Redis data persistency on Uberspace

Uberspace provides a nice german introduction on how to use Redis on their servers and also kindly points out that Redis resides in memory and will (when used with default settings) lose its state (speak: all your data *yikes*) when there is a crash or restart. So let us fix that:

Setting up Redis

Just a quick rehearsel of their tutorial. Redis is beeing set up in two steps basically:

test -d ~/service || uberspace-setup-svscan  
uberspace-setup-redis  

Enabling persistency

There are several persistency models you can read up on here: Redis persistence demystified. But I would recommend sticking with the most common way shown here, which strikes a good balance between performance and data safety[1].

nano ~/.redis/conf  

And then add the following lines:

dir /home/YOUR_UBERSPACE_USER_NAME/.redis/  
appendonly yes  
appendfsync everysec  
# Restart redis
svc -du ~/service/redis  

Verifying persistency

Now run the tool that will put data into Redis and make it do so. You can then check ① both that the persistency file grew to a size greater than 0 and ② also restart Redis and afterwards check whether your tool still sees the previously entered data.

# ① Check that the persistency file holds content:
du -sch ~/.redis/appendonly.aof  
# ② Restart Redis. This would kill all the contained data
# if the persistency setting would not work. Then check if
# the data is still available in your Redis using tool.
svc -du ~/service/redis  

Sources
1. Redis persistence demystified (oldblog.antirez.com)