Hi there- Glad to hear that the Arch chapter was helpful!
re: #1 "splits" The split won't be complete if the master isn't there. Good question, and the effects of the master not being up will be added to the book. re: #2. "RS monitoring" Good question, I'm not familiar with the specifics on that. (and more info will be added to the book too.) On 2/12/12 4:00 AM, "Eric Charles" <[email protected]> wrote: >Hi Doug, > >I was well thinking that master was in the play in case of region split >or problems. >I searched in the paper book I have, but didn't really find anything on >that. > >Luckily, it is well documented on >http://hbase.apache.org/book/regions.arch.html: > >- failover: "... The Master will detect that the RegionServer has failed. >" >- split: "...and then reports the split to the Master. " > >So master seems also to be involved in a regular splitting in addition >to RS lose. More questions: > >1.- What occurs if the region server can not report to Master after >splitting (for example if a guy like me killed the master to see 'what >happens'...). >2.- How does the master achieve the monitoring of its regions? (is there >an hearbeat generated by the regions or does Master pol). > >(searched around in books... but didn't find, maybe something to do with >CatalogJanitor?) > >Thx, >Eric > >On 11/02/12 20:12, Doug Meil wrote: >> >> Regarding the master being down, just be aware that if you lose an RS >>that >> you'll have issues because the master is what does the reassignment. >>Per >> the previous comments, at steady-state HBase can run without the master >>- >> there's an asterisk. >> >> >> >> >> On 2/11/12 11:31 AM, "Eric Charles"<[email protected]> wrote: >> >>> Funky, cause HBase is often presented as a 3-layers server model >>> zookeeper/master/region (root/meta in the regions bringing still more >>> fogs). >>> >>> Maybe the commonly understanding in the community is that HBase's >>> HMaster is like Hadoop's NameNode, which is not the case (NameNode's >>> failure will bring your cluster down, HMaster's failure will not...). >>> >>> Upon presentation simplification (via 'master' renaming, or at least >>>via >>> explanation emphases), having a more simple model such as the one >>> described in HBASE-3171 could help (this is my very short opinion, I >>> remember having read valid arguments against that model). >>> >>> client<->zk<->(master)<->region(root|master) >>> or >>> client<->zk<->region (+admin) >>> >>> the latter looks simpler, doesn't it? >>> >>> >>> Thx, >>> >>> Eric >>> >>> On 11/02/12 16:45, Stack wrote: >>>> 2012/2/11 Eric Charles<[email protected]>: >>>>> Hypothetical case (probably asked a number of time here, sorry...): >>>>> >>>>> Can a client correcty put, get, scan (no admins tasks such as create >>>>> table,...) with a HBase cluster having its HMaster process down ? >>>>> >>>> >>>> It can Eric. Kill your master and you can do all the above. >>>> St.Ack >>> >>> -- >>> eric | http://about.echarles.net | @echarles >>> >> >> > >-- >eric | http://about.echarles.net | @echarles >
