On Sun, May 27, 2012 at 8:06 PM, Arun Khan <[email protected]> wrote: > Using 'dd' to make a backup of an openwrt image (that has been > installed and configured) on a 64MB CF card > > # dd if=/dev/sdb of=openwrt.10.03.1_alix_installation.backup.img bs=4K > dd: reading `/dev/sdb': Input/output error > <<<<< this line says I/O error! > 15648+0 records in > 15648+0 records out > 64094208 bytes (64 MB) copied, 68.722 s, 933 kB/s > > but the copy is done but with return code = 1 > > # ls -l openwrt.10.03.1_alix_installation.backup.img > -rw-r--r-- 1 root root 64094208 May 27 16:49 > openwrt.10.03.1_alix_installation.backup.img > > This shows it indeed copied over 64MB into the backup image file. > > # file -s openwrt.10.03.1_alix_installation.backup.img > openwrt.10.03.1_alix_installation.backup.img: x86 boot sector; GRand > Unified Bootloader, stage1 version 0x3, stage2 address 0x2000, stage2 > segment 0x200; partition 1: ID=0x83, active, starthead 1, startsector > 63, 28609 sectors; partition 2: ID=0x83, starthead 7, startsector > 28672, 96513 sectors, code offset 0x48 > > This shows that indeed the file is a hard disk image with two > partitions in it with GRUB as the boot loader. > > # fdisk -l openwrt.10.03.1_alix_installation.backup.img > > Disk openwrt.10.03.1_alix_installation.backup.img: 64 MB, 64094208 bytes > 255 heads, 63 sectors/track, 7 cylinders, total 125184 sectors > Units = sectors of 1 * 512 = 512 bytes > Sector size (logical/physical): 512 bytes / 512 bytes > I/O size (minimum/optimal): 512 bytes / 512 bytes > Disk identifier: 0x00074710 > > Device Boot Start > End Blocks Id System > openwrt.10.03.1_alix_installation.backup.img1 * 63 > 28671 14304+ 83 Linux > openwrt.10.03.1_alix_installation.backup.img2 28672 > 125184 48256+ 83 Linux > > fdisk also recognizes the file as a hard disk image with two partitions. > > If there were i/o errors with the CF card then I think there would > have been errors reported by the above tools. > > Any hypothesis for this anamoly? > > -- > Arun Khan > _______________________________________________ > ILUGC Mailing List: > http://www.ae.iitm.ac.in/mailman/listinfo/ilugc
Try to mount it as loop device and check. If not try /dev/sdb1 (partition instead of full disk). I am not sure of what is going wrong. But just giving this a try should not do any harm. _______________________________________________ ILUGC Mailing List: http://www.ae.iitm.ac.in/mailman/listinfo/ilugc
