Date: Sun, 1 Dec 2019 17:50:53 +0100 From: "Dr. Nikolaus Klepp" <dr.klepp@gmx.at> To: freebsd-usb@freebsd.org Subject: Re: pendrive clone impossible ? Message-ID: <201912011750.53770.dr.klepp@gmx.at> In-Reply-To: <CAFYkXj=imTgDWWkttkgtPpwTFJ4zZ10mjGcQwZ99DLTVnJGROQ@mail.gmail.com> References: <201912010728.xB17SQkC019214@sdf.org> <CAFYkXj=imTgDWWkttkgtPpwTFJ4zZ10mjGcQwZ99DLTVnJGROQ@mail.gmail.com>
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Anno domini 2019 Sun, 1 Dec 17:45:17 +0100 Tomasz CEDRO scripsit: > On Sun, Dec 1, 2019 at 8:28 AM Scott Bennett <bennett@sdf.org> wrote: > > >Does GEOM in any way prevents me from using disk that has corrupt MBR? > > Yes, most likely. > > > > >Why I cannot write a MBR from a file but I can from a md0? > > >Any hints welcome :-) > > See the last line of your messages below. > > (..) > > >ugen0.8: <Kingston DataTraveler 3.0> at usbus0 > > >umass1 on uhub0 > > >umass1: <Kingston DataTraveler 3.0, class 0/0, rev 3.20/1.10, addr 7> on usbus0 > > >umass1: SCSI over Bulk-Only; quirks = 0x8100 > > >umass1:3:1: Attached to scbus3 > > >da1 at umass-sim1 bus 1 scbus3 target 0 lun 0 > > >da1: <Kingston DataTraveler 3.0 PMAP> Removable Direct Access SPC-4 SCSI device > > >da1: Serial Number BLAHBLAH > > >da1: 400.000MB/s transfers > > >da1: 118272MB (242221056 512 byte sectors) > > >da1: quirks=0x2<NO_6_BYTE> > > >GEOM_PART: integrity check failed (da1, MBR) > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ There is your hint, courtesy of > > ||||||||| |||||||||||||||||||||| FreeBSD's GEOM_PART kernel class. > > Hello Scott and thank you for your valuable input. If you are sure > that this is NOT a problem of a pendrive or anything USB related with > that particular pendrive (i.e. some quirk required for valid > operations), and you ARE sure that this is a matter of GEOM, then: > > 1. OS / GEOM is hiding things from operator. It does not write bytes > as instructed to fix the disk, instead, it considers disk invalid and > silently discards _only_some_of_the_data_ with no clear error/warning > indication. Unacceptable!!! > > 2. OS / GEOM lies to operator. It does return a SUCCESS code while > _some_ data goes to /dev/null. Unacceptale!!! > > 3. If disk is _considered_ broken then access should be _fully_ > blocked. But how am I supposed to fix it when OS silently blocks > essential part of the fix? Who allows writing over a corrupted disk > anyway? > > 4. OS / GEOM is broken and incoherent in this area and proves system > unreliable / not trustworthy. This needs to be fixed please. Will > report a bug. > > > That "irrelevant blather" just proves above. OS cannot silently > interfere with operator actions and do whatever it likes. Other people > also noticed this problem. This is not the FreeBSD way, looks more > like Linux way. > > Now it looks like the factory pre-format pendrive was considered > invalid by GEOM, this is why the initial `dd if=/dev/da0 of=/dev/da1` > copied _almost_ whole data but without MBR. Then the situation > escalated - MBR dumped to a file could not be written to a target > drive, but it could be written from a md0 device, and all sorts of > black magic. It THIS IS UNACCEPTABLE!!! > > When I DD something from IF then it must get untouched into OF, unless > missing privilege or hardware failure error is clearly reported > preventing further actions. > > Damn, the DD is the simplest thing in Unix. > > Either I get the command executed exactly as instructed, or not > executed at all. The return code is here to say what happened. Error > is here to show me something is wrong. As simple as that. > > Now it looks like the disk is okay, just GEOM did some interpretation, > knew better what I want to, and did, without telling me that. > > Imagine there were some really sensitive backups on the drive and > system decided only to copy selected parts of them with no error. Not > a problem for you? > > Tomek > IMO your pendrive is broken. Please try the same operation on a live-linux and check again. Nik -- Please do not email me anything that you are not comfortable also sharing with the NSA, CIA ...
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