What are the possible action regarding having bad sector in my ext4 root partition?

jao_madn · October 12, 2011, 6:17pm

Hi,

I would like to ask about actions taken if any regarding having a few bad sector (67 bad sector according to DISK UTILITY) on my root ext partition except from buying a new HD and cloning it since my laptop is a 1 year old.

Question:
About clonzilla before this bad sector happens i used clonezilla image features for at least 1 year for a reason that i can compress the root partition to a smaller files and not the entire blocks or partition which happens when using dd or ddrescue. Now i can't use clonezilla since it has problem when HD suffering bad sector im stuck in error msgs in clonzilla. Now im using ddrescue which image the entire partition

I would like to ask a question i theres any effect in the future about the bad sector in the image i created using ddrescue when i restored. Example does bad sector whill occur in the new HD if i will restore the image i created.

Is it possible to repair a bad sector or something like label it bad sector so that no more read and write to it. i stumble this nice tuts Smarttools repair HD but its for ext2 and ext3.

Corona688 · October 12, 2011, 6:27pm

First off, understand that modern hard drives ("modern" as in "last 15-25 years") have bad-sector remapping. When they spot a sector going bad, they take its contents and put it in a 'spare' location without telling you. So: your hard drive doesn't have a bad sector.

It has so many bad sectors that it's run out of spares. That could be a quarter of the drive or more, gone bad. This drive is not safe to use. Get your data off and stop using it before it betrays you.

You can't low-level format anymore. The densities they have these days, they only have the precision to do that at the factory. Dead sectors are dead for keeps.

A 'sector' is just a collection of zeroes and ones, there's not a magic combo of 512 bytes that makes a sector go bad. dd_rescue is safe. bad sectors can't be transferred. dd_rescue can't even read them, it fills in zeroes and skips.

Did you dd the entire disk, or just the partition?

jao_madn · October 12, 2011, 7:21pm

corona688:

First off, understand that modern hard drives ("modern" as in "last 15-25 years") have bad-sector remapping. When they spot a sector going bad, they take its contents and put it in a 'spare' location without telling you. So: your hard drive doesn't have a bad sector.

It has so many bad sectors that it's run out of spares. That could be a quarter of the drive or more, gone bad. This drive is not safe to use. Get your data off and stop using it before it betrays you.

You can't low-level format anymore. The densities they have these days, they only have the precision to do that at the factory. Dead sectors are dead for keeps.

A 'sector' is just a collection of zeroes and ones, there's not a magic combo of 512 bytes that makes a sector go bad. dd_rescue is safe. bad sectors can't be transferred. dd_rescue can't even read them, it fills in zeroes and skips.

Did you dd the entire disk, or just the partition?

Thanks for the reply

I ddrescue the partition only in which is root,
I just concern with my root since all the programs bin location.
Am i right doing a partition dd image on my root partition and rsync to external the home files or partition

Corona688 · October 12, 2011, 7:25pm

You might want to save the boot sector somewhere, too.

# sda being whatever disk your system sees it as.  sda, NOT sda1.
dd if=/dev/sda count=64 > bootsector.backup

And you're sure you don't need any of the other partitions?

jao_madn · October 13, 2011, 9:00am

corona688:

You might want to save the boot sector somewhere, too.
# sda being whatever disk your system sees it as.  sda, NOT sda1.
dd if=/dev/sda count=64 > bootsector.backup
And you're sure you don't need any of the other partitions?

Thanks again..

I already backup the MBR and partition table..

In addition to partition table..Can i restore the same partition table to another the same size HD. How about larger from the original..

Corona688 · October 13, 2011, 11:27am

As long as the drive is equal in size or larger, you can.

After you restore your partition table, linux won't know about the new partition layout yet. It needs to be told to reread it. fdisk can do that -- just fdisk /dev/sda and immediately write back the same partition layout.