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by Spivak 1223 days ago
That's not what the parent means by durability, they mean having your data survive any one of your machines being instantly nuked from orbit at the most inconvenient possible time.

Just having sync replication is enough, doesn't have to be fancy like semi-sync.

2 comments

i know that

i'm correcting their terminology

'durability' already has a well-established, rigorously-defined meaning in this context, which is confusingly similar to pitr but definitely not the same thing

the downside of sync replication, as i understand it, is that although your data will survive any one of your machines being instantly nuked from orbit, your entire service will go down; semi-sync avoids this problem

But they’re using the other well-established meaning of durability a la how AWS and others describe their storage platforms. It’s pretty much the same thing but taken at whole system level. On that level an ACID database is as durable as the underlying storage medium which is sadly not very durable.
well, it's sort of arbitrary that the standard definition of durability requires your data to survive machine checks and kernel panics and power outages but not disk failures, isn't it

especially since nowadays in many data centers disk failures are far more common

(though full raid failures are less common)

but that is the standard definition

Michael, is that you?