Using NS3000/iX Network Services (36920-90008)

90 Chapter 5
Network File Transfer
Using Checkpoint and Restart with DSCOPY
Using Checkpoint and Restart with
DSCOPY
If you specify CHECKPT in the DSCOPY command line, the file transfer
will occur normally, but an additional handshake sequence will occur
between the source and target HP 3000 systems at periodic intervals
(optionally specified by you). If a failure occurs, it is then possible to
restart the transfer from the point where the last handshake took place.
A restart ID is a number that uniquely identifies a transfer. The restart ID
is returned to you before a file transfer actually begins. For example, if
a transfer were 44% complete when a handshake occurred, and the link
were to fail at some time before the next handshake, the transfer could
be restarted at a later time with at least 44% of the transfer already
complete.
To restart an aborted transfer, specify the keyword RESTART in the
DSCOPY command line along with the same restart ID that was
returned to you when CHECKPT was specified. You must be logged on to
the same local environment where CHECKPT was specified. NFT will
then attempt to restart the transfer from the point where the last
handshake sequence took place. The restarted transfer will continue to
be checkpointed and may be restarted in the event of a subsequent
failure.
In order to use CHECKPT/RESTART, the producer and consumer
environments cannot be the same; that is, checkpointing will not be
done for local transfers.
When you restart a transfer by using the RESTART option, you can also
invoke the CHECKPT option in order to modify the checkpoint interval; all
other options will be ignored.
NOTE You can access and change source and target files between
checkpointing and restarting. If you change the source file, you might
not get the exact file you want on the target side. In this case, you
should probably restart the entire transfer again.
New Restart Files Created During Checkpointed
Transfer
In order to store restart information that will survive a system failure,
NFT creates files called restart files. One file is created in the group and
account of each role being played by NFT, that is, initiator, producer,
and consumer. If more than one role is being played by a single
environment, the restart file will be shared. The name of the restart file
will be NFTRxx, where xx is a number from 1 to 99. These files will be
purged upon successful completion of the file transfer. If an