[aklug] Re: hard drive issues

From: Christopher E. Brown <cbrown@woods.net>
Date: Sun Oct 04 2009 - 12:50:19 AKDT

On Sat, 3 Oct 2009, Greg Madden wrote:

> A few cosmic convergences happening with my IDE storage.
> 1. I have hda & hdb, both loose DMA settings reliably.
> 2. Smartmontools 'smartctl' reports a high count :
> 'Raw_Read_Error_Rate', 'Seek_Error_Rate', fortunately? the
> 'Hardware_ECC_Recovered' equals the 'Raw_Read_Error_Rate'.
> The 'Reallocated_Sector_Ct' is at zero which means that, afaikt, that
> nothing is physically happening, yet. Also the 'Current_Pending_Sector'
> & 'Offline_Uncorrectable' count is zero.
> It should be noted that the smartmon stuff reports errors but does not
> fix them.
> 3. It was mentioned Friday Nite the Steve Gibson's 'Spinrite' tools
> fixes magnetic media issues. Unwilling to spend $89 on a 'black box' solution
> I found the tools in Linux that do the same.
> http://smartmontools.sourceforge.net/badblockhowto.html
> A brief list of tools:
> smartctl -l selftest /dev/hda
> smartctl -A /dev/hda
> fdisk -lu /dev/hda
> Tune2fs -l /dev/hda3 | grep Block
> debugfs, cool tool .
> and "dd'
> A quick fix :'e2fsck with, at least, the -c option,
> which uses 'badblocks' and moves data, remaps bad blocks :-)
> Google is full of hits on the results of SMART enabled drives. Me
> thinks it causes much wasted time and anxiety. I mention this because
> the new Ubuntu 9.10 is using a new hard drive health tool that pops up
> on every boot telling the user that the hard drive is ABOUT to fail.
> I am maybe a litle closer to understanding hard drive issues :-) I
> have renewed interest in backups.
> ps, I used the 'System Rescue Cd' on an Ext4 partition.

You should keep in mind that modern drives keep an internal spare area and
bad block map. When the drive itself detects a failing sector it is
transparently remapped to another sector in the spare area.

Normally they only start showing perminant bad sectors _after_ they run
our of remap space. If badblocks via e2fsck or mkfs locks out a number of
blocks as "bad at the presentation layer" it normally means the drive is
on its last legs.

As I recall, this internal remap on multiple fail behavior became pretty
much standard back when standard drive sizes were < 500MB, before that a
low level format was needed to get the drive to do the internal mapping.

I remember using badblocks to lockout sectors on 40 - 500MB IDE and SCSI
drives until I could coupy out the data and low level, and on MFM and RLL
drives before that, but not since then.

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Received on Sun Oct 4 13:00:21 2009

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