[ILUG] HOWTO recover a borked 3ware RAID-1 array (long)

[Ronan Cunniffe]

Pádraig Brady wrote:
> minor optimisation to not have temp files and break out early:
>
> for i in `seq 0 2048`; do
>     sudo dd if=/dev/sda bs=512 skip=$i count=1 2>/dev/null |
>     file - |
>     grep -q boot &&
>     echo sector $i &&
>     break
> done
>   
Yep, better.  Of course the 2048 was just me throwing a big net -  it 
happened to be big enough.
> Would my lomount.sh script help?
> http://www.pixelbeat.org/scripts/lomount.sh
>
> ./lomount.sh /dev/loop0 2 /mnt/data
>   
Yes it would.  A lot.  Now, why isn't this in my distribution?

I split the losetup and mount because it's 'losetup -o <offset>', and I 
was thinking ''mount -o o <offset>'?  naaaah...'

(For those who didn't read Pádraig's script, you can use 'mount -o 
offset=<offset>'.  Now go and read Pádraig's script.)

Anyway, on the subject of loopback, and seeing as it's still near enough 
Halloween, how about the following little code snippet:

    #define SIZE(a) (sizeof(a)/sizeof(a[0]))

    char *loop_formats[] = { "/dev/loop%d", "/dev/loop/%d" };

    for (j = 0; j < SIZE(loop_formats); j++) {

    }

What kind of nutter..... ?  Yes! Yes! We Must Compute Everything At 
Compile Time! No! *Before* Compile Time!

For anybody who wants a real fright, download the util-linux source, and 
have a look at mount/lomount.c (from which the above comes).  The 64bit 
vs 32bit goodness.  The gotos.  The stupefying option handling that 
provably shouldn't even compile.  The #ifdefs depending on why you're in 
the file.  This crap is in your /bin/mount, people....

Actually, if you want real horror, have a look at one of the old 2.11 
versions.

:-)

Ronan