There's only one thing I know, that I constantly do.
I use the 'symmaskdb backup -sid XXX -f temp_bck_file' command.
And then I check the time of the backup using the 'symaudit list -sid XXX -action BegBckup' command.

You can also ask your local PSE to reset the clock with a symmetrix reboot .

Thanks, But I haven't permission to do this (I have read only permissions).
Actually, I try to find out which hosts need a resetting of their time...