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https://issues.apache.org/jira/browse/HDFS-15438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17161369#comment-17161369
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Ayush Saxena commented on HDFS-15438:
-------------------------------------
Thanx [~AMC-team] for the report.
even if you get away here, you may get stuck below at L926 :
{code:java}
if (item.getErrorCount() >= getMaxError(item)) {
{code}
error count and max error both shall be zero and this condition shall become
true and ultimately you would land up setting an error.
Instead of this :
{code:java}
+ (item.getErrorCount() == 0 || item.getErrorCount() <
getMaxError(item))) {
{code}
Shouldn't we just have :
{code:java}
item.getErrorCount() <= getMaxError(item) {
{code}
and even tweak the if condition at L926 to remove the '=' sign?
cc [~aengineer] you wrote this up, any pointers.
> Setting dfs.disk.balancer.max.disk.errors = 0 will fail the block copy
> ----------------------------------------------------------------------
>
> Key: HDFS-15438
> URL: https://issues.apache.org/jira/browse/HDFS-15438
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: balancer & mover
> Reporter: AMC-team
> Priority: Major
> Attachments: HDFS-15438.000.patch
>
>
> In HDFS disk balancer, the config parameter
> "dfs.disk.balancer.max.disk.errors" is to control the value of maximum number
> of errors we can ignore for a specific move between two disks before it is
> abandoned.
> The parameter can accept value that >= 0. And setting the value to 0 should
> mean no error tolerance. However, setting the value to 0 will simply don't do
> the block copy even there is no disk error occur because the while loop
> condition *item.getErrorCount() < getMaxError(item)* will not satisfied.
> {code:java}
> // Gets the next block that we can copy
> private ExtendedBlock getBlockToCopy(FsVolumeSpi.BlockIterator iter,
> DiskBalancerWorkItem item) {
> while (!iter.atEnd() && item.getErrorCount() < getMaxError(item)) {
> try {
> ... //get the block
> } catch (IOException e) {
> item.incErrorCount();
> }
> if (item.getErrorCount() >= getMaxError(item)) {
> item.setErrMsg("Error count exceeded.");
> LOG.info("Maximum error count exceeded. Error count: {} Max error:{}
> ",
> item.getErrorCount(), item.getMaxDiskErrors());
> }
> {code}
> *How to fix*
> Change the while loop condition to support value 0.
>
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