Hi Bill, thanks! Re. <<<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. >>>
Is the bitmap on cylinder level, or on track level? SG24-6787-04 DS8000 Copy Services for IBM System z (6 Februari 2009) pag. 213 paragraph 15.2? Volumes are in the suspended state when the primary and secondary storage subsystems cannot communicate anymore, or when the Metro Mirror pair is suspended manually. In this state, writes to the primary volume are not mirrored onto the secondary volume. The secondary volume becomes out-of-sync. During this time, Metro Mirror keeps a bitmap record of the changed tracks in the primary volume. Later, when the volumes are re-synchronized, only the tracks that were updated will be copied. Thruout the redbook at several places, it's always tracks who are mentioned in relationship with the bitmap. ??? Jan ---------------------------------------------------------------------- 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
