Bad boot disk using F12

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Basher52
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Bad boot disk using F12

Post by Basher52 » Sat May 01, 2010 2:50 pm

Last night the boot disk on one of my servers using Fedora 12 seems to have given up :(
now I'm trying to read an image from it by using 'dd' and that seems to be able to read the entire disk, but not the partitions.

If i use parted i can see the partitions but not when 'ls /dev/sdc*'
this is what I mean:

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[root@kgdubben ~]# ls /dev/sd
sda  sdb  sdc  sdd  
[root@kgdubben ~]# ls /dev/sd*
/dev/sda  /dev/sdb  /dev/sdc  /dev/sdd
[root@kgdubben ~]# 
[root@kgdubben ~]# 
[root@kgdubben ~]# parted /dev/sdc
GNU Parted 1.9.0
Using /dev/sdc
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p                                                                
Model: ATA HDS722512VLSA80 (scsi)
Disk /dev/sdc: 124GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system     Flags
 1      32.3kB  107MB   107MB   primary  ext3            boot
 2      107MB   17.6GB  17.5GB  primary  ext3
 3      17.6GB  18.7GB  1078MB  primary  linux-swap(v1)  swap
 4      18.7GB  124GB   105GB   primary  ext3

(parted)
Is there a way for me to fix this? thus recreating the partitions so I can read them to an image backup that I can 'dd' back to another disk

also when trying to mount it I get this:

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[root@kgdubben ~]# mount /dev/sdd /mnt/sdd
mount: unknown filesystem type 'silicon_medley_raid_member'


btw, another thing. When I put the disk in the system I couldn't see it in /dev, I had to reboot but is that really necessary?
Last edited by Basher52 on Sun May 02, 2010 2:33 pm, edited 1 time in total.

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Post by Basher52 » Sat May 01, 2010 4:10 pm

UPDATE: I found something about the last 'btw' I wrote.
Gonna try this later to see if it works

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If the drive is in a RAID, or if it’s a separate sized drive for a disk upgrade, it’s a good idea to trigger the kernel driver to rescan information about the new disk.

In /sys/bus/scsi/devices, you’ll find a number of numbers that’ll correspond to your disk drives:
server devices # ls -1
0:0:0:0@
1:0:0:0@
2:0:0:0@

You can determine more information about the drive by cat’ing it’s model file:
server devices # cat "0:0:0:0/model"
ST3250410AS

Now, to cause the kernel to rescan the drive attached to the port, do this:
echo > "0:0:0:0/rescan"

Check dmesg now:
server devices # dmesg
---snip---
SCSI device sda: 488397168 512-byte hdwr sectors (250059 MB)
sda: Write Protect is off
sda: Mode Sense: 00 3a 00 00
SCSI device sda: drive cache: write back

Now, that’s pretty exciting, as this can be used to skip a reboot.  If you switch the drive, and trigger the rescan, it’ll update the drive information including the partition layout.  Make sure you don’t swap out your main system drive, otherwise your computer will freeze, and there will be data loss and possibly corruption.

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Post by Basher52 » Mon May 03, 2010 5:43 pm

Something weird happened. The hard disk seemed fine when I made an image of it in a Linux machine that didn't think it was a disk from a raid system. Anyhow, the problem is now fixed and the server is up and running again :) on a new disk that I restored the image on.
I wonder why the system made it read only and later just stopped working.
Can't find any funny stuff in any logs either.

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Post by Basher52 » Wed May 12, 2010 9:56 am

seemed that the Partition Table was no more... kind of.
I was successful of retrieving the vital data and move that to a new disk.
After that it was OK :)

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