On 8/12/14, 9:42 AM, Eric Sandeen wrote: > On 8/12/14, 3:49 AM, Felipe Monteiro de Carvalho wrote: >> Hello, >> >> I am trying to recover a XFS partition (or series of partitions) where >> the main superblock was corrupted, and I see that there are multiple >> superblock copies. I'd like to guess the partition start and size >> also. > > so I guess you mean that the partition table was corrupted as well? > >> I see that the partition size can be calculated with sb_blocksize* sb_dblocks >> >> But what about the partition start? I think I can guess it based in >> the position of the found superblocks. >> >> Any ideas where is the code that writes to disk those backup >> superblocks? So far to me it looks like that their position is >> calculated as disk_size / 4 rounded (nearest rounding?) to a multiple >> of sb_blocksize, but having the exact code part would be better of >> course =) Or even better, a list of backup superblock positions... > > How hard have you tried looking? ;) > > In xfsprogs, you can find this if you search for "backup": > > " set allocation group superblock\n" > "\n" > " Example:\n" > "\n" > " 'sb 7' - set location to 7th allocation group superblock, set type to 'sb'\n" > "\n" > " Located in the first sector of each allocation group, the superblock\n" > " contains the base information for the filesystem.\n" > " The superblock in allocation group 0 is the primary. The copies in the\n" > " remaining allocation groups only serve as backup for filesystem recovery.\n" > " The icount/ifree/fdblocks/frextents are only updated in superblock 0.\n" > > The on-disk structure document describes the same thing: > > http://xfs.org/docs/xfsdocs-xml-dev/XFS_Filesystem_Structure//tmp/en-US/html/Allocation_Groups.html#Superblocks or the xfs(5) manpage :) -eric _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
