PPRC uses one bit to represent a whole cylinder. So if only a single bit is changed in only one track in cylinder X, then bit X is turned on, which later will require the copying of all 15 tracks on cylinder X. If a fully populated EAV is ever available in beaucoup years from now, it will have 16 to the 7th power cylinders (ca. 268 million), and it will need the same number of bits, which is 33.5 million bytes. Maybe by then each bit will represent 1,000 cylinders.
Bill Fairchild Software Developer Rocket Software 275 Grove Street * Newton, MA 02466-2272 * USA Tel: +1.617.614.4503 * Mobile: +1.508.341.1715 Email: [email protected] Web: www.rocketsoftware.com -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Ron Hawkins Sent: Sunday, August 30, 2009 7:06 PM To: [email protected] Subject: Re: What happens in a DS8000 Metro Mirror (PPRC-Sync) config when the relationship between a volume pair is broken? Jan, It uses bitmaps, just like FlashCopy full version. Ron > > How does the system keep track of the source updates & changes in the mean > time, in order to resynchronize the volume pair later on? ---------------------------------------------------------------------- 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
