No, I meant rewind since John McKown had suggested: "... use of BLP to read the tape labels can be protected via the tape management system, or even with RACF now-a-days. Does not apply if you use EXCP to REW the tape ..."
However, you are correct, traversing tape marks in either direction could be cause for concern. > Date: Wed, 3 Oct 2012 16:43:16 +0200 > From: kees.verno...@klm.com > Subject: Re: How to get a tape's DSCB > To: IBM-MAIN@LISTSERV.UA.EDU > > With rewinding you mean: forward skipping? AFAIK this is prevented by > the hardware and not overrable by software. Investigating the > recoverability of overwritten data on tapes in the past, we ran into a > company that had modified the 3490 microcode to read data that existed > after the tapemark at the end of the overwriting data. > > Kees. > > "J R" <jayare...@hotmail.com> wrote in message > news:<bay145-w16b10a3a818b67b71a41da3...@phx.gbl>... > > Rather than IOS, the channel should do the checking. For DASD, the > SetFileMask command is used to prevent seeking outside of the dataset's > extents. Don't remember if there's anything similar to prevent > rewinding over tape marks. > > > > > > > Date: Wed, 3 Oct 2012 09:15:50 -0500 > > > From: john.mck...@healthmarkets.com > > > Subject: Re: How to get a tape's DSCB > > > To: IBM-MAIN@LISTSERV.UA.EDU > > > > > > It would be very difficult and have a lot of overhead to have IOS > (not iOS) check every CCW chain for "suspect" CCWs. It is given as one > of the reasons why RACF does not implement PDS member security. It's too > easy to update a PDS member via TTR without any member name anywhere in > sight. > > > > > > -- > > > John McKown > > > Systems Engineer IV > > > IT > > > > > > Administrative Services Group > > > > > > HealthMarkets(r) > > > > > > 9151 Boulevard 26 * N. Richland Hills * TX 76010 > > > (817) 255-3225 phone * > > > john.mck...@healthmarkets.com * www.HealthMarkets.com > > > > > > Confidentiality Notice: This e-mail message may contain confidential > or proprietary information. If you are not the intended recipient, > please contact the sender by reply e-mail and destroy all copies of the > original message. HealthMarkets(r) is the brand name for products > underwritten and issued by the insurance subsidiaries of HealthMarkets, > Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life > Insurance Company of TennesseeSM and The MEGA Life and Health Insurance > Company.SM > > > > > > > > > > -----Original Message----- > > > > From: IBM Mainframe Discussion List > [mailto:IBM-MAIN@LISTSERV.UA.EDU] > > > > On Behalf Of Paul Gilmartin > > > > Sent: Wednesday, October 03, 2012 9:09 AM > > > > To: IBM-MAIN@LISTSERV.UA.EDU > > > > Subject: Re: How to get a tape's DSCB > > > > > > > > On Wed, 3 Oct 2012 07:55:44 -0500, McKown, John wrote: > > > > > > > > >And, just to be complete, you are assuming that your customers > will be > > > > using IBM standard tape labels. Granted, who doesn't? But it is an > > > > assumption. Also, remember that in many shops, use of BLP to read > the > > > > tape labels can be protected via the tape management system, or > even > > > > with RACF now-a-days. Does not apply if you use EXCP to REW the > tape, > > > > of course. > > > > > > > > > Inconsistency. Either the REW CCW or EXCP itself should be > likewise > > > > RACF protected or protected by the tape management system. The > > > > unprivileged user should have no opportunity to overwrite labels > of > > > > library tapes. > > > > > > > > I suppose a virtual tape might have a virtual label, and any > attempt > > > > to invalidate the label should fail or be ineffective. > > > > > > > > -- gil > > > > > > > > > ---------------------------------------------------------------------- > > > > For IBM-MAIN subscribe / signoff / archive access instructions, > > > > send email to lists...@listserv.ua.edu with the message: INFO > IBM-MAIN > > > > > > > > > > ---------------------------------------------------------------------- > > > For IBM-MAIN subscribe / signoff / archive access instructions, > > > send email to lists...@listserv.ua.edu with the message: INFO > IBM-MAIN > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > > ******************************************************** > For information, services and offers, please visit our web site: > http://www.klm.com. 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