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Posted to hdfs-user@hadoop.apache.org by Praveen Sripati <pr...@gmail.com> on 2012/01/08 04:43:54 UTC
NameNode Safe Mode and CheckPointing
When the checkpointing starts, the primary namenode starts a new edits
file. During the checkpointing process will the namenode go into safe
mode? According
to the Hadoop - The Definitive Guide
> The schedule for checkpointing is controlled by two configuration
parameters. The secondary namenode checkpoints every hour
(fs.checkpoint.period in seconds) or sooner if the edit log has reached 64
MB (fs.checkpoint.size in bytes), which it checks every five minutes.
Regards,
Praveen
Re: NameNode Safe Mode and CheckPointing
Posted by Harsh J <ha...@cloudera.com>.
Praveen,
You just answered yourself. If newer edits (from checkpoint-init) are being made to go to a newer edits file, then why do you imagine there'll be a problem with file modifications? To remind, the FS structure is also held in memory and reflects the current state. Checkpointing is done over the persisted elements.
P.s. Dev. questions are best asked on hdfs-dev so it reaches the right audience.
On 08-Jan-2012, at 10:57 AM, Praveen Sripati wrote:
> During the time the NN stops writing to the old edits file and creates a new edit file, will the file modifications work or not? Curious, how this is handled in the code.
>
> Praveen
>
> On Sun, Jan 8, 2012 at 9:34 AM, Harsh J <ha...@cloudera.com> wrote:
> Praveen,
>
> On 08-Jan-2012, at 9:13 AM, Praveen Sripati wrote:
>
>> When the checkpointing starts, the primary namenode starts a new edits file. During the checkpointing process will the namenode go into safe mode?
>
> No.
>
Re: NameNode Safe Mode and CheckPointing
Posted by Praveen Sripati <pr...@gmail.com>.
During the time the NN stops writing to the old edits file and creates a
new edit file, will the file modifications work or not? Curious, how this
is handled in the code.
Praveen
On Sun, Jan 8, 2012 at 9:34 AM, Harsh J <ha...@cloudera.com> wrote:
> Praveen,
>
> On 08-Jan-2012, at 9:13 AM, Praveen Sripati wrote:
>
> When the checkpointing starts, the primary namenode starts a new edits
> file. During the checkpointing process will the namenode go into safe
> mode?
>
>
> No.
>
Re: NameNode Safe Mode and CheckPointing
Posted by Harsh J <ha...@cloudera.com>.
Praveen,
On 08-Jan-2012, at 9:13 AM, Praveen Sripati wrote:
> When the checkpointing starts, the primary namenode starts a new edits file. During the checkpointing process will the namenode go into safe mode?
No.