No assumptions. This is all experience/observations from several iterations of DR plans and differing management objectives.
In many (most?) tape solutions (to include ATL), tapes are physically ejected, manually boxed, manually transported (via PTAM), manually stored, manually retrieved, manually received and inventoried, and manually reloaded into the ATL. That's a lot of human interventions. The ATL in the DR center is not capable of mounting a tape from a shipping box. A human has to load the tapes into the ATL. True, an ATL in the DR center could be used as offsite backup. And that reduces the MTR somewhat by eliminating the PTAM step in the recovery script. But you still have to get the tape to the DR site. Since our subspace transporter is on backorder, we have to transport tapes by truck. Your point contrasting backup and replication is well taken. However, in a DR context, a 'backup' is just as critical as primary data and should be replicated. You are also correct in that I may not have used the acronyms correctly. But you got the ideas. I should also point out a new idea: networked VTS. The IBM TS7740 (and I'm sure some others) has the ability to be networked with other TS7740's to automatically replicate virtual tapes. Unlike the DASD XRC/PPRC solutions, the network pipe can be sized on average loads and be a bit smaller (less expensive). -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of R.S. Sent: Wednesday, March 24, 2010 10:22 AM To: IBM-MAIN@bama.ua.edu Subject: Re: Mainframe Executive article on the death of tape Hal Merritt pisze: > Perhaps if you look only at the media proper, but perhaps not if you look at > the TCO*. > > A tape based solution almost invariably includes many humans and physical > activities in the process. That's expansive. Darned expensive. And slow. Very > slow. Bad assumptions. No human interventions are necessary. Have you seen about ATL? Autmated Tape Library? > Worse, in a DR scenario physical tapes are S-L-O-W because they have to be > transported via PTAM* from the storage site to the DR site. This can push a > MTR* out to a couple of days. Again, BAD ASSUMPTION. No need to PTAM. ATL can reside in DR datacentre. The second one. Forgive me malice: how fast are non-tape media when transported via PTAM? Are the disk any faster during transportation? > These days, one can link a couple of DS8100's and have critical data > redundancy for a very competitive TCO. Depending on your specific situation, > you could set a realistic MTR objective of an hour or so. Don't confuse backup and replication. Even three-site solution does not protect you form human or application error. Mistakenly deleted dataset is deleted in both primary and secondary site. PiT copy is the solution but quite expensive for medium and large amounts of data. > *TCO = Total Cost of Ownership. The total bottom line dollars > involved. > *PTAM = Pickup Truck Access Method. Physically moving a tape cartridge > from site A to site B. (From an IBM Redbook on the subject.) > *MTR = Mean Time to Recovery. The total clock time from the point > where normal processing ends to the point where normal processing > resumes as if nothing happened. MTR usually means time to REPAIR. Your descriptions regards RTO - Recovery Time Objective (Recovery Point Objective, Recovery Time Objective - crucial parameters for any DR and backup plans). Of course this is acronym, and by definition can be overloaded (have different meanings). I presented popular ones in this context. -- Radoslaw Skorupka Lodz, Poland -- BRE Bank SA ul. Senatorska 18 00-950 Warszawa www.brebank.pl Sd Rejonowy dla m. st. Warszawy XII Wydzia Gospodarczy Krajowego Rejestru Sdowego, nr rejestru przedsibiorców KRS 0000025237 NIP: 526-021-50-88 Wedug stanu na dzie 01.01.2009 r. kapita zakadowy BRE Banku SA (w caoci wpacony) wynosi 118.763.528 zotych. W zwizku z realizacj warunkowego podwyszenia kapitau zakadowego, na podstawie uchway XXI WZ z dnia 16 marca 2008r., oraz uchway XVI NWZ z dnia 27 padziernika 2008r., moe ulec podwyszeniu do kwoty 123.763.528 z. Akcje w podwyszonym kapitale zakadowym BRE Banku SA bd w caoci opacone. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html NOTICE: This electronic mail message and any files transmitted with it are intended exclusively for the individual or entity to which it is addressed. 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