Thanks for your replies. Few seconds I was feeling unsecured ;) Seems the default period for the DataBlockScanner is 3 weeks: static final long DEFAULT_SCAN_PERIOD_HOURS = 21*24L;
And I have not found anyway to modify that. I will continue to search and might drop a msg on hadoop list if I still don't find. Thanks, JM 2013/2/26 Anoop Sam John <[email protected]>: > I was typing a reply and by the time Liang replied :) > Ya agree with him. It is only the HDFS client (At RS) not doing the checksum > verification based on the HDFS stored checksum. > Instead HBase only check for the correctness by comparing with stored > checksum values. Still the periodic operation of block scanning at HDFS will > continue. We can turn this OFF by configuring this period with a -ve value I > think. > > -Anoop- > ________________________________________ > From: 谢良 [[email protected]] > Sent: Tuesday, February 26, 2013 5:54 PM > To: [email protected] > Subject: 答复: HBase CheckSum vs Hadoop CheckSum > > comments in line > > Regards, > Liang > ________________________________________ > 发件人: Jean-Marc Spaggiari [[email protected]] > 发送时间: 2013年2月26日 20:03 > 收件人: user > 主题: HBase CheckSum vs Hadoop CheckSum > > Hi, > > Quick question. > > When we are activating the short circuit read in HBase, it's > recommanded to activate the HBase checksum instead of Hadoop ones. > This is done in the HBase configuration. > > I'm wondering what is the impact on the DataNode Block Scanner. > > Is it going to be stopped because checksums can't be used anymore? Or > will Hadoop continue to store its own checksum and use them but it's > just that HBase will not look at them anymore and will store and use > its own checksums? > [liang xie]: yes, still store checksum in meta file in current community > version. > btw, facebook's hadoop-fb20 branch has an inline checksum feature,IIRC > > Since it's an HBase configuration (hbase.regionserver.checksum.verify) > I'm expecting this to not have any impact on the Block Scanner, but > I'm looking for a confirmation. > [liang xie]: yes, no impact on hdfs's DataBlockScanner, you can check > detail in datanode's BlockPoolSliceScanner.verifyBlock(): > blockSender = new BlockSender(block, 0, -1, false, true, true, > datanode, null); > > > Thanks, > > JM
