Does it take a long time for upgrading elasticsearch version 1.4.4 to version 2.4.4?

when i uprading my elasticsearch cluster from 1.4.4 to 2.4.4, i wait for a long time and the nodes do not setup cluster.

i use netstat to check listening port, and i find all nodes do not listem port 9300 and 9200

in the log, there are many log messages like:

[2016-10-15 19:22:22,559][INFO ][common.util ] [netflow_log_v3-sin01-2016.08.03][4] move file [_1oo_es090_0.blm] size: [332878]

[2016-10-15 19:22:52,597][INFO ][common.util ] [netflow_log_v3-sin01-2016.08.03][4] fsync files
[2016-10-15 19:22:52,597][INFO ][common.util ] [netflow_log_v3-sin01-2016.08.03][4] syncing [segments.gen]
[2016-10-15 19:22:52,597][INFO ][common.util ] [netflow_log_v3-sin01-2016.08.03][4] syncing [_26h_es090_0.doc]

are there some errors ? or it is normal?

Looks normal.

How long is a "long time"?

yes, it looks like needing to make some data format transformations if upgrading 1.4.4 to 2.4.1.

i started the cluster at about time 19:00 yesterday, and when i checked it on morning of today, the cluster had setup!

What is exactly happening on data only nodes when it is moving and fsyncing files ? We are seeing the similar issue and the back to service time for the cluster is very high because of this. Is there a way the progress can be monitored ?