If it is client level configuration, in theory it is possible to have latest client create v3 ledger while bookies are still running in the older version right? Who can stop that? if we let that happen what happens to the replication logic? How can it handle the new ledger format?
If we go with cluster level, I think using it part of LAYOUT_ZNODE is not clean. I think we need to have a form of "cluster version number", or even better with a combination of capability/feature bit-map which can dictate the cluster behavior. I am assuming that the tool Ivan is talking about is used for existing clusters to update the cluster version number. Otherwise the maxLedgerMetadataFormat is used only for new clusters; that is fine. But this comes with strict operational guidelines where the maxLedgerMetadataFormat needs to be updated after successful upgrade of the entire cluster to new bits. In this case at least we have a barrier that the entire bookies are updated which can understand maxLedgerMetadataFormat, and we support backward compatibility anyway. But I don't like the way to overload LAYOUT_ZNODE which doesn't make sense as it is not a layout change. JV On Tue, Dec 18, 2018 at 11:37 AM Sam Just <sj...@salesforce.com> wrote: > I think both approaches are viable, but I think that the max allowable > version is more naturally a bk cluster property rather than a bk client > property. Controlling this from the client means that the same client > version deployed to two different clusters might need different settings > depending on the other clients deployed to those clusters. Placing it in > the metadata means that the clients simply pick up the correct version for > the environment from the ledger metadata without needing additional > configuration. However, client config management is likely to be managed > on a per-cluster basis anyway, so in practice there may be little > difference. > -Sam > > On Tue, Dec 18, 2018 at 10:01 AM Sam Just <sj...@salesforce.com> wrote: > > > I'll take a look. > > > > On Tue, Dec 18, 2018 at 1:39 AM Ivan Kelly <iv...@apache.org> wrote: > > > >> JV, Sam, Charan, Andrey, could one of you chime in on this? It's > >> holding up 4.9 release. > >> > >> -Ivan > >> > >> On Thu, Dec 13, 2018 at 5:38 PM Ivan Kelly <iv...@apache.org> wrote: > >> > > >> > I'd be interested to see the opinion of the salesforce folks on this. > >> > On Thu, Dec 13, 2018 at 5:35 PM Ivan Kelly <iv...@apache.org> wrote: > >> > > > >> > > > I am not sure about this. If clients don't react the changes of > >> ledger > >> > > > layout, > >> > > > the information in ledger layout is just informative, you still > >> need to > >> > > > coordinate > >> > > > both readers and writers. so IMO the version in ledger layout is > >> not really > >> > > > useful. > >> > > > >> > > The clients react the next time they initialize the ledger manager. > >> > > Which is exactly the same as would occur with a configuration > setting. > >> > > > >> > > -Ivan > >> > > > > > > -- > > > > <http://smart.salesforce.com/sig/sjust//us_mb/default/link.html> > > > > > -- > > <http://smart.salesforce.com/sig/sjust//us_mb/default/link.html> > -- Jvrao --- First they ignore you, then they laugh at you, then they fight you, then you win. - Mahatma Gandhi
