[2.0-hotfix candidate] Offline upgrade hangs at cbtransfer converting sqlite file to couchstorefile

Have a 4 nodes cluster (http://172.23.96.12:8091). 1 default buckets 40G RAM on each node for the bucket. 200M items (920 G) in bucket. Resident is as low as 8.3%.
Try to do an offline upgrade from 181 to 2.0 build 1971:

[root@thor05 ~]# rpm -U couchbase-server-enterprise_x86_64_2.0.0-1971-rel.rpm
Stopping couchbase-server ...
Stopping couchbase-server
Upgrading couchbase-server ...
/opt/couchbase/bin/install/cbupgrade -c /opt/couchbase/var/lib/couchbase/config -a yes
Automatic mode: running without interactive questions or confirmations.
Upgrading your Couchbase Server to 2.0.0-1971-rel.
The upgrade process might take awhile.
Analysing...
Previous config.dat file is /opt/couchbase/var/lib/couchbase/config/config.dat
Target node: ns_1@172.23.96.14

Couchbase should not be running.
Please use: /etc/init.d/couchbase-server stop

Database dir: /data2

Buckets to upgrade: default

Checking disk space available for buckets in directory:
/data2
Free disk bucket space wanted: 494982651904.0
Free disk bucket space available: 570048225280
Free disk space factor: 2.0
Ok.

Analysis complete.

Copying /opt/couchbase/var/lib/couchbase/config/config.dat
cp /opt/couchbase/var/lib/couchbase/config/config.dat /opt/couchbase/bin/install/../../var/lib/couchbase/config/config.dat
Copying /opt/couchbase/var/lib/couchbase/ip
cp /opt/couchbase/var/lib/couchbase/ip /opt/couchbase/bin/install/../../var/lib/couchbase/ip
Ensuring bucket data directories.
Ensuring bucket data directory: /data2/default
mkdir -p /data2/default
Ensuring dbdir owner/group: /data2
chown -R couchbase:couchbase /data2
Ensuring dbdir owner/group: /opt/couchbase/var/lib/couchbase/data
chown -R couchbase:couchbase /opt/couchbase/var/lib/couchbase/data
Upgrading buckets.
Upgrading bucket: default
/opt/couchbase/bin/install/../cbtransfer /data2/default-data/default couchstore-files:///data2 -b default --source-vbucket-state=active --destination-vbucket-state=active
cbdbupgrade pid: 14416
[ ] 0.0% (0/49997137 msgs)

Offline upgrade hangs