In article <CACXMG+s-KcfMV_eFRqm12asaQ8rDABL123bD+ur8jwNVLyQXjw at mail.gmail.com>, Erick Perez - Quadrian Enterprises <eperez at quadrianweb.com> wrote: > @tonymountifield > Does this still hold true? > https://superuser.com/a/1075837 It wouldn't surprise me. What I take away from those tests is that it is indeed important to use a bs= setting that corresponds to the disk physical block size, which is why I said to use bs=4096. When I used "conv=noerror,sync bs=4096" I got an image of the correct size. That seems to correspond with what is said in the comment you linked to. Cheers Tony > On Sun, Sep 27, 2020 at 7:21 AM Tony Mountifield <tony at softins.co.uk> wrote: > > > In article <E02FA554-9D6D-4E7D-8A78-5FBDE1DE939D at kicp.uchicago.edu>, > > Valeri Galtsev <galtsev at kicp.uchicago.edu> wrote: > > > > > > > > > > On Sep 26, 2020, at 8:05 AM, Jerry Geis <jerry.geis at gmail.com> wrote: > > > > > > > > I have a disk that is flagging errors, attempting to rescue the data. > > > > > > > > I tried dd first - if gets about 117G of 320G disk and stops > > incrementing > > > > the save image any more. > > > > > > did you try > > > > > > dd conv=noerror … > > > > > > this flag makes dd not stop on input error. Whatever is irrecoverable is > > irrecoverable, but this way you will get stuff > > > beyond failure point. > > > > You need conv=noerror,sync so that unreadable sectors get replaced by > > zeros instead of not being written out at all. > > Without sync, the filesystem geometry on the destination image will be > > wrong after the first error. > > > > You also need bs=4096 so that ONLY the bad sector(s) get zeroed, and not > > the surrounding ones. If you have, say, > > bs=1M, then you will get a megabyte of zeros if any block within that > > megabyte is bad. > > > > I'm speaking from recent experience! > > > > Cheers > > Tony > > > > -- > > Tony Mountifield > > Work: tony at softins.co.uk - http://www.softins.co.uk > > Play: tony at mountifield.org - http://tony.mountifield.org > > _______________________________________________ > > CentOS mailing list > > CentOS at centos.org > > https://lists.centos.org/mailman/listinfo/centos > > > > > -- > > --------------------- > Erick Perez > Quadrian Enterprises S.A. - Panama, Republica de Panama > Skype chat: eaperezh > WhatsApp IM: +507-6675-5083 > --------------------- > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > -- Tony Mountifield Work: tony at softins.co.uk - http://www.softins.co.uk Play: tony at mountifield.org - http://tony.mountifield.org