ext3 +2TB fs

[Andreas Dilger]

On Feb 25, 2005  16:36 -0600, Alexander Lazarevich wrote:
> Feb 25 11:23:28 xxx kernel:  sda: sda1
> Feb 25 11:23:30 xxx kernel: SCSI device sda: 2927173632 512-byte hdwr
> sectors (1498713 MB)
> Feb 25 11:23:30 xxx kernel: SCSI device sda: drive cache: write back
> Feb 25 11:23:30 xxx kernel:  sda: sda1
> Feb 25 11:28:25 xxx kernel: EXT3-fs error (device sda1):
> ext3_check_descriptors: Inode table for group 5642 not in group (block
> 184811522)!
> Feb 25 11:28:25 xxx kernel: EXT3-fs: group descriptors corrupted !
> Feb 25 11:28:34 xxx kernel: EXT3-fs error (device sdb1):
> ext3_check_descriptors: Inode table for group 826 not in group (block
> 27000834)!
> Feb 25 11:28:34 xxx kernel: EXT3-fs: group descriptors corrupted !

The group descriptors are stored right at the start of the filesystem,
so if there is a 32-bit overflow it would corrupt them right away.

I would start by testing whether the large device works properly by
writing some pattern (e.g. 64-bit byte offset) to the start of each
4k block on disk, and then read them back to verify nothing has been
overwritten.

Next, create directories (you may need as many as 16k) to get one that
is in the >2TB part of the disk.  You can tell by the inode number and
the output from dumpe2fs.  If you write a file in that directory it
should allocate space at > 2TB on the disk, and debugfs "stat file" will
tell you the block layout of the file.

> On Fri, 25 Feb 2005, Alexander Lazarevich wrote:
> >I've got a 3.3TB ext3 on a FC3 64-bit system, running kernel 
> >2.6.10-1.766FC3smp. I create the partition with parted 1.6.21, and I make 
> >the fs via:
> >
> >mkfs.ext3 -m1 -b 4096 -T largefile4 /dev/sda1
> >
> >Works fine. bonnie++ running on it multiple times for days on end, no 
> >problems.
> >
> >However, I do the exact same setup on a RHEL4-AS i686 system, 32-bit, and 
> >the fs is totally hosed, get all kinds of errors with the filesystem, just 
> >trying to mount it doesn't work. Crud, I blew away the system, so I don't 
> >have the error logs, but it was an error about the group descriptors being 
> >corrupted. I ran fsck but it couldn't fix it. That kernel is 
> >2.6.9-5.0.3smp. I also compile with the CONFIG_LDB flag which enables 
> >large block device support. I'm told that should be all I have to do. But 
> >it just doesn't work. Not at all.
> >
> >Any ideas? I'm stuck running FC3 now unless I can get some quick fix from 
> >you guys.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://members.shaw.ca/adilger/             http://members.shaw.ca/golinux/

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