Server hang : fsck

[Michael Powell]

eras mus wrote:
[...]
> 
> As advice by Polytropon burnt alive CD And ran fsck manually.
>  # fsck -yfv /dev/ad4s1a
>  # fsck -yfv /dev/ad4s1d
> 
> are successful.
> But when ran
>  # fsck -yfv /dev/ad4s1e
> 
> It was messages as in
> 
> http://picpaste.com/img3-It4JOaph.jpg
> 

I suspect what you may be experiencing is magnetic media failure on your 
drive, which means it will need to be replaced with a new one. This can be 
verified by using the drive manufacturers diagnostic utility. The bulk of my 
experience around IDE/Sata drives is largely centered on Western Digital. 
They have a utility called WD Diags, which can be found in a bootable .iso 
form which I have on an old CD-RW disk.

When run there is a 'Quick' test and a more thorough in-depth longer one. 
The 'Quick' test is non-destructive, but will show you an error if there is 
a problem with the drive. The long test can sometimes repair a disk, but 
this depends on the drive's remap area being not full. Even though once I 
have observed a long test fix a drive and not destroy data, it is expected 
that the long test will wipe the drive. The remap zone is a space on the 
drive that it uses to map out bad sectors as they develop over time. When 
this space fills bad sectors cannot be mapped  out any longer and it is time 
to buy a new drive.

I would hesitate to simply use dump to backup this drive with the idea of 
using restore to copy everything over to a new drive. Should you try it and 
there is defective media you will find dump will stop when it hits the bad 
spot(s). Your bits are probably already in a damaged state. No amount of 
softwares like fsck can fix the underlying problem which is that the hardware 
needs to be replaced. If this is truly the case, the manufacturers utility 
can/will confirm.

If this is a case of bad media and the drive is up for replacement I would 
concentrate on preserving copies of all configuration information. This will 
enable you to put in a new drive and manually configure everything in the 
new install the same way as the old. Much of this is /etc, and 
/usr/local/etc, where /etc will have the base OS's config while 
/usr/local/etc has all configs for installed third-party applications.

There is also /var/db/pkg which contains pkg info for installed apps, and 
/var/db/ports which holds build config options for ports you have installed. 
If the system is very old and you are making a jump from let's say version 
6.2 to something like 9.2 release you would only refer to the options for 
hints on how to proceed; the ports have changed so much that you can't just 
simply copy the /var/db/ports directory over. If the system was the same, 
e.g. if the old machine had 9.2 and you were just putting it back to a new 
drive you could just copy.

In a case where the magnetic media in the drive has, or is failing, I would 
look towards starting over with a fresh install with the new drive. If you 
had _known_ good backups from the drive which were not so old as to be 
extremely out of date I would just restore these to the new drive. If you do 
not, and you have bad spots on the drive you'll find it's too late for that 
- dump will error out when it hits the bad spots. A fresh install is a lot 
of keyboard time but at the end you get back what you had if you have 
preserved all the old configuration details. Confirm the problem is media 
going bad, or already has gone bad using the mfr's diagnostic utility. This 
will point you in the direction you need to go if such is actually the case. 
(Bad media simply cannot be fixed with things like fsck)

-Mike