+1. I think this is a very useful improvement. In the past when I
wanted to add a new snapshot field which needs to be persisted in
fsimage, I found that I would break the binary compatibility thus some
workaround had to be used (see HDFS-5428). Now protobuf gives us this
flexibility to make these changes in the fsimage.

I've actively reviewed the jiras in the HDFS-5698 and I believe it's
good to be merged to trunk now. We already have enough unit tests to
cover the fsimage saving/loading and even offline image viewer (e.g.,
TestSnapshot, TestRenameWithSnapshots, and
TestCheckPointForSecurityTokens). A lot of system tests with the new
fsimage have also been done while doing the performance tests. A very
good plan to improve the performance has been stated in the design
document (some results based on the improvement have even been
provided also), and I think we can keep working on them in trunk.


On Thu, Jan 30, 2014 at 2:37 PM, Haohui Mai <[EMAIL PROTECTED]> wrote:

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