Check settings on Redis

[davies]

What would you like to be added:

After connected to Redis, check the following settings on redis:

1. AOF is ON
2. RDB is ON
3. no in cluster mode (cluster_enabled is 0)
4. maxmemory_policy is set to noeviction
5. show a warning if it's not replicated
6. version should be >= 2.2

Why is this needed:

Redis is responsible for persistence of metadata, so it should NOT lose any data, otherwise the data in JuiceFS will be lost.

[suzaku]

How do we check if RDB is disabled? The only related configuration seems to be the "save" interval.

[vision9527]

What is the best redis's deployment strategy? Is there some more detail about it?

[davies]

How do we check if RDB is disabled? The only related configuration seems to be the "save" interval.

Yeah, may be just ignore it (assume RDB is always enabled).

[davies]

What is the best redis's deployment strategy? Is there some more detail about it?

There should be many articles on this topic, for example, https://redis.io/topics/persistence

We can build a best practice for JuiceFS.

[suzaku]

How do we check if RDB is disabled? The only related configuration seems to be the "save" interval.

Yeah, may be just ignore it (assume RDB is always enabled).

Seems straight forward enough, could you assign this issue to me? I'll work on it when I have some time to spare.