hbase-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Stack <st...@duboce.net>
Subject Re: Recovering from corrupt blocks in HFile
Date Wed, 18 Mar 2015 04:47:06 GMT
On Tue, Mar 17, 2015 at 5:04 PM, Mike Dillon <mike.dillon@synctree.com>
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.
St.Ack



> Thanks!
>
> -md
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message