Re: Processing steps of NameNode & Secondary NameNode
Conceptually you can think of the namenode is similar to a journal file
system. For each write, it updates the in-memory data structure, persists
the operations on the stable storage (i.e., calling sync to flush the
buffer of the edit logs), then responds to the client.
Note that all writes are serialized, which means the writes are given a
total order. There are no consistent issues between multiple clients.
For question 3, the NN can writes to multiple edit logs with the same
content at the same time. This allows the operator to store a copy of edit
logs in NFS. In this case NN calls sync() for each edit log.
On Mon, Jan 27, 2014 at 4:12 AM, Amit Mittal <[EMAIL PROTECTED]> wrote:
NOTICE: This message is intended for the use of the individual or entity to
which it is addressed and may contain information that is confidential,
privileged and exempt from disclosure under applicable law. If the reader
of this message is not the intended recipient, you are hereby notified that
any printing, copying, dissemination, distribution, disclosure or
forwarding of this communication is strictly prohibited. If you have
received this communication in error, please contact the sender immediately
and delete it from your system. Thank You.