For the Hlog, I find an interesting problem. I set the optionallogflushinterval to 10000, that's 10 seconds; but it flushes with the interval of 1 hour.
After the hlog file generated, I stop hdfs and then kill hmaster and regionservers; then I start all again, the hmaster doesn't restore records from hlog, that's the record lost again. Is there something wrong? 2009/8/14 Chen Xinli <[email protected]> > Thanks Daniel. As you said the latest version has done much to avoid data > loss, would you pls give some example? > > I read the conf file and api, and find some functions related: > 1. in hbase-default.xml, "hbase.regionserver.optionallogflushinterval" > described as "Sync the HLog to the HDFS after this interval if it has not > accumulated enough entries to trigger a sync". I issued one update to my > table, but there's no hlog files after the specifed interval. > This setting doesn't work, or I make a misunderstanding? > > 2. HbaseAdmin.flush(tableOrRegionName). It seems that this function flush > the memcache to HStorefile. Should I call this function to avoid data loss > after several thousand updation? > > 3. In Htable, there is also a function flushCommits. Where does it flush > to? memcache or hdfs? > > Actually we have a crawler, and want to store webpages(about 1 billion) in > hbase. What shall we do to avoid data loss? Any suggestion is appreciated. > > By the way, we use hadoop 0.19.1 + hbase 0.19.3 > Thanks > > 2009/8/6 Jean-Daniel Cryans <[email protected]> > > Chen, >> >> The main problem is that appends are not supported in HDFS, HBase >> simply cannot sync its logs to it. But, we did some work to make that >> story better. The latest revision in the 0.19 branch and 0.20 RC1 both >> solve much of the data loss problem but it won't be near perfect until >> we have appends (supposed to be available in 0.21). >> >> J-D >> >> On Thu, Aug 6, 2009 at 12:45 AM, Chen Xinli<[email protected]> wrote: >> > Hi, >> > >> > I'm using hbase 0.19.3 on a cluster with 30 machines to store web data. >> > We got a poweroff days before and I found much web data lost. I have >> > searched google, and find it's a meta flush problem. >> > >> > I know there is much performance improvement in 0.20.0; Is the data lost >> > problem handled in the new version? >> > >> > -- >> > Best Regards, >> > Chen Xinli >> > >> > > > > -- > Best Regards, > Chen Xinli > -- Best Regards, Chen Xinli
