Can someone give me a detailed look at the HLog mechanism for 0.90 durablity? I recall that HBase committers claim that data will be truly durable in 0.90 after the client gets 'ok' acknowledgement from server, while it was not true in 0.20 (i.e., HBase may have the chance to lose the data even it says 'ok, I got it' to clients). Can someone give me some detailed info?
First, HLog can't seem to be flushed onto disk for each Put operation for performance reason (i.e., there exists time window when the log of a certain amout of hlog reside in the RegionServer's memory). If this understanding is correct, how are we going to assure total durablity? Secondly, would anyone share the change related to this between 0.90 and 0.20? Sean On Mon, Oct 11, 2010 at 1:58 PM, Ryan Rawson <[email protected]> wrote: > That is correct. But we are confident with the new durability changes and > other things 0.90 will be safer and faster than 0.20.6. > On Oct 11, 2010 4:51 PM, "Sean Bigdatafun" <[email protected]> > wrote: > > Thanks for clarifying this. > > > > But on the other hand, wow... that means that even I like the consistency > > enhancement in 0.90, I can not enjoy it if I have started using HBase > 0.20 > > on a production? > > > > > > > > > > > > On Thu, Sep 16, 2010 at 10:49 PM, Stack <[email protected]> wrote: > > > >> On Thu, Sep 16, 2010 at 10:22 PM, Todd Lipcon <[email protected]> > wrote: > >> > On Thu, Sep 16, 2010 at 8:51 PM, Stack <[email protected]> wrote: > >> > What about region ID naming changes? I don't think the new region IDs > >> would > >> > work in 0.20. > >> > > >> > >> True. > >> > >> So no going back from a 0.89+ to a 0.20 because format of region names > >> in filesystem has changed. > >> > >> St.Ack > >> >
