Thanks J-D! Yeah, what you describe below is also something that I think Edward pointed out in some of his slides - that you could route all requests for X to the place where X is when you don't want to have X cached (in app-level caches and/or OS-level caches) on multiple servers, but that sometimes you do want to "waste" memory like this because you have to spread requests for X over more servers.
Are these two modes going to be supported in HBase? Thanks, Otis ---- We're hiring HBase hackers for Data Mining and Analytics http://blog.sematext.com/2011/04/18/hiring-data-mining-analytics-machine-learning-hackers/ ----- Original Message ---- > From: Jean-Daniel Cryans <[email protected]> > To: [email protected] > Sent: Tue, April 19, 2011 5:10:07 PM > Subject: Re: Region replication? > > We have something on the menu: > https://issues.apache.org/jira/browse/HBASE-2357 Coprocessors: Add > read-only region replicas (slaves) for availability and fast region > recovery > > Something to keep in mind is that you have to cache the data for each > replica, so a row could be in 3 different caches (which also have to > be warmed). I guess this is useful for very hot rows compared to a > much larger read distribution, in which case you'd really want to > cache it only once else you'd need 3x the memory to hold your dataset > in cache. > > J-D > > On Tue, Apr 19, 2011 at 12:33 PM, Otis Gospodnetic > <[email protected]> wrote: > > Hi, > > > > I imagine lots of HBase folks have read or will want to read > > http://blog.milford.io/2011/04/why-i-am-very-excited-about-datastaxs-brisk/ , > > including comments. > > > > My question has to do with one of the good comments from Edward Capriolo, >who > > pointed out that some of the Configurations he described in his Cassandra > as > > Memcached talk ( > > http://www.edwardcapriolo.com/roller/edwardcapriolo/resource/memcache.odp ) > > >are > > not possible with HBase because in HBase there is only 1 copy of any given > > Region and it lives on a single RegionServer (I'm assuming this is >correct?), > > thus making it impossible to spread reads of data from one Region over >multiple > > RegionServers: > > > > >http://blog.milford.io/2011/04/why-i-am-very-excited-about-datastaxs-brisk/#comment-187253604 > > > > > > > So I poked around on search-hadoop.com and JIRA, and looked at > > http://hbase.apache.org/book/regions.arch.html to see about this limitation, > > whether it's even mentioned as a limitation, whether there are plans to >change > > it or if there are some configuration alternatives that would make some of >those > > configurations described by Ed possible with HBase, but I actually didn't >find > > any explicit information about that. > > > > Would anyone care to comment? :) > > > > Many thanks, > > Otis > > -- > > We're hiring HBase hackers for Data Mining and Analytics > > >http://blog.sematext.com/2011/04/18/hiring-data-mining-analytics-machine-learning-hackers/ > > > >
