install:
```sudo apt install -y php-curl \ php-gd \ php-json \ php-bz2 \ php-imagick \ php-bcmath \ ffmpeg \
#### Memory Cache
The old server is using `redis` so we'll stay with that.
```sudo apt install redis-server php-redis```
Installing and configuring `redis` is outside of the scope of this post; but [this Digital Ocean guide](https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-debian-10) is easy to run through. TLDR: make sure to set a password with the `requirepass` config directive, ensure remote access is turned off (if you're running it on the same server as the Nextcloud instance, and make `systemd` watch the process.
> WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
echo 'vm.overcommit_memory = 1' >> /etc/sysctl.conf sysctl vm.overcommit_memory=1
> WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
```echo "never" > /sys/kernel/mm/transparent_hugepage/enabled```
> WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
The Nextcloud install guide recommends `redis` for everyhing but local cache:
'memcache.local' => '\OC\Memcache\APCu', 'memcache.distributed' => '\OC\Memcache\Redis', 'memcache.locking' => '\OC\Memcache\Redis',
but I was getting an error message in `nextcloud.log` about `APCu` not working:
```nextcloud Memcache \\OC\\Memcache\\APCu not available for local cache```
so ended up just sticking with `redis` for everything.
The redis setup with systemd on a fresh Debian 10 server was a mess and took some fiddling. Here are the relevant portions of configs having to do with redis, nextcloud config, and systemd service file:
##### Nextcloud `config.php`:
'memcache.local' => '\OC\Memcache\Redis', 'memcache.distributed' => '\OC\Memcache\Redis', 'memcache.locking' => '\OC\Memcache\Redis', 'redis' => [ 'host' => '/var/run/redis/redis-server.sock', 'dbindex' => 0, 'password' => 'kG34qzSTk6M3Wm1Dg6ZRw58oZMOBnxD6FrHi6qvV0aAgT1P2J3qB', 'timeout' => 1.5, ],
##### Redis conf file `/etc/redis/redis.conf`:
bind 127.0.0.1 port 0 unixsocket /var/run/redis/redis-server.sock unixsocketperm 770 daemonize yes supervised systemd pidfile /var/run/redis/redis-server.pid
##### Systemd redis Config File
[Service]
Type=notify ExecStart=/usr/bin/redis-server /etc/redis/redis.conf ExecStop=/bin/kill -s TERM $MAINPID ExecStartPost=/bin/sleep 1
PIDFile=/var/run/redis/redis-server.pid TimeoutStopSec=0 Restart=always User=redis Group=redis RuntimeDirectory=redis RuntimeDirectoryMode=2775 ```
Hopefully we can just copy the config from the old server, but there are specific instructions in the install guide: https://docs.nextcloud.com/server/stable/admin_manual/installation/source_installation.html#apache-web-server-configuration
Need:
Recommended:
sudo a2enmod rewrite headers env dir mime ssl
Now that the new server is ready and setup to run Nextcloud, return to the old server and turn on maintenance mode:
In the web root of the old Nextcloud install run:
sudo -u www-data php occ maintenance:mode --on
Not sure if required, but after 10 minutes I also used a2dissite to temporarily disable the entire Nextcloud site while taking the DB and filesystem backups in the next step.