tyler@tobe ~ % sudo fsck -r /dev/sdb1

fsck from util-linux 2.19.1
dosfsck 3.0.11, 24 Dec 2010, FAT32, LFN
There are differences between boot sector and its backup.
Differences: (offset:original/backup)
  0:eb/00, 1:3c/00, 2:90/00, 3:4d/00, 4:53/00, 5:44/00, 6:4f/00, 7:53/00
  , 8:35/00, 9:2e/00, 10:30/00, 12:02/00, 13:08/00, 14:20/00, 16:02/00
  , 21:f8/00, 24:3f/00, 26:ff/00, 28:44/00, 29:02/00, 32:bc/00, 33:35/00
  , 34:77/00, 36:ce/00, 37:1d/00, 44:02/00, 48:01/00, 50:06/00, 66:29/00
  , 67:61/00, 68:23/00, 69:43/00, 70:65/00, 71:53/00, 72:44/00, 73:20/00
  , 74:50/00, 75:4c/00, 76:41/00, 77:59/00, 78:45/00, 79:52/00, 80:20/00
  , 81:20/00, 82:46/00, 83:41/00, 84:54/00, 85:33/00, 86:32/00, 87:20/00
  , 88:20/00, 89:20/00, 510:55/00, 511:aa/00
1) Copy original to backup
2) Copy backup to original
3) No action
? 2
/.rockbox/eqs
  Contains a free cluster (204701). Assuming EOF.
/.rockbox/rockbox.mi4
  Contains a free cluster (204926). Assuming EOF.
/.rockbox/rockbox.mi4
  File size is 620544 bytes, cluster chain length is 81920 bytes.
  Truncating file to 81920 bytes.
/.rockbox/tagnavi.config
  Contains a free cluster (205190). Assuming EOF.
/.rockbox/tagnavi.config
  File size is 9172 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rbutil.log
  Contains a free cluster (205713). Assuming EOF.
/.rockbox/rbutil.log
  File size is 10681 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/games
  Contains a free cluster (82861). Assuming EOF.
/.rockbox/rocks/viewers/pdbox.rock
  Contains a free cluster (80657). Assuming EOF.
/.rockbox/rocks/viewers/pdbox.rock
  File size is 377552 bytes, cluster chain length is 266240 bytes.
  Truncating file to 266240 bytes.
/.rockbox/rocks/viewers/vbrfix.rock
  Contains a free cluster (80686). Assuming EOF.
/.rockbox/rocks/viewers/vbrfix.rock
  File size is 2752 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/viewers/midi.rock
  Contains a free cluster (80688). Assuming EOF.
/.rockbox/rocks/viewers/midi.rock
  File size is 19008 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/viewers/wavview.rock
  Contains a free cluster (80693). Assuming EOF.
/.rockbox/rocks/viewers/wavview.rock
  File size is 5636 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/viewers/frotz.rock
  Contains a free cluster (80695). Assuming EOF.
/.rockbox/rocks/viewers/frotz.rock
  File size is 54332 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/viewers/zxbox.rock
  Contains a free cluster (80738). Assuming EOF.
/.rockbox/rocks/viewers/zxbox.rock
  File size is 159724 bytes, cluster chain length is 102400 bytes.
  Truncating file to 102400 bytes.
/.rockbox/rocks/viewers/lua.rock
  Contains a free cluster (80782). Assuming EOF.
/.rockbox/rocks/viewers/lua.rock
  File size is 141076 bytes, cluster chain length is 77824 bytes.
  Truncating file to 77824 bytes.
/.rockbox/rocks/viewers/imageviewer.rock
  Contains a free cluster (80800). Assuming EOF.
/.rockbox/rocks/viewers/imageviewer.rock
  File size is 13156 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/viewers/mikmod.rock
  Contains a free cluster (82062). Assuming EOF.
/.rockbox/rocks/viewers/mikmod.rock
  File size is 169844 bytes, cluster chain length is 73728 bytes.
  Truncating file to 73728 bytes.
/.rockbox/rocks/viewers/lua/actions.lua
  Contains a free cluster (82858). Assuming EOF.
/.rockbox/rocks/viewers/lua/actions.lua
  File size is 6481 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/viewers/lua/buttons.lua
  Contains a free cluster (82860). Assuming EOF.
/.rockbox/rocks/viewers/lua/buttons.lua
  File size is 416 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/demos/pictureflow_emptyslide.bmp
  Contains a free cluster (204638). Assuming EOF.
/.rockbox/rocks/demos/pictureflow_emptyslide.bmp
  File size is 11078 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/rocks/demos/pictureflow.rock
  Contains a free cluster (204641). Assuming EOF.
/.rockbox/rocks/demos/pictureflow.rock
  File size is 25332 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/rocks/demos/matrix.rock
  Contains a free cluster (204698). Assuming EOF.
/.rockbox/rocks/demos/matrix.rock
  File size is 27080 bytes, cluster chain length is 20480 bytes.
  Truncating file to 20480 bytes.
/.rockbox/langs/slovenscina.lng
  Contains a free cluster (204717). Assuming EOF.
/.rockbox/langs/slovenscina.lng
  File size is 9308 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/langs/chinese-trad.lng
  Contains a free cluster (204725). Assuming EOF.
/.rockbox/langs/chinese-trad.lng
  File size is 8885 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/langs/portugues.lng
  Contains a free cluster (204728). Assuming EOF.
/.rockbox/langs/portugues.lng
  File size is 11950 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/langs/walon.lng
  Contains a free cluster (204741). Assuming EOF.
/.rockbox/langs/walon.lng
  File size is 11879 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/langs/turkce.lng
  Contains a free cluster (204746). Assuming EOF.
/.rockbox/langs/turkce.lng
  File size is 3406 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/langs/basque.lng
  Contains a free cluster (204747). Assuming EOF.
/.rockbox/langs/basque.lng
  File size is 10683 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/langs/galego.lng
  Contains a free cluster (204757). Assuming EOF.
/.rockbox/langs/galego.lng
  File size is 11883 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/langs/bulgarian.lng
  Contains a free cluster (204768). Assuming EOF.
/.rockbox/langs/bulgarian.lng
  File size is 20406 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/langs/srpski.lng
  Contains a free cluster (204780). Assuming EOF.
/.rockbox/langs/srpski.lng
  File size is 18416 bytes, cluster chain length is 16384 bytes.
  Truncating file to 16384 bytes.
/.rockbox/langs/hrvatski.lng
  Contains a free cluster (204783). Assuming EOF.
/.rockbox/langs/hrvatski.lng
  File size is 11810 bytes, cluster chain length is 8192 bytes.
  Truncating file to 8192 bytes.
/.rockbox/langs/japanese.lng
  Contains a free cluster (204794). Assuming EOF.
/.rockbox/langs/japanese.lng
  File size is 14632 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/langs/tagalog.lng
  Contains a free cluster (204803). Assuming EOF.
/.rockbox/langs/tagalog.lng
  File size is 10281 bytes, cluster chain length is 8192 bytes.
  Truncating file to 8192 bytes.
/.rockbox/langs/magyar.lng
  Contains a free cluster (204804). Assuming EOF.
/.rockbox/langs/magyar.lng
  File size is 11464 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/langs/russian.lng
  Contains a free cluster (204826). Assuming EOF.
/.rockbox/langs/russian.lng
  File size is 18654 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/langs/francais.lng
  Contains a free cluster (204843). Assuming EOF.
/.rockbox/langs/francais.lng
  File size is 12582 bytes, cluster chain length is 12288 bytes.
  Truncating file to 12288 bytes.
/.rockbox/langs/english-us.lng
  Contains a free cluster (204846). Assuming EOF.
/.rockbox/langs/english-us.lng
  File size is 9459 bytes, cluster chain length is 8192 bytes.
  Truncating file to 8192 bytes.
/.rockbox/fonts/12-Adobe-Helvetica.fnt
  Contains a free cluster (204875). Assuming EOF.
/.rockbox/fonts/12-Adobe-Helvetica.fnt
  File size is 36294 bytes, cluster chain length is 32768 bytes.
  Truncating file to 32768 bytes.
/.rockbox/fonts/minecraft.fnt
  Contains a free cluster (205758). Assuming EOF.
/.rockbox/fonts/minecraft.fnt
  File size is 26566 bytes, cluster chain length is 8192 bytes.
  Truncating file to 8192 bytes.
/.rockbox/codepages/950.cp
  Contains a free cluster (205101). Assuming EOF.
/.rockbox/codepages/950.cp
  File size is 65536 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/wps/rockbox_failsafe.fms
  Contains a free cluster (205136). Assuming EOF.
/.rockbox/wps/rockbox_failsafe.fms
  File size is 131 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/wps/minecraft.wps
  Contains a free cluster (205765). Assuming EOF.
/.rockbox/wps/minecraft.wps
  File size is 1065 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/wps/cabbiev2/wpsbackdrop-176x220x16.bmp
  Contains a free cluster (205140). Assuming EOF.
/.rockbox/wps/cabbiev2/wpsbackdrop-176x220x16.bmp
  File size is 116216 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/wps/classic_statusbar/rec_channels.bmp
  Contains a free cluster (205182). Assuming EOF.
/.rockbox/wps/classic_statusbar/rec_channels.bmp
  File size is 118 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/wps/classic_statusbar/battery.bmp
  Contains a free cluster (205184). Assuming EOF.
/.rockbox/wps/classic_statusbar/battery.bmp
  File size is 510 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/wps/minecraft/cover.bmp
  Contains a free cluster (205771). Assuming EOF.
/.rockbox/wps/minecraft/cover.bmp
  File size is 29008 bytes, cluster chain length is 8192 bytes.
  Truncating file to 8192 bytes.
/.rockbox/wps/minecraft/led-bar.bmp
  Contains a free cluster (205823). Assuming EOF.
/.rockbox/wps/minecraft/led-bar.bmp
  File size is 1062 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/wps/minecraft/fm-backdrop.bmp
  Contains a free cluster (205824). Assuming EOF.
/.rockbox/wps/minecraft/fm-backdrop.bmp
  File size is 27702 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/codecs/kss.codec
  Contains a free cluster (205207). Assuming EOF.
/.rockbox/codecs/kss.codec
  File size is 96360 bytes, cluster chain length is 49152 bytes.
  Truncating file to 49152 bytes.
/.rockbox/codecs/cook.codec
  Contains a free cluster (205250). Assuming EOF.
/.rockbox/codecs/cook.codec
  File size is 43952 bytes, cluster chain length is 8192 bytes.
  Truncating file to 8192 bytes.
/.rockbox/codecs/vorbis.codec
  Contains a free cluster (205343). Assuming EOF.
/.rockbox/codecs/vorbis.codec
  File size is 116592 bytes, cluster chain length is 86016 bytes.
  Truncating file to 86016 bytes.
/.rockbox/codecs/sgc.codec
  Contains a free cluster (205351). Assuming EOF.
/.rockbox/codecs/sgc.codec
  File size is 72312 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/codecs/tta.codec
  Contains a free cluster (205369). Assuming EOF.
/.rockbox/codecs/tta.codec
  File size is 9592 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/codecs/mod.codec
  Contains a free cluster (205373). Assuming EOF.
/.rockbox/codecs/mod.codec
  File size is 9512 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/codecs/vox.codec
  Contains a free cluster (205376). Assuming EOF.
/.rockbox/codecs/vox.codec
  File size is 6564 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/codecs/atrac3_rm.codec
  Contains a free cluster (205381). Assuming EOF.
/.rockbox/codecs/atrac3_rm.codec
  File size is 41136 bytes, cluster chain length is 16384 bytes.
  Truncating file to 16384 bytes.
/.rockbox/codecs/a52.codec
  Contains a free cluster (205395). Assuming EOF.
/.rockbox/codecs/a52.codec
  File size is 43460 bytes, cluster chain length is 28672 bytes.
  Truncating file to 28672 bytes.
/.rockbox/codecs/ape.codec
  Contains a free cluster (205402). Assuming EOF.
/.rockbox/codecs/ape.codec
  File size is 61760 bytes, cluster chain length is 12288 bytes.
  Truncating file to 12288 bytes.
/.rockbox/codecs/ay.codec
  Contains a free cluster (205427). Assuming EOF.
/.rockbox/codecs/ay.codec
  File size is 27840 bytes, cluster chain length is 12288 bytes.
  Truncating file to 12288 bytes.
/.rockbox/codecs/wmapro.codec
  Contains a free cluster (205526). Assuming EOF.
/.rockbox/codecs/wmapro.codec
  File size is 89824 bytes, cluster chain length is 65536 bytes.
  Truncating file to 65536 bytes.
/.rockbox/codecs/vgm.codec
  Contains a free cluster (205554). Assuming EOF.
/.rockbox/codecs/vgm.codec
  File size is 105576 bytes, cluster chain length is 90112 bytes.
  Truncating file to 90112 bytes.
/.rockbox/codecs/aac.codec
  Contains a free cluster (205580). Assuming EOF.
/.rockbox/codecs/aac.codec
  File size is 204464 bytes, cluster chain length is 90112 bytes.
  Truncating file to 90112 bytes.
/.rockbox/codecs/asap.codec
  Contains a free cluster (205608). Assuming EOF.
/.rockbox/codecs/asap.codec
  File size is 84944 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/codecs/speex.codec
  Contains a free cluster (205635). Assuming EOF.
/.rockbox/codecs/speex.codec
  File size is 49096 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/codecs/wavpack.codec
  Contains a free cluster (205647). Assuming EOF.
/.rockbox/codecs/wavpack.codec
  File size is 32192 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/codecs/adx.codec
  Contains a free cluster (205662). Assuming EOF.
/.rockbox/codecs/adx.codec
  File size is 10108 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
/.rockbox/codecs/wma.codec
  Contains a free cluster (205674). Assuming EOF.
/.rockbox/codecs/wma.codec
  File size is 110880 bytes, cluster chain length is 20480 bytes.
  Truncating file to 20480 bytes.
/.rockbox/docs/sample.colours
  Contains a free cluster (205703). Assuming EOF.
/.rockbox/docs/sample.colours
  File size is 82 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
/.rockbox/docs/COPYING.txt
  Contains a free cluster (205706). Assuming EOF.
/.rockbox/docs/COPYING.txt
  File size is 15127 bytes, cluster chain length is 4096 bytes.
  Truncating file to 4096 bytes.
Reclaimed 21823 unused clusters (89387008 bytes).
Free cluster summary wrong (35207 vs. really 78830)
1) Correct
2) Don't correct
? 1
Perform changes ? (y/n) y
/dev/sdb1: 989 files, 895826/974656 clusters




tyler@tobe ~ % sudo fsck -r /dev/sdb1

fsck from util-linux 2.19.1
e2fsck 1.41.14 (22-Dec-2010)
fsck.ext2: Superblock invalid, trying backup blocks...
fsck.ext2: Bad magic number in super-block while trying to open /dev/sdb1

The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>