{ 16 comments… read them below or add one }

1 Anonymous May 31, 2006 at 5:13 pm

# dumpe2fs /dev/hda3grep -i superblock
above command is not running here |(pipe) is missing, anyway

I am getting different output as you mentioned
[root@sachan /root]# dumpe2fs /dev/hda1 | grep -i superblock
dumpe2fs 1.19, 13-Jul-2000 for EXT2 FS 0.5b, 95/08/09
[root@sachan /root]#

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2 nixcraft May 31, 2006 at 9:59 pm

Opps pipe was missing, thanks for heads up.

Hmm it should give the output.

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3 Kristian May 5, 2007 at 4:33 pm

It should be mentioned that dumpe2fs only is for the ext2/ext3 file systems.

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4 bipul August 1, 2007 at 8:14 am

Hello Unix Team
how are you

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5 Swapnil August 31, 2007 at 6:05 am

Hi Vivek,

I have a doubt as how many redundant backups of superblock are created in the file system ? Is it made on every block group or only on initial few block groups ?
In the filesystem that I created of size 128 MB with 16 block groups, when I run the dumpe2fs command on it, it gives the info on superblocks (These are not the exact wordings of the output ) :
primary superblock is present on block group 0,
back up superblock is present on block group 1, 3, 5, 7, 9.

Similarly for a file system with 256 MB size and 31 block groups, primary superblock is present on block group 0 and backups are present on block groups 1,3,5,7, and 9.

So my doubt is how does the file system how many backups of the superblock to be created ?
And the same doubt for block group descriptors as well. Block group descriptors are not present in each block group but only in the block groups where superblock is present.

Hoping for an earliest response.

Thanks,
Swapnil

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6 Sunil April 18, 2008 at 6:40 am

Hey this command id not working on my system…

[sunilv@lnx202-28 ~]$ dump2fs /u/sunilv | grep -i superblock
dump2fs: Command not found.

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7 rakesh September 13, 2011 at 7:52 am

dude.. commands is dump2efs

u used dump2fs

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8 nixCraft April 18, 2008 at 10:46 am

Use full path /sbin/dumpe2fs, you are logged in as regular user and /sbin and /usr/sbin not in PATH settings.

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9 c November 24, 2008 at 6:10 am

To Swapnil,

You have sparse_super mode so super block and backups are saved in groups 0,1,3^n,5^n,7^n (e.g. 0,1,3,5,7,9,25,27,…). If you take a look at mke2fs code, you’ll see these places where super blocks are saved.

p.s. this is a very late comment but just wanted to comment..

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10 Govindasamy C January 28, 2009 at 5:25 am

Its working fine for me
sunil i think you did not give space after the command dumpe2fs

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11 try Dope January 24, 2011 at 4:46 am

so… what the hell is Superblock, and can you please please be careful using the word/term …. “OBJECT” . You just cant use it at your whim.

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12 sox May 24, 2011 at 1:37 am

what is meant by offset information in a filesystem?

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13 saikumar July 14, 2011 at 3:59 am

is it possible to install linux in personal lappies? core2duo processor( dell laptop)…
is it possible even vmware workstation is installed in laptops….

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14 lanh May 17, 2012 at 8:06 am

Good content; I like how you explain this topic very simply, as linux is typically hard to grasp.

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15 Aravind October 3, 2012 at 7:00 am

Very fine . . . . . . .u

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16 tony September 24, 2014 at 10:01 am

Thanks, it is very well explained.

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