"Richard L Peurifoy" <r-peuri...@neo.tamu.edu> wrote in message news:<4c85308b.1010...@neo.tamu.edu>... > On 9/3/2010 7:41 PM, Clark Morris wrote: > > On 3 Sep 2010 15:52:25 -0700, in bit.listserv.ibm-main you wrote: > > > >> On 9/3/2010 5:36 PM, Gerhard Adam wrote: > >>>> The way I read the articles, there was mirroring and the failure of > >>>> primary was made disastrous by the failure of the mirroring device. If > >>>> this is the case, what are the probabilities of the same thing on IBM > >>>> devices regardless of the operating system? > >>> > >>> That's probably true. After all, who would ever think to have more than one > >>> backup. > >> > >> Mirroring doesn't equal backup. > >> > >> Mirroring will happily duplicate bad data written by a misbehaving > >> program (or by misbehaving hardware for that matter). > > > > And a backup program will blithely copy bad data to the backup > > mechanism. > > Yes, but with mirroring it is already to late when the change occurs. > With a backup you have a chance to restore the bad data if you catch it > in time. We do backups every night, and keep them for at least a month. > The applications folks do their own backups as well, and may keep them
> longer. > > It is certainly possible to not realize the problem until the backup > is no longer available, but at least you have a chance. > > -- > Richard And mirroring will also happily promote a delete request to the other side. A backup will be there in case of an unintended delete. Kees. ******************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. Koninklijke Luchtvaart Maatschappij N.V. (also known as KLM Royal Dutch Airlines) is registered in Amstelveen, The Netherlands, with registered number 33014286 ******************************************************** ---------------------------------------------------------------------- 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
