Eric, Bruce is saying that the effective transfer from the controller to the tape drive is 27 MB/sec. Thus, when the ESCON channel can't provide nearly that thruput, the tape drive ends up waiting for the channel.
Rex -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Eric N. Bielefeld Sent: Monday, May 15, 2006 5:07 PM To: [email protected] Subject: Re: question to backup on 3590 Bruce, I thought the compression took place in the control unit, so the full amount of data went over the escon channel, and was compressed by the hardware before writing or reading. How does that triple the effective tape rate to 27MB/sec. over the escon channel? Eric Bielefeld Sr. z/OS Systems Programmer Milwaukee Wisconsin 414-475-7434 ----- Original Message ----- From: "Bruce Black" <[EMAIL PROTECTED]> > On the tape, the max sustained rate is 9 MB/sec, but compression > effectively triples the data rate (on the average, compression ratios > vary) so the effective tape rate is around 27MB/sec. this is a good > argument for FICON channels on 3590 drives, to make the channel faster > than the tape. > > Bruce A. Black > Senior Software Developer for FDR > Innovation Data Processing 973-890-7300 > personal: [EMAIL PROTECTED] > sales info: [EMAIL PROTECTED] > tech support: [EMAIL PROTECTED] > web: www.innovationdp.fdr.com ---------------------------------------------------------------------- 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
