Question: Which of the following statements are true about reconfiguring a replica set? Check all that apply.
- The reconfiguration will always trigger an election
- The reconfiguration required the mongod servers to be restarted
- Servers can be either removed from teh replica set, or added (Ans)
- If a member of the replica set is not avialable, the replica set can still be reconfigured. (Ans)
Question: When might you want to use an arbiter? Check all that apply.
- To make an odd number of votes int eh replica set (Ans)
- To spread the replica set over more dataceters (Ans)
- To help in disaster recovery
- To protect against network splits (Ans)
- To query aggregation batch jobs
Question :Which values are valid “priority” values in a replia set configuration? Check all that apply.
- 0 (Ans)
- 500 (Ans)
- 88.4 (Ans)
- 88 (Ans)
Question: In which of the following scenarios does it make sense to use slave delay? Check all that apply.
- Prevent against a new client application release bug (Ans)
- During development when using experimental queries (Ans)
- For scaling the number of writes a replica set can handle
- For prduction level-live data queries
- As the primary backup
Question: Generally, is it typical for servers to have different vote counts?
- No (Ans)
Question : Imagine you’re using a 5-server replica set and you have critical inserts which you do not want the potential for a rollback to happen. You also have to consider that secondaries may be taken down from to time for maintenance, leaving you with a potential 4-server replica set. Which write concern is best suited for these critical inserts?
- w=majority (Ans)
Question: Write Concern is set at the DB level and every operation on this DB must use the same Write Concern:
- False (Ans)
Question: For getLastError / WriteConcern with w=3, if you have an arbiter, it counts as one of the 3.
- False (Ans)
Question: Does getLastError() need to be called if using default Write Concerns?
- No (Ans)
Question: What are some issues with using wtimeout? Check all that apply.
- A write can be made but getLastError() could reprot a failure (Ans)
- Each query coud potentially take the full duration of the wtimeout (Ans)
- Pile-ups of connections (Ans)
- Requests could hand indefinitely
- Doesn’t work with replica sets
Question: Using the following output from ls -R, which directories house the data files for a WiredTiger mongod process?
$ ls -R A C mongodA.log.2015-04-08T23-26-14 mongodB.log.2015-04-08T23-26-24 mongodC.log.2015-04-08T23-26-18 B mongodA.log mongodB.log mongodC.log ./A: WiredTiger WiredTiger.wt collection-4-4315177254347078174.wt index-3-4315177254347078174.wt mongod.lock WiredTiger.basecfg _mdb_catalog.wt collection-6-4315177254347078174.wt index-5-4315177254347078174.wt sizeStorer.wt WiredTiger.lock collection-0-4315177254347078174.wt collection-7-4315177254347078174.wt index-8-4315177254347078174.wt storage.bson WiredTiger.turtle collection-2-4315177254347078174.wt index-1-4315177254347078174.wt journal ./A/journal: WiredTigerLog.0000000001 WiredTigerPreplog.0000000001 ./B: _tmp journal local.0 local.1 local.ns mongod.lock storage.bson test.0 test.ns ./B/_tmp: ./B/journal: j._0 lsn ./C: WiredTiger _mdb_catalog.wt collection-7-6008883041206081919.wt index-5-6008883041206081919.wt storage.bson WiredTiger.basecfg collection-0-6008883041206081919.wt collection-9-6008883041206081919.wt index-8-6008883041206081919.wt WiredTiger.lock collection-2-6008883041206081919.wt index-1-6008883041206081919.wt journal WiredTiger.turtle collection-4-6008883041206081919.wt index-10-6008883041206081919.wt mongod.lock WiredTiger.wt collection-6-6008883041206081919.wt index-3-6008883041206081919.wt sizeStorer.wt ./C/journal: WiredTigerLog.0000000001 WiredTigerPreplog.0000000001
- A (Ans)
- C (Ans)
As directories A and C have WiredTiger data files, while directory B don’t, A and C stores WiredTiger data files.