On Tue, Mar 17, 2015 at 9:47 PM, Stack <[email protected]> wrote: > On Tue, Mar 17, 2015 at 5:04 PM, Mike Dillon <[email protected]> > wrote: > >> Hi all- >> >> I've got an HFile that's reporting a corrupt block in "hadoop fsck" and >> was >> hoping to get some advice on recovering as much data as possible. >> >> When I examined the blk-* file on the three data nodes that have a replica >> of the affected block, I saw that the replicas on two of the datanodes had >> the same SHA-1 checksum and that the replica on the other datanode was a >> truncated version of the replica found on the other nodes (as reported by >> a >> difference at EOF by "cmp"). The size of the two identical blocks is >> 67108864, the same as most of the other blocks in the file. >> >> Given that there were two datanodes with the same data and another with >> truncated data, I made a backup of the truncated file and dropped the >> full-length copy of the block in its place directly on the data mount, >> hoping that this would cause HDFS to no longer report the file as corrupt. >> Unfortunately, this didn't seem to have any effect. >> >> > That seems like a reasonable thing to do. > > Did you restart the DN that was serving this block before you ran fsck? > (Fsck asks namenode what blocks are bad; it likely is still reporting off > old info). > > > >> Looking through the Hadoop source code, it looks like there is a >> CorruptReplicasMap internally that tracks which nodes have "corrupt" >> copies >> of a block. In HDFS-6663 <https://issues.apache.org/jira/browse/HDFS-6663 >> >, >> a "-blockId" parameter was added to "hadoop fsck" to allow dumping the >> reason that a block ids is considered corrupt, but that wasn't added until >> Hadoop 2.7.0 and our client is running 2.0.0-cdh4.6.0. >> >> > Good digging. > > > >> I also had a look at running the "HFile" tool on the affected file (cf. >> section 9.7.5.2.2 at http://hbase.apache.org/0.94/book/regions.arch.html >> ). >> When I did that, I was able to see the data up to the corrupted block as >> far as I could tell, but then it started repeatedly looping back to the >> first row and starting over. I believe this is related to the behavior >> described in https://issues.apache.org/jira/browse/HBASE-12949 > > > > So, your file is 3G and your blocks are 128M? > > The dfsclient should just pass over the bad replica and move on to the > good one so it would seem to indicate all replicas are bad for you. > > If you enable DFSClient DEBUG level logging it should report which blocks > it is reading from. For example, here I am reading the start of the index > blocks with DFSClient DEBUG enabled but I grep out the DFSClient emissions > only: > > [stack@c2020 ~]$ ./hbase/bin/hbase --config ~/conf_hbase > org.apache.hadoop.hbase.io.hfile.HFile -h -f > /hbase/data/default/tsdb/3f4ea5ea14653cee6006f13c7d06d10b/t/68b00cb158aa4d839f1744639880f362|grep > DFSClient > 2015-03-17 21:42:56,950 DEBUG [main] util.ChecksumType: > org.apache.hadoop.util.PureJavaCrc32 available > 2015-03-17 21:42:56,952 DEBUG [main] util.ChecksumType: > org.apache.hadoop.util.PureJavaCrc32C available > SLF4J: Class path contains multiple SLF4J bindings. > SLF4J: Found binding in > [jar:file:/home/stack/hbase-1.0.1-SNAPSHOT/lib/slf4j-log4j12-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class] > SLF4J: Found binding in > [jar:file:/home/stack/hadoop-2.7.0-SNAPSHOT/share/hadoop/common/lib/slf4j-log4j12-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class] > SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an > explanation. > SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory] > 2015-03-17 21:42:58,082 INFO [main] hfile.CacheConfig: > CacheConfig:disabled > 2015-03-17 21:42:58,126 DEBUG [main] hdfs.DFSClient: newInfo = > LocatedBlocks{ > fileLength=108633903 > underConstruction=false > > blocks=[LocatedBlock{BP-410607956-10.20.84.26-1391491814882:blk_1078238905_1099516142201; > getBlockSize()=108633903; corrupt=false; offset=0; > locs=[DatanodeInfoWithStorage[10.20.84.27:50011,DS-21a30dbf-5085-464d-97f4-608a0b610c49,DISK], > DatanodeInfoWithStorage[10.20.84.31:50011,DS-aa69a8eb-2761-40c7-9b18-9b887c8e5791,DISK], > DatanodeInfoWithStorage[10.20.84.30:50011 > ,DS-03a89da2-8ab6-465a-80bb-c83473f1dc8b,DISK]]}] > > lastLocatedBlock=LocatedBlock{BP-410607956-10.20.84.26-1391491814882:blk_1078238905_1099516142201; > getBlockSize()=108633903; corrupt=false; offset=0; > locs=[DatanodeInfoWithStorage[10.20.84.30:50011,DS-21a30dbf-5085-464d-97f4-608a0b610c49,DISK], > DatanodeInfoWithStorage[10.20.84.31:50011,DS-aa69a8eb-2761-40c7-9b18-9b887c8e5791,DISK], > DatanodeInfoWithStorage[10.20.84.27:50011 > ,DS-03a89da2-8ab6-465a-80bb-c83473f1dc8b,DISK]]} > isLastBlockComplete=true} > 2015-03-17 21:42:58,132 DEBUG [main] hdfs.DFSClient: Connecting to > datanode 10.20.84.27:50011 > 2015-03-17 21:42:58,281 DEBUG [main] hdfs.DFSClient: Connecting to > datanode 10.20.84.27:50011 > 2015-03-17 21:42:58,375 DEBUG [main] hdfs.DFSClient: newInfo = > LocatedBlocks{ > fileLength=108633903 > underConstruction=false > > blocks=[LocatedBlock{BP-410607956-10.20.84.26-1391491814882:blk_1078238905_1099516142201; > getBlockSize()=108633903; corrupt=false; offset=0; > locs=[DatanodeInfoWithStorage[10.20.84.30:50011,DS-21a30dbf-5085-464d-97f4-608a0b610c49,DISK], > DatanodeInfoWithStorage[10.20.84.31:50011,DS-aa69a8eb-2761-40c7-9b18-9b887c8e5791,DISK], > DatanodeInfoWithStorage[10.20.84.27:50011 > ,DS-03a89da2-8ab6-465a-80bb-c83473f1dc8b,DISK]]}] > > lastLocatedBlock=LocatedBlock{BP-410607956-10.20.84.26-1391491814882:blk_1078238905_1099516142201; > getBlockSize()=108633903; corrupt=false; offset=0; > locs=[DatanodeInfoWithStorage[10.20.84.27:50011,DS-21a30dbf-5085-464d-97f4-608a0b610c49,DISK], > DatanodeInfoWithStorage[10.20.84.31:50011,DS-aa69a8eb-2761-40c7-9b18-9b887c8e5791,DISK], > DatanodeInfoWithStorage[10.20.84.30:50011 > ,DS-03a89da2-8ab6-465a-80bb-c83473f1dc8b,DISK]]} > isLastBlockComplete=true} > 2015-03-17 21:42:58,376 DEBUG [main] hdfs.DFSClient: Connecting to > datanode 10.20.84.30:50011 > 2015-03-17 21:42:58,381 DEBUG [main] hdfs.DFSClient: Connecting to > datanode 10.20.84.27:50011 > > Do you see it reading from 'good' or 'bad' blocks? > > I added this line to hbase log4j.properties to enable DFSClient DEBUG: > > log4j.logger.org.apache.hadoop.hdfs.DFSClient=DEBUG > > On HBASE-12949, what exception is coming up? Dump it in here. > > > >> My goal is to determine whether the block in question is actually corrupt >> and, if so, in what way. > > > What happens if you just try to copy the file local or elsewhere in the > filesystem using dfs shell. Do you get a pure dfs exception unhampered by > hbaseyness? > > > >> If it's possible to recover all of the file except >> a portion of the affected block, that would be OK too. > > > I actually do not see a 'fix' or 'recover' on the hfile tool. We need to > add it so you can recover all but the bad block (we should figure how to > skip the bad section also). > > > >> I just don't want to >> be in the position of having to lose all 3 gigs of data in this particular >> region, given that most of it appears to be intact. I just can't find the >> right low-level tools to let me determine the diagnose the exact state and >> structure of the block data I have for this file. >> >> > Nod. > > > >> Any help or direction that someone could provide would be much >> appreciated. >> For reference, I'll repeat that our client is running Hadoop >> 2.0.0-cdh4.6.0 >> and add that the HBase version is 0.94.15-cdh4.6.0. >> >> > See if any of the above helps. I'll try and dig up some more tools in > meantime. >
I asked some folks who know better and they suggested and asked various: + Are you doing short-circuit reads? If so, this may be frustrating DFSClient moving to good block. + In later versions of hadoop (cdh5.2.1 for example), you could do hdfs dfsadmin -triggerBlockReport DN:PORT.. this is probably of no use to you so you might have to restart the DN to have NN notice change in blocks. + This might be better than what I suggested above: HADOOP_ROOT_LOGGER="TRACE,console" hdfs dfs -cat /interesting_file St.Ack
