Hi all,
On Fri, 2006-04-21 at 17:05 -0700, Linus Torvalds wrote:
>
> On Fri, 21 Apr 2006, Jeff Garzik wrote:
>
> >
> > Agreed, though the original poster had already done a 400GB dd from
> > /dev/zero...
>
> Yes, but to a _file_ on the partition (ie he didn't overwrite any existign
> data, just the empty parts of a filesystem).
>
> I realize that it's not enough for the "re-allocate on write" behaviour,
> and for that you really _do_ need to re-write the whole disk to get all
> the broken blocks reallocated, but my argument was just that we should
> make sure to _tell_ people when they are overwriting all their old data ;)
>
I did not realize this before, and asked badblocks maintainer Theodore
if badblocks /some/file was supported (the man page says no); but of
course any filesystem can decide to re-allocate blocks for a file.
However, for large files where parts may be bad sectors, I am still
searching for a way to read, then re-write every physical sector
occupied by the file.
With the purpose to remap the bad sectors inside large MPEG files (where
I would rather have a few zeroed holes than a read error in them).
Anyone know such tooling exists? I suspect it has to use filesystem
specific IOCTL's to query for the blocks involved.
Regards,
Leon
On Saturday, 6. May 2006 17:09, Leon Woestenberg wrote:
> However, for large files where parts may be bad sectors, I am still
> searching for a way to read, then re-write every physical sector
> occupied by the file.
>
> With the purpose to remap the bad sectors inside large MPEG files (where
> I would rather have a few zeroed holes than a read error in them).
This much easier to solve in the player software:
do {
ret = read(fd, buffer, size)
if (ret > 0) {
playbuffer(buffer, ret)
} else if (ret < 0) {
switch(errno) {
case EIO:
playbuffer(allzeroesbuffer, size);
/* skip over this frame because of disk problems */
lseek(fd, size, SEEK_CUR);
/* TODO: Handle return or lseek() here */
}
}
} while(ret != 0)
> Anyone know such tooling exists? I suspect it has to use filesystem
> specific IOCTL's to query for the blocks involved.
The (somewhat) portable ioctl() FIBMAP would suffice.
That way you find out what blocks are this file is mapped to,
and could add some of these blocks to the badblock list of e2fsck.
Regards
Ingo Oeser