- Elasticsearch – What to Do Before You Go to Production
The list, in the order it bites. Shard sizing and why more shards is usually the wrong instinct, replicas and what green actually promises, JVM heap and the 50% rule, security beyond turning it on — an API key scoped to one index rather than the elastic superuser every guide leaves you using — index lifecycle management, what to monitor, and the failure modes to rehearse before they happen.
- Elasticsearch – Snapshots, Restores and SLM
Registering a repository, taking a snapshot, restoring it, and automating the whole thing with a lifecycle policy — plus the retention setting that stops a cluster which was off for a month from deleting every backup it has the moment it comes back. And an honest answer to the question underneath: if your index is derived from a database, a rebuild may be the better restore, and knowing which is the point.
- Elasticsearch – The _cat APIs and Reading Cluster Health
The APIs you actually type when something is wrong. _cat/health, indices, nodes, shards and allocation, with the v, h and s parameters that make them readable. Then the questions they answer: what yellow really means and why a single-node cluster is yellow by default, which shard is unassigned and why, where the disk went, and how to tell a slow query from a slow cluster.
- Linux Screen
Imagine having to execute a long running process and waiting for it to finish, most likely you are connected via ssh and you can’t do anything else but waiting for that process to finish. When the process is taking too long your connection will time out and you will be kicked out. When that happens…
- Elasticsearch – Aliases and Zero-Downtime Reindexing
A field type cannot be changed once it has been written, so sooner or later you have to move every document into a new index. Whether that is an outage depends on one decision you make on day one: never let your application name a concrete index. Aliases, _reindex, the atomic alias swap, what happens to writes that land during the copy, and how to migrate a cluster that already got this wrong.