Bad Super Block: Magic Number Wrong

I had a power outage a day ago and when the power came back on my FreeBSD 4.6 webserver had problems. It said it was unable to mount /var and made me start in single user mode and said to run fsck MANUALY. So i did and this is now what i get.

www# fsck /dev/ad0s1e
** /dev/ad0s1e
BAD SUPER BLOCK: MAGIC NUMBER WRONG
/dev/ad0s1e: INCOMPLETE LABEL: type 4.2BSD fsize 16384, frag 0, cpg 64, size 39102273

So i did some research and found a few places that told we me to fix the Super Block with the alternative super block. So i ran this.

www# newfs -N /dev/ad0s1e
Warning: Block size and bytes per inode restrict cylinders per group to 385.
Warning: 2240 sector(s) in last cylinder unallocated
/dev/ad0s1e: 39102272 sectors in 9547 cylinders of 1 tracks, 4096 sectors
19092.9MB in 25 cyl groups (385 c/g, 770.00MB/g, 12288 i/g)
super-block backups (for fsck -b #) at:
32, 1576992, 3153952, 4730912, 6307872, 7884832, 9461792, 11038752, 12615712, 14192672, 15769632, 17346592, 18923552, 20500512, 22077472, 23654432, 25231392, 26808352, 28385312,
29962272, 31539232, 33116192, 34693152, 36270112, 37847072

Once I found the alternative blocks I tried this.

www# fsck -b 34693152 /dev/ad0s1e
Alternate super block location: 34693152
** /dev/ad0s1e
BAD SUPER BLOCK: MAGIC NUMBER WRONG

Running FreeBSD 4.6 on PIII 450
The System has 2 drives
Root is at /dev/da0 a 4.3 GB SCSI drive
And I am missing my /var that was on a 20GB IDE drive /dev/ad0

So I still can not fix or mount the /dev/ad0s1e drive. How do I fix BAD SUPER BLOCK: MAGIC NUMBER WRONG and mount the drive?
how can I fix INCOMPLETE LABEL? Is the drive file system toast? or can I recover the files?
Is there a way to recover the drive data and move it to the good drive?
Thank you for any help.

I would try two more things.

Use the fsck with the full option on the volume name not on the disk.

fsck -F <fstype> -o full < raw volume/slice name>

Also, you might try adding a new superblock. You should have a file that lists Alt superblocks. On my HPUX system it is under /var/adm/sbtab. Try 16, I believe there is an extra one there.

fsck -F <fstype> -b 16 <raw volume/slice name>

Failing all that, you may have to restore the disk.

Hope this helps!!

Um, no there's not. We need to remember that the various versions of unix do have some differences. On his system, that "newfs -N" did not actually modify the disk, but it did produce a list of alternate superblocks for him. His first was at 32.

I do agree that having come this far I would certainly try a few more superblocks, just to explore the depth of the disaster if nothing else. But on the other hand, I would not trust a filesystem after a disaster that was so severe that two superblocks were trashed.

Thank you for the replies. FreeBSD version of fsck is a bit diffrent than that of Linux of other *nxs.
I have found a site that says try the...
# fsck -F ufs -o /dev/ad0s1e
option but FreeBSD does not use the switches -F or -o all i get is
fsck: illegal option -- F
fsck: ? option?

I will try and use all the alt super blocks option. That might do some good. Also I read last night that i might beable to extract the data of the disk buy using..

# dd if=/dev/ad0s1e of=test2 bs=2k

Has anyone used this with FreeBSD and does it work? I do not know the right use of dd.

I also found a place that said to use this to fix the disk...
# newfs -o b=32 /dev/ad0s1e
But with that I get this...

newfs: ime: unknown optimization preference: use `space' or `time'.

So I am still at a loss. Thank you.

Hello to all that find this thread through Google

I had a similar problem with my HDD and FreeBSD saying there was a bad superblock.
I followed the first step of the procedure and discovered (to my relief) the backup superblocks.

Once past this point the next reccomendation was to use fsck -b 160 /dev/"my partition"
This doesn't work as FreeBSD's fsck command doesn't acknowledge the -b flag as valid.

The trick is to use fsck_ffs which *does* recognise the -b flag and takes the appropriate action. i.e. fsck_ffs -b 160 /dev/"my partition"

Second tip (don't flame me for it's obviousness, not everyone is a super sysop). Make sure you are have root access otherwise no errors will be corrected.

Third Tip. If it looks like your filesystem is in a really bad way, look at the -y flag in the man page. i.e. read man fsck_ffs looking for -y

I hope this is usefull for anyone else that has the problem.

Cheers,
Neil S Davenport