ghikikomori Posted February 25, 2009 Report Posted February 25, 2009 Hi, We had backed up 740GB out of 780GB when I accidentally pushed the EJECT button of our Quantum LTO-4 external SAS drive. Restrospect is asking for a NEW tape. It didn't resume as the tape was re-inserted. It says the tape has already a backup in it so it can't be used. What can i do?? Is that a normal behaviour? I mean it shouldn't just eject like this easy if it can't resume... Running Retrospect 6.1.230 on OSX 10.5.6 Any help is appreciated, i'll wit a while before quitting the process and throwing the tape to the trash... Thanks!
Lennart_T Posted February 25, 2009 Report Posted February 25, 2009 When your press eject, you force the tape to eject. Retrospect sees this as a write error and (correctly!) refuses to use the (semmingly) bad tape again. Just insert a new tape to continue. OR Start over with a Recycle backup.
rhwalker Posted February 25, 2009 Report Posted February 25, 2009 You might be able to continue to use that tape if you rebuilt (or perhaps updated) the catalog from media. Might depend on the type of error that was caused and how it was handled. Yes, a recycle would let the tape be used too, but would remove previous data on the tape. Russ
ghikikomori Posted February 25, 2009 Author Report Posted February 25, 2009 Thanks for such a fast response. In order to keep within time and budget I am trying to Repair (rebuild) the catalog from the tape. I assume I'll positively know what was backed up propperly so i car erase it from my HD. In ther words: Am I wrong if i assume that what appears as recorded on the tape is backed up right? There seems to be no verification going on during this rebuilding, so some data *might* be recorded wrong... Is there any verification I can make comparing to the files in my Hard Drive? Thanks so much again, -G
ghikikomori Posted February 25, 2009 Author Report Posted February 25, 2009 By the way, the LTO4 is brand new, it was our first backup with it (we were using DLT): The vendor told us the tapes are not Re-Writable, so I guess if it didn't work I'll have to just throw them away...
Lennart_T Posted February 25, 2009 Report Posted February 25, 2009 The vendor told us the tapes are not Re-Writable, so I guess if it didn't work I'll have to just throw them away... They sold WORM tapes to you? (Write Once, Read Many). I have never understood the reason to buy WORM tapes at all.
ghikikomori Posted February 25, 2009 Author Report Posted February 25, 2009 I didn't even know there was a tape format not re-writable, Lennart... It sounds ackward to me, to be true. The tape I'm using is the one Quantum attachs with the unit though. Put the blame on Quantum then. I guess the price difference (no idea how much it is) must be the reason, since I guess the tapes we ordered are WORM too. I agree they are crap since a backup CAN go wrong. Shall I throw the tape away or what?
rhwalker Posted February 25, 2009 Report Posted February 25, 2009 By the way, the LTO4 is brand new, it was our first backup with it (we were using DLT):The vendor told us the tapes are not Re-Writable, so I guess if it didn't work I'll have to just throw them away... NO! This is new information (WORM tapes) that you should have provided in your initial post. Retrospect is doing the right thing. Just use another tape as Retrospect is requesting, and the second tape will be made a second member to that backup set. It is possible, depending on the error that you caused, that Retrospect will allow you to append to this tape after the catalog has been rebuilt from the media. If not, then just add a second member to the backup set so that new data can be appended to that second member. Or, depending on your wishes, you could just start a new backup set on a new tape. WORM tapes will not permit a recycle or erase. I have never understood the reason to buy WORM tapes at all. Some institutions must operate under rules that do not permit overwriting of backup data for legal reasons. Russ
ghikikomori Posted February 25, 2009 Author Report Posted February 25, 2009 Aparently WORM tapes are half the price!!! Rebuilding gave back just 247GB out of the 740 I had already backed up... I thought someone accidentally pushing the Eject button was the reason but I'm not so sure about it anymore, it's not so easy... The thing is I'll just throw the tape away and wait for more tapes to come and see if it works better. From scratch. By the way it was giving a speed of 745Mb/min, which is ridiculously slow compared to what the specs were saying... Ard. 24h for backup+verification/tape... Thanks rhwalker and Lennart!
rhwalker Posted February 25, 2009 Report Posted February 25, 2009 Aparently WORM tapes are half the price!!! Well, yes. If they are only going to be written once (and verified, perhaps), then the coatings don't have to be as good because the life cycle requirements are much lower than multi-use tapes. Russ
ghikikomori Posted February 25, 2009 Author Report Posted February 25, 2009 Thanks for the explanation Russ. Does this mean the backup is less reliable? Can I backup different sessions on a WORM tape or I have to fulfill it at once? Cheers, G
rhwalker Posted February 25, 2009 Report Posted February 25, 2009 Thanks for the explanation Russ. Does this mean the backup is less reliable? Can I backup different sessions on a WORM tape or I have to fulfill it at once? Cheers, G I would expect that you can backup different sessions, just not overwrite (recycle). You would have to look at the specs for the particular tape, see how many passes it is rated for. Assuming no "backhitching", count two passes for each backup session (write, then verify). Some tapes are better than others. Myself, I've never used WORM tapes, but we never re-use tapes - archive them away when they fill up. Note, though, that the area near BOT gets more passes because the tape header gets read on insertion, then rewound, which causes more wear at BOT. Russ
CallMeDave Posted February 26, 2009 Report Posted February 26, 2009 I assume I'll positively know what was backed up propperly so i car erase it from my HD. If this is to be your only backup copy, then intentionally erasing data from your Source would be foolish.
Lennart_T Posted February 26, 2009 Report Posted February 26, 2009 Some institutions must operate under rules that do not permit overwriting of backup data for legal reasons. Thank you. I see, not a technical reason! In Sweden, the worm tapes cost almost as much as the "real" tapes. I guess the demand for worm tapes are low here.
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