On Sun, Jul 26, 2009 at 04:44:45AM +1100, leon zadorin wrote: > Man page for mount_vnd states: > " > The `c' partition of a vnd image should not be used. When a superblock > becomes damaged, fsck_ffs(8) needs information contained in the disklabel > to determine the location of alternate superblocks. This information is > not available when directly using the `c' partition, so checking the file > system image will fail. > " > > Also, the man page for newfs states: > " > Before running newfs or mount_mfs, the disk must be labeled using > disklabel(8). newfs builds a file system on the specified special de- > vice, basing its defaults on the information in the disk label. > " > > But... the man 5 disklabel states: > " > Note that when a disk has no real BSD disklabel the kernel creates a de- > fault label so that the disk can be used. > " > > And indeed, it would appear (or may be my brain is getting sleepy) > that, running newfs on a device (such as svnd0c or vnd0c) which has no > disklabel installed explicitly does work ok... > ... now -- if, as man page for mount_vnd states, fsck_ffs needs > disklabel info when superblock is damaged -- why would it have any > trouble getting the default label that kernel creates for the "disk" > automatically as per man 5 disklabel quote above (the very same info, > I presume that newfs uses when initializing the fs initially on an > image with no explicit label)? >
again, i can't help much here. but creating a disklabel for the first time might be different to using an existing disklabel. so it could be, as the man page suggests, that the alternate superblock info is gleaned after the disk is in use. i dunno. anyone else? jmc
