In this case a file is zip and then ftp'd. The applications folk use tape to avoid calculating dasd space and to not tie up limited dasd. Hardware compression is irrelevant.
-----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of David Speake Sent: Tuesday, February 14, 2006 11:51 AM To: IBM-MAIN@BAMA.UA.EDU Subject: Re: ZIP/390 with Virtual Tapes Why ZIP to ANY 3490 or 3590 tape? The tape unit itself compresses before writing. The VT seems to do it twice. Once to see if it has all the data that would fit on a "normal" 3490 cart. I guess it writes the compressed data to its internal dasd. It would seem strange to compress data just to make it look like a 3490 full cart to a TMS and then throw the compressed data away and write the long stuff to internal dasd. I don't know if the VTM expands the data as it reads from dasd before sending it to the 3590 as a stacked vol. In any case, the 3590 compresses it again. ZIP seems like a waste of cycles unless you have channel bandwidth problems. DSS ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
