[aklug] Re: hard drive issues

On Sun, 4 Oct 2009 15:50:19 -0500 (CDT)
"Christopher E. Brown" <cbrown@woods.net> wrote:

> 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.

Thanks, Google did a study on predicting hard drive failures from SMART
data. It was done about 5 years ago but, I believe, their conclusion
was SMART wasn't all that accurate of a predictor.

http://research.google.com/archive/disk_failures.pdf
>
>
> 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.

-- 
Peace with Love
Greg Madden
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