Any replication support in 0.21 won't be even close to 2PC, since it's more or less a nightmare.
But your approach sounds good in the mean time. Good luck! -ryan On Tue, Jun 16, 2009 at 2:35 PM, Fred Zappert <[email protected]> wrote: > Ryan, > > Thanks for the information. > > In terms of replication support, I had already recommended replication by > having the transactions processed at both data centers by a message queue > (top-level-replication) that did not require data-base level replication. > > I've seen to many limitations on those over the years in the RDMS field to > want to deal with that again. > > This application is amenable to that approach since most of it involves > data > collection (inserts and simple updates) with no requirement for two-phase > commits that we've discovered yet. > > Regards, > > Fred. > > On Tue, Jun 16, 2009 at 4:27 PM, Ryan Rawson <[email protected]> wrote: > > > i havent heard of it, but it would be nice :-) > > > > > > > > On Tue, Jun 16, 2009 at 2:21 PM, Ski Gh3 <[email protected]> wrote: > > > > > I thought HDFS will fix the namenode as a SPOF just as HBase fix the > > master > > > in 0.20, so that is still not there yet? > > > > > > On Tue, Jun 16, 2009 at 2:04 PM, Ryan Rawson <[email protected]> > wrote: > > > > > > > HBase itself doesn't strictly have any SPOF in 0.20. Multiple master > > > > failover, etc. > > > > > > > > HBase depends on HDFS, which does have a SPOF in it's namenode. If > > that > > > > goes down, everything is down. Generally speaking, namenode is > > reliable, > > > > but the hardware is the issue. You can have a quick recovery, but > > still > > > > outage. > > > > > > > > > > > > HBase isn't explicitly designed to run across a WAN split between 2 > > > > datacenters. It's certainly possible, but during certain link-down > > > > scenarios you are looking at cluster splits. HBase master will > decide > > > > those > > > > regionservers no longer reachable have died, and HDFS will assume > those > > > > datanodes lost are gone, and start to replicate data. > > > > > > > > In HBase 0.21, we are hoping to have replication support between > > > clusters. > > > > > > > > -ryan > > > > > > > > > > > > On Tue, Jun 16, 2009 at 1:53 PM, Fred Zappert <[email protected]> > > > wrote: > > > > > > > > > Hi, > > > > > > > > > > We're considering HBase for a customer-facing SaaS. I saw some > > > > references > > > > > to Master instance, and failure/failover scenarios on this list. > > > > > > > > > > We would be running this across at least two data centers in > > different > > > > > cities or sates. > > > > > > > > > > Which leads to the following questions: > > > > > > > > > > 1. Are there any single points of failure in an HBase > configuration. > > > > > > > > > > 2: What would be the impact of one data center being down? > > > > > > > > > > 3: What would be the recovery time and procedure to restore normal > > > > > operation > > > > > on a new master? > > > > > > > > > > There are approximately 4M transactions/day > > > > > > > > > > Thanks, > > > > > > > > > > Fred. > > > > > > > > > > > > > > >
