Xiaofeng: Take a look at this: http://hbase.apache.org/book.html#hbase.regionserver.checksum.verify
Cheers On Tue, Jan 7, 2014 at 5:36 PM, LEI Xiaofeng <[email protected]> wrote: > I tried to set "BLOCKSIZE" to 0 when created table to tune the scan > performance, but it did not work. Another thing is what do you mean by > "turing HBase checksumming on"? I do not know how to do it. Could you give > mw some detailed information? > > Thanks > > > > -----原始邮件----- > > 发件人: "Doug Meil" <[email protected]> > > 发送时间: 2014年1月8日 星期三 > > 收件人: "[email protected]" <[email protected]>, "lars hofhansl" < > [email protected]> > > 抄送: > > 主题: Re: hbase read performance tuning failed > > > > > > In addition to what Lars just said about the blocksize, this is a similar > > question to another one that somebody asked, and it's always good to make > > sure that you understand where your data is. As a sanity check, make sure > > it's not all on one or two RSs (look at the hbase web pages or with tools > > like Hannibal). > > > > > > Also, you definitely want to to turn HBase checksumming on - and when you > > do so you'll need to re-create the HFiles (e.g., you can't just change > the > > config and bounce the HBase cluster). That's a significant reduction in > > I/O. > > > > Likewise, if you are doing a full-scan, make sure that you select only > the > > attributes you need... > > > > See this for more: http://hbase.apache.org/book.html#perf.reading > > > > > > > > > > > > On 1/7/14 1:24 PM, "lars hofhansl" <[email protected]> wrote: > > > > >If increasing hbase.client.scanner.caching makes no difference you have > > >another issue. > > >How many rows do you expect your to return? > > > > > >On contemporary hardware I manage to scan a few million KeyValues (i.e. > > >columns) per second and per CPU core. > > >Note that for scan performance you want to increase the BLOCKSIZE. > > > > > > > > >-- Lars > > > > > > > > > > > >________________________________ > > > From: LEI Xiaofeng <[email protected]> > > >To: [email protected] > > >Sent: Monday, January 6, 2014 11:06 PM > > >Subject: hbase read performance tuning failed > > > > > > > > >Hi, > > >I am running hbase-0.94.6-cdh4.5.0 and set up a cluster of 5 nodes. The > > >random read performance is ok, but the scan performance is poor. > > >I tried to increase "hbase.client.scanner.caching" to 100 to promote the > > >scan performance but it made no difference. And when I tried to make > > >smaller blocks by setting "BLOCKSIZE" when created tables to get better > > >random read performance it made no difference too. > > >So, I am wondering if anyone could give some advice to solve this > problem. > > > > > > > > > > > >Thanks > > > >
