Files are source files e.g. FileTxnLog.java that is related to Write Ahead Log and snapshot mechanism. And thanks for the explanation!
> -------- Original Message -------- > Subject: Re: Write Ahead Log > Local Time: January 9, 2018 7:07 PM > UTC Time: January 9, 2018 6:07 PM > From: [email protected] > To: [email protected] > > I'm not 100% sure what you mean by "what files can be checked". I think you > are looking for where the write ahead log and snapshot are stored. This > directory (optionally directories) are specified in the configuration file. > > First, there is the dataDir, which, according to the documentation is "the > location to store the in-memory database snapshots and, unless specified > otherwise, the transaction log of updates to the database". > > The "unless specified otherwise" refers to the optional configuration > dataLogDir. The dataDir always contains the snapshots in "snapshot.X" files > and if dataLogDir is not specified log files in "log.X" (X is a value that > ZooKeeper uses for keeping track of transactions). If dataLogDir is > specified, dataDir will only contain snapshots and dataLogDir will have the > log files. > > Small note, on ZooKeeper 3.4.11 there is a bug regarding dataLogDir not > functioning properly (see: > https://issues.apache.org/jira/browse/ZOOKEEPER-2960). This does not exist > prior to 3.4.11 and should be fixed in the next release. > > Thanks, > Abe > > On Tue, Jan 9, 2018, at 01:29, tj5527 wrote: > >> In addition to those great resources, what files can be checked for such >> mechanism (only write ahead log not other zk service components), >> particularly snapshot and log? >> Thanks for all the input. Much appreciated! >> >>> -------- Original Message -------- >>> Subject: Re: Write Ahead Log >>> Local Time: January 9, 2018 1:04 AM >>> UTC Time: January 9, 2018 12:04 AM >>> From: [email protected] >>> To: [email protected] >>> In addition to the great papers Ibrahim mentioned I'm a big fan of the >>> book: ZooKeeper: Distributed Process Coordination by Flavio Junqueira, >>> Benjamin Reed for getting a high level understanding of what's going on. >>> Thanks, >>> Abe >>> On Mon, Jan 8, 2018, at 05:27, Ibrahim El-sanosi (PGR) wrote: >>> >>>> Hi, >>>> You can read page 8 in [1] and section VII. EVALUATION in [2]. I hope >>>> these will be helpful. >>>> [1] Hunt, Patrick, et al. "ZooKeeper: Wait-free Coordination for >>>> Internet-scale Systems." USENIX annual technical conference. Vol. 8. >>>> 2010. >>>> [2] Junqueira, Flavio P., Benjamin C. Reed, and Marco Serafini. "Zab: >>>> High-performance broadcast for primary-backup systems." Dependable >>>> Systems & Networks (DSN), 2011 IEEE/IFIP 41st International Conference >>>> on. IEEE, 2011. >>>> Ibrahim >>>> -----Original Message----- >>>> From: tj5527 [mailto:[email protected]] >>>> Sent: 08 January 2018 13:14 >>>> To: [email protected] >>>> Subject: Write Ahead Log >>>> I heard that ZooKeeper uses Write Ahead Log for preserving operation >>>> information, and am interested in how it's implemented. But when >>>> checking ZooKeeper confluence wiki and searching the internet, I don't >>>> find much related documents. Only a few source files such as >>>> FileTxnLog.java that seems to be related with some lines written >>>> directly about write ahead log string. >>>> https://github.com/apache/zookeeper/blob/5c4e44332e55bbf21ca59583f3e8ca97fc4bb266/src/java/main/org/apache/zookeeper/server/persistence/FileTxnLog.java >>>> Is this the right place to start? What other resources available out >>>> there as reference? >>>> Thanks
