Dear team,
we have implemented Co:Z SFTP on Mainframe server and connecting from Non-Mainframe server (Linux).
But while downloading the file from Mainframe to our Linux server we observed that downloading time is almost 7-8 times than FTP downloading time.
Can you please confirm, the higher downloading time is expected compared to FTP downloading time ?
Note :
Server : Mainframe - Co:Z SFTP implemented
Client : Non-Mainframe - Co:Z SFTP not implemented
Establishing the connection from Non-mainframe to Mainframe for reading the file.
Thanks,
UVK
Higher downloading time with Co:Z SFTP
Re: Higher downloading time with Co:Z SFTP
When you connect to Co:Z SFTP server from a non-mainframe sftp client, there will be three significant address spaces for each connection:
1) The OMVS address space which runs the IBM OpenSSH "/usr/sbin/sshd" program
2) The OMVS address space which runs /bin/sh (the z/OS UNIX shell), which runs the Co:Z sftp-server.sh startup script
3) The OMVS address space which runs <coz_dir>/bin/sftp-server (the Co:Z SFTP server program)
#1 normally accounts for 90% or more of the CPU time.
#2 doesn't do much or use any significant resources
#3 does file/dataset I/O processing, character conversion, etc
When comparing SFTP to standard FTP, the following explain performance differences:
a) Increased CPU due to SSH encryption and (to a much lesser extent) packet processing may be a bottleneck in your system if resources are not available.
b) The communication ports are different, so your network path / firewall rules /etc might be different
Have you tuned IBM Ported Tools OpenSSH to exploit ICSF for crypto?
See the appropriate "Quick Install" guide for your release here: http://dovetail.com/docs/coz/coz_index.html
If you haven't done this, you can typically save 50% of the overall CPU time by following these steps.
One quick test that can often be revealing is to do a big download from z/OS to z/OS on the same LPAR. If this runs with good throughput, then your problem is probably not with a CPU bottleneck.
If you are interested in additional assistance with tuning your system, you may wish to consider our Enterprise LIcense and Support agreements. Please send us an email at info@dovetai.com if you would like more information.
1) The OMVS address space which runs the IBM OpenSSH "/usr/sbin/sshd" program
2) The OMVS address space which runs /bin/sh (the z/OS UNIX shell), which runs the Co:Z sftp-server.sh startup script
3) The OMVS address space which runs <coz_dir>/bin/sftp-server (the Co:Z SFTP server program)
#1 normally accounts for 90% or more of the CPU time.
#2 doesn't do much or use any significant resources
#3 does file/dataset I/O processing, character conversion, etc
When comparing SFTP to standard FTP, the following explain performance differences:
a) Increased CPU due to SSH encryption and (to a much lesser extent) packet processing may be a bottleneck in your system if resources are not available.
b) The communication ports are different, so your network path / firewall rules /etc might be different
Have you tuned IBM Ported Tools OpenSSH to exploit ICSF for crypto?
See the appropriate "Quick Install" guide for your release here: http://dovetail.com/docs/coz/coz_index.html
If you haven't done this, you can typically save 50% of the overall CPU time by following these steps.
One quick test that can often be revealing is to do a big download from z/OS to z/OS on the same LPAR. If this runs with good throughput, then your problem is probably not with a CPU bottleneck.
If you are interested in additional assistance with tuning your system, you may wish to consider our Enterprise LIcense and Support agreements. Please send us an email at info@dovetai.com if you would like more information.