Backing up or dumping a memcached server
I was needing to move from an old cache server to a larger one, but I wanted to do it without flushing cache.
The first thing I came across was this “memcached-tool” which has a dump command: https://github.com/memcached/memcached/blob/master/scripts/memcached-tool
There’s another article that mentions using memdump and memcat: How to dump memcached key/value pairs fast (archived)
Unfortunately, those methods only dumped a few mb of data. This post explains why: https://stackoverflow.com/a/13941700
You can only dump one page per slab class (1MB of data)
So, I ended up writing a script that loops through the expected cache keys, gets the data in cache, then sets the data in the new cache server.