Re: logical log tape reuse

In article <332edaf3.684639814@news.netline.net>, allenj@ndr.com (Allen Jantzen) wrote: > >OK, so I am backing up logical logs (ontape -c) to dat device 1 > >Then, while this ontape -c process is still running, I do a full >archive (ontape -s -L 0) to dat device 2. > >Question: When the full archive is done, does dat device 1 >rewind to the beginning of tape, since all the logical logs already >there are now unneeded? Or does it just keep on going, oblivious to >the full archive? Merrily on, oblivious! (but see below) > >Or, more succinctly: When backing up logical logs to dat, do you just >keep sticking new tapes in as they are needed and labeling them so >that, in a restore, you know which ones to provide (based on log >numbers)?? > >Or, do the tapes holding logical logs somehow get reused as subsequent >full archives to the archive tapes make them obsolete? This second >scenario obviously seems more likely, but how does it happen??? Think of 'tar' when you think of ontape. A tape gets reused when YOU decide to do it. i.e say I started an ontape -c, backed up 3 logs, then interrupted the process. If I restart ontape -c on the same tape, the old logs are overwritten. Note, however, that a just completed full archive does not mean that the logs previously backed up are unneeded. You may need them in at least 2 cases 1. Your latest 'full archive' tape gets corrupted. In that case, you can use the L 0 archive previous to that and roll forward all the logs since then (you will be prompted tape by tape) to get to CURRENT. (I've actually tried this on a small instance) 2. Audit of who did what, when. >In addition, when using a single dat device to back up _both_ archives >and logical logs: >When I do a full archive (ontape -s -L 0), and assuming that logical >logs won't need to be backed up during the full archive, am I to eject >the logical log tape and replace it with the archive tape, all while >ontape -c is still running?? Should I stop ontape -c with a CTRL-C??? My dat device (DEC-UNIX v3.2C with OL 7.20UC4) hung when I tried something similar. I get the impression that ontape -c 'locks' the device whether it is actually writing to the tape or not. HTH. ----------------- Rudy Fernandes GIC, Kuwait -----------------