Subject: Re: checking integrity of already written CD/DVD - msg#00667

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Re: [OT] To synchronize system time witn NTP-server with no winter time shift whole year - how to?

On Tuesday 31 March 2009 00:39:46 Mike Bird wrote: > On Mon March 30 2009 16:12:57 Tom Furie wrote: > > On Mon, Mar 30, 2009 at 04:47:38PM -0600, Paul E Condon wrote: > > > Now, I want to stop arguing about the descriptions. But just one last > > > shot. I believe it is factually incorrect to say that you 'lose an > > > hour' in switching from standard to summer time. It is conventional > > > wording, it is manifestly untrue. But if people say it often enough, > > > it becomes something that is used in syllogisms as if it were a fact. > > > > To be slightly pedantic about it, if you go to bed at whatever your > > usual time is before the clocks change and still have to get up at the > > same (clock) time in the morning as you did the day before, then you do > > lose an hour of sleep, that night. Then again, by the same argument, > > seven months or so later you get that hour back, so it all balances > > anyway. To be unpedantic and factual, what officially happens here in the UK is that we lose an hour of clock time. The clock hour between 01:00 and 02:00 does not exist that night. Clocks are deemed to move from 00:00:59 to 02:00. When we move the other way we gain an hour of clock time. Clocks move from 01:59:59 to 01:00:00. Lisi -- To UNSUBSCRIBE, email to debian-user-REQUEST@xxxxxxxxxxxxxxxx with a subject of "unsubscribe". Trouble? Contact listmaster@xxxxxxxxxxxxxxxx

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Re: checking integrity of already written CD/DVD

> On 29.03.09 16:27, Boyd Stephen Smith Jr. wrote: > > Not in my experience. Both DVDs and CDs have a physical sector size. If > > the image is not a multiple of that sector size, the md5sum of the block > > device and the image will differ, because of the extra bits in the last > > physical sector. On 31.03.09 09:53, Matus UHLAR - fantomas wrote: > afaik, if the same image is written to multiple CDs/DVDs, they all should > have the same md5sum, independently on its size. That is the one md5sum > shjould report. The same for sha1sum. ... could this problem come out of fact that there was something different burned on those medias before? -- Matus UHLAR - fantomas, uhlar@xxxxxxxxxxx ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. A day without sunshine is like, night. -- To UNSUBSCRIBE, email to debian-user-REQUEST@xxxxxxxxxxxxxxxx with a subject of "unsubscribe". Trouble? Contact listmaster@xxxxxxxxxxxxxxxx

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Re: checking integrity of already written CD/DVD

On 2009-03-29_16:27:56, Boyd Stephen Smith Jr. wrote: > In <20090329202842.GA3540@xxxxxxxxxxxxx>, Andrei Popescu wrote: > >On Sun,29.Mar.09, 20:28:44, Angelin Lalev wrote: > >> Is there a way to check a written DVD against the checksum of the iso > >> image written on it? > >$ md5sum /dev/dvd > > > >This should result in *exactly* the same checksum as the iso > > Not in my experience. Both DVDs and CDs have a physical sector size. If the > image is not a multiple of that sector size, the md5sum of the block device > and the image will differ, because of the extra bits in the last physical > sector. > > head -c $(wc -c image) /dev/dvd | md5sum > should be the same as > md5sum image > though. This doesn't work for me, but something similar does. Don't know why my system behaves as it does. Here is my situation: I have two CD/DVD drives hdc and hdd. hdc is read only, hdd also is a burner. I burn an iso on hdd and read it back using dd. I always get a read back that is 5 to 10 ik blocks shorter than the iso file that I burned from. I put the newly burnt CD into hdc and read with dd, and I alway get a read back the is 5 to 10 1k block longer that the original iso file. As you might expect, the exact command given above never works for me on either drive but ... I can read back on drive hdc using dd into a file on disk, call it cd.iso I then use dd to copy cd.iso to cd2.iso and specify a block count that is equal to that of the original iso from which the CD was burnt. The MD5SUM of cd2.iso invariably agrees with the MD5SUM of the original iso. It seems to me this is something wrong in Linux, the kernel, and ought to be fixable. In the past it did work without all the fussiness, but not since Etch, or maybe Sarge. And it is hardware dependent. It should be possible to automate with a script, but I haven't tried. I only burn CDs when Debian issues a new release, so its not high on my to-do list. -- Paul E Condon pecondon@xxxxxxxxxxxxxxxx -- To UNSUBSCRIBE, email to debian-user-REQUEST@xxxxxxxxxxxxxxxx with a subject of "unsubscribe". Trouble? Contact listmaster@xxxxxxxxxxxxxxxx

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Re: checking integrity of already written CD/DVD

> On 29.03.09 16:27, Boyd Stephen Smith Jr. wrote: > > Not in my experience. Both DVDs and CDs have a physical sector size. If > > the image is not a multiple of that sector size, the md5sum of the block > > device and the image will differ, because of the extra bits in the last > > physical sector. On 31.03.09 09:53, Matus UHLAR - fantomas wrote: > afaik, if the same image is written to multiple CDs/DVDs, they all should > have the same md5sum, independently on its size. That is the one md5sum > shjould report. The same for sha1sum. ... could this problem come out of fact that there was something different burned on those medias before? -- Matus UHLAR - fantomas, uhlar@xxxxxxxxxxx ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. A day without sunshine is like, night. -- To UNSUBSCRIBE, email to debian-user-REQUEST@xxxxxxxxxxxxxxxx with a subject of "unsubscribe". Trouble? Contact listmaster@xxxxxxxxxxxxxxxx