* Rolling restart instructions
In a rolling restart scenario, indexing do not need to be stopped. This step is optional. I have updated Rolling restart/ step 2.
Note: I am not sure how to check if the doc, once generated, will keep the numbering as section 1 and 3 are references to the full restart, can you check this detail?
* Clarify that shard recovery can be faster
Co-authored-by: Adam Locke <adam.locke@elastic.co>
When doing a rolling restart we recommend disabling shard allocation to
avoid unnecessary recoveries. However, this advise is unnecessary or
even harmful when restarting nodes that do not carry any data like a
pure ML node.
Synced flush was a brilliant idea. It supports instant recoveries with a
quite small implementation. However, with the presence of sequence
numbers and retention leases, it is no longer needed. This change
removes it from 8.0.
Relates #5077
