Thank you, Raghu.
Then, when the percentage is below 0.999, how can you tell
if some datanodes are just slower than others or some of the data blocks are
lost?
I think "percentage 1" should have speacial meaning like
it guarantees integrity of data in HDFS.
If it's below 1, then the integrity is not said to be guaranteed.
Or are there any other useful means that a NameNode can fix the lost blocks,
so that it doesn't care even 0.1% of data is lost?
Thanks,
Manhee
----- Original Message -----
From: "Raghu Angadi" <[email protected]>
To: <[email protected]>
Sent: Wednesday, October 07, 2009 1:26 AM
Subject: Re: A question on dfs.safemode.threshold.pct
Yes, it is mostly geared towards replication greater than 1. One of the
reasons for waiting for this threshold is to avoid HDFS starting
unnecessary
replications of blocks at the start up when some of the datanodes are
slower
to start up.
When the replication is 1, you don't have that issue. A block either
exists
or does not.
Raghu
2009/10/5 Manhee Jo <[email protected]>
Hi all,
Why isn't the dfs.safemode.threshold.pct 1 by default?
When dfs.replication.min=1 with dfs.safemode.threshold.pct=0.999,
there might be chances for a NameNode to check in with incomplete data
in its file system. Am I right? Is it permissible? Or is it assuming that
replication would be always more than 1?
Thanks,
Manhee
