Bruce, There are two ways for Shadowimage to split with IO Consistency. One is to use the At-Time split function in BCM, and the other is to use Shadowimage Consistency Groups.
The At-Time Split function works the same way as Nanocopy, in that it posts a future time in the controller when you want the Point In Time to be, and when IO arrives with a timestamp greater than or equal to that time it will trigger the suspend. It's a proven, non-disruptive method we have been using to get P-i-T since we introduced Nanocopy on the 7700E. The neat thing about At-Time split is it can create P-i-T consistency across an unlimited number of Controllers and Volumes. There is no communication software or IO suspension required because the DFP timestamps are used. It can also be used for TrueCopy. Shadowimage Consistency Groups can be used when the OS does not support Timestamps (like VSE) or you want to split off a Shadowimage in a Remote CU without stopping TrueCopy. In this case the Controller will block writes at the Storage Port for the volumes in the Shadowimage Consistency Group. Doing this with BCM software makes the duration of the first to last suspend command many, many, many (did I mention many) times faster than using the ANTRQST interface (PPRC, CC and FC). Thus the time to write blockade is shorter. The other advantage of blocking writes at the host port is that it is all managed by the storage. There is no automation or inter-LPAR communication required to get IO Consistency. Personally, I believe if you have BCM then At-Time split is the way to go. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of Bruce Black > Sent: Saturday, 18 March 2006 12:30 AM > To: [email protected] > Subject: Re: virtual copies > > > > > At Time splits with Shadowimage and/or TrueCopy use Timestamps to > initiate > > the split and create consistency. There is no blockade of writes for "a > few > > seconds" while all the volumes are split. > Ron, you are right, ShadowImage doesn't operate quite the same as IBM > FlashCopy and EMC Consistent split/snap. > > Do you know if the ShadowImage Flashcopy feature operates like the IBM > Consistent Flash, in that it does suspend I/O? > > -- > 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 ---------------------------------------------------------------------- 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
