Reading Tape Files using Co:Z SFTP

[vinayuppala]

Hi,

We have established Co:Z SFTP in mainframe server and trying to read files from our local server.
We are able to read files from Mainframe server to our local server without any issues using below command
“ get //Mainframe_fileName Local_FileName ”

But we are unable to read Tape data sets from Mainframe to our local server using above get command,
Could you please confirm Co:Z SFTP will support reading tape files,
if Yes, can you please provide me the command to read the tape files (if it is different from above get command)


Thanks,
Vinay Uppala

[dovetail]

Yes, you can allocate tape datasets with Co:Z SFTP.
You will need both mount authority for the userid, and you also need to enable the "mount" option:

ls /+mount

[vinayuppala]

Thanks Admin,

Another concern here

Will it affect the downloading time/performance, if we use "ls /+mount" to read tape dataset from Mainframe server to Non mainframe server.

When we used "ls /+mount" command to read the tape file from Mainframe server, it is taking almost 9 times than existing FTP connection transfer time.

Thanks,
Vinay Uppala

[dovetail]

If you are comparing the throughput (time) with unencrypted FTP, then there could be several reasons why there is a big difference:

1) SSH uses a single port, 22. Your network path (firewalls, routers, etc) may be different or there may be rules in place that favor regular FTP traffice over SSH. But this is not normally the reason.

2) CO:Z SFTP uses IBM Ported Tools OpenSSH, which does the low level ssh socket communications and encryption. There is significantly more involved in using encrypted SSH over uncrypted FTP. Your throughput difference may be because you are being limited by CPU availability or WLM settings.

The first step is to have your systems programmer figure out if the SFTP job is being throttled due to CPU. RMFIII or similar can be used.
For looking at CPU, there will be several address spaces for each CO:Z SFTP session:

1) The OMVS address space which will runs <coz>/bin/sftp-server
2) The OMVS SSHD address space which runs the Unix shell (/bin/sh) used to start Co:Z sftp server. This doesn't use any resources to speak of.
3) The OMVS SSHD address space which runs /usr/sbin/sshd, which is the IBM OpenSSH server.

#3 (IBM OpenSSH server) normally accounts for 90% of the CPU time

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.

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.