search

apple / foundationdb

FoundationDB - the open source, distributed, transactional key-value store
https://apple.github.io/foundationdb/
Apache License 2.0
14.43k stars 1.31k forks source link

Report error when a machine ends up having different zone id's #1123

Open bnamasivayam opened 5 years ago

bnamasivayam commented 5 years ago

Currently there is a possibility where processes in a machine can end up having different zoneId's. For example, running number of fdbservers on the same machine with different zoneId being set will lead to this scenario. This is not fatal but it can lead to some confusion as our status reports on machine assumes that all processes in the machine have same zoneId and datacenterId. There should be some form of error reporting to the user indicating the misconfiguration or may be there is a possibility of auto-correcting it.

alexmiller-apple commented 5 years ago

Does this mean we're formally declaring that zoneid needs to be a larger granularity than machineid ? I'm not aware that there was any restriction before on how one could arrange zoneids. I'm specifically thinking that zoneid == disk UID might be a thing a person could do.

bnamasivayam commented 5 years ago

If we could have a machine to be part of multiple zones, then we should change the logic of machine status returning locality info. Currently it assumes a machine to be in one zone only.

xumengpanda commented 5 years ago

zoneid is used as a larger granularity than machined in team collection, which affects where a shard is placed. To be specific, zoneid is viewed as a machine rack in team collection. If we change zoneid to anything with smaller granularity than machineid, say disk UID, we may hurt the purpose of team collection and increase the probability of data loss when a machine fails.