The following quick and easy techniques may improve your performance rates when transferring files remotely to or from NAS.
This can increase your transfer rates by 5x, compared to older methods such as 3des.
Transfer files from the /nobackup filesystem, which is often faster than the locally mounted disks.
If you are using scp and your data is compressible, try adding the -C option to enable file compression, which can sometimes double your performance rates:
% scp -C filename user@remote_host.com:
For SCP transfers, use a low-process-overhead cipher such as aes128-gcm@openssh.com or arcfour:
If you are transferring files from Lou, make sure they are online, rather than on the tape archive, before you perform the transfer operation.
Note: If you use the shiftc command to transfer your files, it will automatically bring any files that are on the tape archive online before it transfers them. If you are not using shiftc, use the following DMF commands to determine the location of your files and bring them online if necessary:
% dmls -al filename # show the status of your file.
% dmget filename # retrieve your file from tape prior to transferring.
For a full list of DMF commands, see DMF commands.
If you are transferring many small files, try using the tar command to compress them into a single file prior to transfer. Copying one large file is faster than transferring many small files.
For files larger than a gigabyte, we recommended using the Shift Transfer Tool, which can achieve much faster rates than single-stream applications such as scp or rsync.
If you continue experiencing slow transfers and want to work with a network engineer to help improve file transfers, please contact the NAS Control Room at support@nas.nasa.gov.
