support checksums in HBase block

[jlei liu]

I use Hbase0.94.1 and  hadoop-0.20.2-cdh3u5.

The Hbase0.94.1 write checksums in HBase block, so we don't need to read
checksums from metadata file of block file. But I find the BlockSender
still read checksums from metadata file of block file every time,  so the
Hbase0.94.1 can't decrease the iops, that is right? If that is right,
should I set the  hbase.regionserver.checksum.verify property to false in
order to  avoid the Hbase0.94.1 to verify th checksum?


Thanks,
LiuLei