Hello,

I have a problem with my server :

Sometimes, this server is used to stop running. It doesn't shut down but it stops running (with a noise on the hard drive) and there's no other way to shut down than pushing the power button during a long time. I don't think that it comes from the hard drive because I have the same effect with two hard drives.

Here comes the best : Today it stops running during boot procedure and now, when I reboot the server, I have the following error message :

Buffer I/O error on /dev/hda2 device block 0 Buffer I/O error on /dev/hda2 device block 1 Buffer I/O error on /dev/hda2 device block 2 Buffer I/O error on /dev/hda2 device block 3 Buffer I/O error on /dev/hda2 device block 5 Buffer I/O error on /dev/hda2 device block 0 etc...

I have two questions :

Is there a way to recover data on /dev/hda2 ? (I tried linux rescue but it didn't find the linux installation) Is there a way to know why the server stops suddenly to run ?

Thank you for any help,

Jean LEE

try something like this. fdisk -l /dev/hda (no 1,2 etc just the drive) if it gives you back some partition table then you have hope. try to mount the drive with ro (read only option we do not need to change anything on it, we just want the data) If this fails for any reason, try to dd the whole disk to another (good one) and then mounting and perhaps fsck might give you your data back. Try in the archive there was an excelent post on this procedure just a few days ago.

Best luck,

Nikos Zaharioudakis

On 6/22/05, Jean Lee jean.lee@free.fr wrote:

Hello,

I have a problem with my server :

Sometimes, this server is used to stop running. It doesn't shut down but it stops running (with a noise on the hard drive) and there's no other way to shut down than pushing the power button during a long time. I don't think that it comes from the hard drive because I have the same effect with two hard drives.

Here comes the best : Today it stops running during boot procedure and now, when I reboot the server, I have the following error message :

Buffer I/O error on /dev/hda2 device block 0 Buffer I/O error on /dev/hda2 device block 1 Buffer I/O error on /dev/hda2 device block 2 Buffer I/O error on /dev/hda2 device block 3 Buffer I/O error on /dev/hda2 device block 5 Buffer I/O error on /dev/hda2 device block 0 etc...

I have two questions :

Is there a way to recover data on /dev/hda2 ? (I tried linux rescue but it didn't find the linux installation) Is there a way to know why the server stops suddenly to run ?

Thank you for any help,

Jean LEE

---

CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos

Depending on the disk, you can possibly get a vendor tool to disable bad block relocation. This way, if a block can't be read the disk will not do it's internal magic to remap the block to another part of the disk. Some vendors also offer a disk copy tool which can skip the unreadable parts, similar to what ddrescue ends up doing but can be significantly faster.

John.

Dag Wieers wrote:

On Wed, 22 Jun 2005, Nikos Zaharioudakis wrote:

...

try something like this. fdisk -l /dev/hda (no 1,2 etc just the drive) if it gives you back some partition table then you have hope.

Even when it fails to return a partition table there is still hope.

I actually had problems, fdisk -l didn't work, partitions couldn't be mounted read-only. But after ddrescueing the complete disk I still had 99.983% of my disk (about 30MB of the 160GB was lost, most of it on the recently formatted and therefor empty partition, only 2.2MB of real data was impacted)

Strangely, fdisk -l on the copied disk worked without a problem. According to ddrescues output:

Bad region size 32768 at position 4096 Bad region size 4096 at position 49152 ...

I verified fdisk's behaviour with strace and apparently it first reads the first 512 bytes, but then strangely reads the first 8k. Since that fails, I was out of luck.

...

try to mount the drive with ro (read only option we do not need to change anything on it, we just want the data)

Don't do this after a reboot, chances are the disk is dying, might go bad while using it and the filesystem might not recover from the problems anyway. If the system was still running, you might want to copy files off the filesystem (since the disk might not come back after a reboot). If you rebooted the system, use a rescue CD (knoppix) that has dd_rescue on it and use that to copy the complete block-device.

You can also download gnu ddrescue to your knoppix ramdisk, compile it and use that. It is more sophisticated and you can first recover the major working areas with a big blocksize and later refine the bad areas (when the disk might be even less reliable).

...

If this fails for any reason, try to dd the whole disk to another (good one) and then mounting and perhaps fsck might give you your data back.

dd will not work if you have bad blocks, it fails on the first bad block.

Also, before running fsck you might want to make a second copy, in case the fsck fails. You don't need to copy everything back from the broken disk, but instead try to refine copying the bad areas (some reports say freezing the disk in the freezer helps ?).

In my case it took 18h to copy the good parts, but refining the bad areas takes 4 secs for 1 bad block (512 bytes). So you might not want to do that at first or it could take a week (in my case 3 days for 30MB) refining every bad area.

-- dag wieers, dag@wieers.com, http://dag.wieers.com/ -- [all I want is a warm bed and a kind word and unlimited power] _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos

On Wed, Jun 22, 2005 at 04:35:02PM -0500, Johnny Hughes wrote:

OK ... the CentOS-4.1 SRPMS are on mirror.centos.org they are at: http://mirror.centos.org/centos/4/os/SRPMS

awesome. thanks.

On Wed, Jun 22, 2005 at 06:06:20PM -0500, Johnny Hughes wrote:

Also, what debuginfo we have for CentOS-4.x is going up right now to: http://vault.centos.org/debuginfo/

Cool -- I'll change to mirror offa that directly.