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https://issues.apache.org/jira/browse/BOOKKEEPER-126?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13229993#comment-13229993
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Rakesh R commented on BOOKKEEPER-126:
-------------------------------------
Yes, I agree with you. Its good, if able to handle the under-replication in
bookkeeper.
Following are the multiple thoughts comes to my mind, please go through this.
*Proposal-1)* As per my observation apart from 'bookie down' scenario(here it
can automate admin tool), the failure of anyone of the following 'flush()'
operation can leads to dataloss. Since it is async opr the client will be
unaware about these failures, further entries will override the data and so
only these entries needs to considered as 'under-replicated' and initiate
under-replica action.
+Bookie.java+
{noformat}
try {
ledgerCache.flushLedger(true);
} catch (IOException e) {
LOG.error("Exception flushing Ledger", e);
flushFailed = true;
}
try {
entryLogger.flush();
} catch (IOException e) {
LOG.error("Exception flushing entry logger", e);
flushFailed = true;
}
{noformat}
*Proposal-2)* Initiate the recovery whenever the client finds any missing
entries and then succesfully get the same from next bookie.
Still there is a gap of dataloss, say some data got lost/corrupt and no read
operation in near future.
*Proposal-3)* Daemon thread can be associated with every bookie and do
periodical scanning of its own ledgers and its entries, if found any errors can
contact ZK and tries to initiate replication of those entries.
In this case, it needs to build a mechanism to communicate between bookies, as
per my understanding there is no inter-bookie protocol exists. Also the cost of
scannig will be very high if the ledgers/entries are more :-)
-Rakesh
> EntryLogger doesn't detect when one of it's logfiles is corrupt
> ---------------------------------------------------------------
>
> Key: BOOKKEEPER-126
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-126
> Project: Bookkeeper
> Issue Type: Bug
> Reporter: Ivan Kelly
> Priority: Blocker
> Fix For: 4.1.0
>
>
> If an entry log is corrupt, the bookie will ignore any entries past the
> corruption. Quorum writes stops this being a problem at the moment, but we
> should detect corruptions like this and rereplicate if necessary.
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