Scott, OK, so in this context you mean tape drives connected by FICON channel Extenders. In that case I disagree with your point in that paragraph. It is incorrect to say that Remote Tape " normally has lower bandwidth costs than remote disk."
Writing the same file to remote tape or remote disk will use the same bandwidth. Do you have some information that says otherwise? Whether we compare remote tape and disk, or replicated tape and disk the bandwidth required is the same for duplication of the same data. For MTTR comparing Remote Disk and tape, one advantage of Remote Disk is that there are strategies where there is no need to restore. The backup datasets are in native DSORG and your applications just allocate them and go. There is no restore time. For strategies that use DFDSS or similar files that require a restore, we are talking about Disk Subsystems that can read in excess of 9.5GB/sec or 370K IOPS on FICON, depending on your blocksize and configuration - and not with virtualized SATA Disks. With HyperPAV allowing a high level of parallelism on Disk I'm just not sure that tape subsystems are in the same performance league as disk given that real or emulated tape IO is single threaded, the disk arrays front-ending virtual tape are usually not high end specs, and there will some amount of data that encounters staging delays in some Virtual Tape systems. (I still have nightmares about the original IBM ATL replication performance, but I'm sure it has improved). I'll agree that MTTR from Remote Disk or Tape may not be valuable to some sites, YMMV, but Remote Disk strategies can have a significantly better MTTR than Remote or Replicated Tape, but not as good as replicated disk. This faster MTTR may be valuable to some sites. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of > Scott Rowe > Sent: Wednesday, March 24, 2010 2:30 PM > To: IBM-MAIN@bama.ua.edu > Subject: Re: [IBM-MAIN] Mainframe Executive article on the death of tape > > I don't know why you used "replication" in there, but there is quite > definitely remote tape in use. > > >>> Ron Hawkins <ron.hawkins1...@sbcglobal.net> 3/24/2010 5:24 PM >>> > Scott, > > Actually these implementations are remote disk, with some "HSM in a can" that > may or may not age-out the data to tape at a later time. I don't think there > is any true Remote Tape replication in the z/OS marketplace. > > YMMV, but there are shops that are finding a better TCO using commodity priced > rack and stack systems to do this, either through appliances, virtualized > DASD, or both. > > > > > Radoslaw was talking about remote tape. Some sites have a remote tape > > library that they can backup into, this eliminates almost all tape > > handling, and normally has lower bandwidth costs than remote disk. > > > > Ron > > ---------------------------------------------------------------------- > 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 > > > > CONFIDENTIALITY/EMAIL NOTICE: The material in this transmission contains > confidential and privileged information intended only for the addressee. If > you are not the intended recipient, please be advised that you have received > this material in error and that any forwarding, copying, printing, > distribution, use or disclosure of the material is strictly prohibited. If > you have received this material in error, please (i) do not read it, (ii) > reply to the sender that you received the message in error, and (iii) erase or > destroy the material. Emails are not secure and can be intercepted, amended, > lost or destroyed, or contain viruses. You are deemed to have accepted these > risks if you communicate with us by email. Thank you. > > > ---------------------------------------------------------------------- > 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 ---------------------------------------------------------------------- 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
