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Groups > linux.debian.user > #263156
| From | David Christensen <dpchrist@holgerdanske.com> |
|---|---|
| Newsgroups | linux.debian.user |
| Subject | Re: How to use dmsetuup? |
| Date | 2023-11-05 21:20 +0100 |
| Message-ID | <HwRLb-3nfd-3@gated-at.bofh.it> (permalink) |
| References | <Hwypb-3aI2-3@gated-at.bofh.it> <HwGmJ-3g1t-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 11/5/23 01:04, Thomas Schmitt wrote: > David Christensen wrote: >> I have been burning archive DVD-R discs for ~14 years and storing them in a >> drawer (e.g. darkness). I checked the oldest just now and it reads okay. > > That's my experience too. Okay. > I check by MD5 which are stored on the medium > together with the data. If a medium turns out unreadable then in nearly > all cases directly after burning. Adding checksum file(s) to the contents burned to disc is an important step that should not be omitted -- checksum files are a simple and direct way to validate the integrity of disc contents. Without checksum files, a computer with working applications is required to read and validate the specific file format(s). I suspect tar(1), gzip(1) and ccrypt(1) do this (?), but you are lost with plain text files. > Lesson learnt: Never overwrite the two youngest backups. I try to use the term "backup" to mean a data copying process whereby older data is overwritten by newer data. I try to use the term "archive' to mean a data copying process whereby the copy is never modified or erased. >> I have heard of CD discs disintegrating if the lacquer is scratched: >> https://en.wikipedia.org/wiki/Disc_rot > > This never hit me. But i keep my media away from high moisture, corroding > chemicals, and abrasive substances. I expect CD disc rot occurs when discs are accidentally scratched or when discs are treated badly (e.g. stored loose; not in a case). >> I have heard that RW media has a shorter lifespan than R media. > > Not to my experience. I have 4x CD-RW from 2002 (*), DVD+RW from 2004, and > BD-RE from 2008 which still work for backups. Okay. > From time to time a medium > dies during writing. This seems not to be closely related to age, though. > > (*) I have older 2x CD-RW, but no burner any more which would accept them. > They can be still read. The DVD+-RW in my primary workstation started producing intermittent write failures a few months ago. This quickly progressed to consistent write failures and consistent read failures. I cleaned the lens today, and now it reads okay. I will find out if it writes okay the next time I burn a disc. >> Does anyone have experience with M-Disc media? > > Only by reports of libburn users which say that M-Disc works like the > other media. Their durability can hardly be evaluated, given that normal > media seem to last for more than 2 decades without much problem. Okay. > I think the better alternative for archived data would be to make several > identical copies and to checkread them in intervals of a few years. As > soon as one of the copies shows problems, make new copies of the healthy > ones. Payload checksums on the medium give extra trust, The optical media could be a single point of failure. If I remove two DVD-R discs from the same case this month, burn them with identical contents, verify the checksums, store one disc locally, store the other disc off-site, and verify checksums once per year in the future, I could find that both discs fail in the same year. So, I both burn my monthly archive encrypted tarballs to DVD-R and I keep the original on RAID, which is included in my backup process. > although i only > once in my life watched a DVD giving bad data without an SCSI error. > That was reproducible with only a single drive. All others either read > the affected 32 KiB chunk correctly or threw error. Having more than one > drive helps a lot when the read quality is on the edge. Interesting. My WAG is that there was a marginal/ ambiguous dot on disc (?). > A sincere rescue effort would look like: > > xorriso -outdev /dev/sr0 \ > -check_media use=outdev \ > what=disc \ > time_limit=7200 \ > data_to="$HOME"/sr0.image \ > sector_map="$HOME"/sr0.sector_map \ > -- > > After 7200 seconds the attempt will end even if not finished. > If you want to abort earlier, do not press Ctrl+C but rather do > touch /var/opt/xorriso/do_abort_check_media > > The disc image will emerge as file "$HOME"/sr0.image . > The file "$HOME"/sr0.sector_map will record which blocks could be read > without SCSI error. If the run is repeated, then only the missing blocks > will be attempted to be read. > One may repeat with the same drive or better with different ones. > The file "$HOME"/sr0.image and "$HOME"/sr0.sector_map may be carried to > other computers to continue the rescue attempt with their drives. > If there are other partly damaged identical copies of the archive medium, > then one may use them too with the same sr0.image and sr0.sector_map > files. > > If the image is an ISO 9660 filesystem made by xorriso with option > -for_backup and thus contains MD5s, then one may check the resulting > image by: > > xorriso -for_backup -indev "$HOME"/sr0.image -check_media -- > > Any protest would indicate that the rescue attempt was not successful. > If the direcory tree is undamaged, one may check the data files by > > xorriso -for_backup -indev "$HOME"/sr0.image -check_md5_r sorry / -- > > to get the paths of files with damaged content. > > Other than with most rescue tools, the read operations of xorriso on an > optical drive will be done by direct SCSI commands, not by the Linux block > layer. This has the advantage that error messages are more specific than > just "i/o error" and that no inappropriate reading ahead will happen. Such > reading ahead causes the old TAO CD bug of Linux which gave birth to > interesting urban legends about a "fuzzy end" of data CDs. xorriso(1) is a killer app. :-) I seem to recall a post by you that indicated *BSD lacked the features needed for good optical drive/ media/ format support. Has this improved? Can I get xorriso(1) on FreeBSD? David
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How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-03 17:30 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-03 17:50 +0100
Re: How to use dmsetuup? Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-03 18:10 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-03 22:50 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-04 01:00 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-04 01:50 +0100
Re: How to use dmsetuup? "Andrew M.A. Cater" <amacater@einval.com> - 2023-11-03 23:20 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-04 01:10 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-04 12:50 +0100
Re: How to use dmsetuup? <tomas@tuxteam.de> - 2023-11-04 14:50 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-04 18:30 +0100
Re: How to use dmsetuup? tomas@tuxteam.de - 2023-11-04 19:40 +0100
Re: How to use dmsetuup? debian-user@howorth.org.uk - 2023-11-04 21:50 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-04 22:40 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-04 23:30 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-05 00:40 +0100
Re: How to use dmsetuup? yxcv@vienna.at - 2023-11-05 01:10 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-05 02:00 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-05 04:20 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-05 05:10 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-05 07:50 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-05 10:50 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-05 11:30 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-05 16:30 +0100
Re: How to use dmsetuup? "Thomas Schmitt" <scdbackup@gmx.net> - 2023-11-05 09:10 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-05 21:20 +0100
Re: How to use dmsetuup? debian-user@howorth.org.uk - 2023-11-05 21:50 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-05 23:30 +0100
Re: How to use dmsetuup? "Thomas Schmitt" <scdbackup@gmx.net> - 2023-11-05 23:20 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-05 23:50 +0100
Re: How to use dmsetuup? "Thomas Schmitt" <scdbackup@gmx.net> - 2023-11-06 08:40 +0100
xorriso and SIGTERM/SIGINT handler (was: Re: How to use dmsetuup?) Max Nikulin <manikulin@gmail.com> - 2023-11-06 05:30 +0100
Re: xorriso and SIGTERM/SIGINT handler "Thomas Schmitt" <scdbackup@gmx.net> - 2023-11-06 09:00 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-04 23:10 +0100
Re: How to use dmsetuup? Andy Smith <andy@strugglers.net> - 2023-11-04 10:40 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-04 13:30 +0100
Re: How to use dmsetuup? Franco Martelli <martellif67@gmail.com> - 2023-11-06 16:50 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-06 17:30 +0100
Re: How to use dmsetuup? Tom Dial <tddial@comcast.net> - 2023-11-08 00:50 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-08 01:30 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-08 06:10 +0100
Re: How to use dmsetuup? <tomas@tuxteam.de> - 2023-11-08 06:40 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-08 11:30 +0100
Re: How to use dmsetuup? "Andrew M.A. Cater" <amacater@einval.com> - 2023-11-08 19:10 +0100
Re: How to use dmsetuup? jeremy ardley <jeremy.ardley@gmail.com> - 2023-11-08 23:00 +0100
Re: How to use dmsetuup? Tom Dial <tddial@comcast.net> - 2023-11-09 02:10 +0100
Re: How to use dmsetuup? David Christensen <dpchrist@holgerdanske.com> - 2023-11-11 01:50 +0100
Re: How to use dmsetuup? gene heskett <gheskett@shentel.net> - 2023-11-11 04:30 +0100
Hardware for a back up server? [WAS Re: How to use dmsetuup?] "Andrew M.A. Cater" <amacater@einval.com> - 2023-11-11 18:00 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-11 18:10 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Pocket <pocket@columbus.rr.com> - 2023-11-11 18:40 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-11 19:50 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Pocket <pocket@columbus.rr.com> - 2023-11-11 21:50 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] gene heskett <gheskett@shentel.net> - 2023-11-11 22:40 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Jeffrey Walton <noloader@gmail.com> - 2023-11-11 22:10 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Jeffrey Walton <noloader@gmail.com> - 2023-11-12 00:30 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Dan Ritter <dsr@randomstring.org> - 2023-11-12 00:40 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] fxkl47BF@protonmail.com - 2023-11-11 18:30 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] David Christensen <dpchrist@holgerdanske.com> - 2023-11-12 01:10 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-12 05:40 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2023-11-13 11:40 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-13 14:00 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Andy Smith <andy@strugglers.net> - 2023-11-12 14:20 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] David Christensen <dpchrist@holgerdanske.com> - 2023-11-12 19:40 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] "Andrew M.A. Cater" <amacater@einval.com> - 2023-11-12 18:20 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] David Christensen <dpchrist@holgerdanske.com> - 2023-11-12 20:30 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-12 21:20 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] <tomas@tuxteam.de> - 2023-11-13 06:40 +0100
Linux supprt (was: Hardware for a back up server? [WAS Re: How to use dmsetuup?]) Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-13 13:50 +0100
Re: Linux supprt (was: Hardware for a back up server? [WAS Re: How to use dmsetuup?]) Larry Martell <larry.martell@gmail.com> - 2023-11-13 16:00 +0100
Re: Linux supprt Stefan Monnier <monnier@iro.umontreal.ca> - 2023-11-13 16:40 +0100
Re: Linux supprt Nicholas Geovanis <nickgeovanis@gmail.com> - 2023-11-13 22:50 +0100
Re: Linux supprt John Hasler <john@sugarbit.com> - 2023-11-13 19:00 +0100
Re: Linux supprt <tomas@tuxteam.de> - 2023-11-13 19:40 +0100
Re: Linux supprt Nicholas Geovanis <nickgeovanis@gmail.com> - 2023-11-14 18:40 +0100
Re: Linux supprt <tomas@tuxteam.de> - 2023-11-14 18:50 +0100
Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?] Joe <joe@jretrading.com> - 2023-11-13 15:10 +0100
Re: How to use dmsetuup? Tom Dial <tddial@comcast.net> - 2023-11-09 01:50 +0100
Re: How to use dmsetuup? Andy Smith <andy@strugglers.net> - 2023-11-09 16:20 +0100
Re: How to use dmsetuup? debian-user@howorth.org.uk - 2023-11-09 17:50 +0100
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