Re: Disk performance deteriated to unbearable levels

[Miles Fidelman <mfidelman@meetinghouse.net>]

Stan Hoeppner wrote:
> On 11/9/2011 1:34 AM, Bob Proulx wrote:
> > Miles Fidelman wrote:
> > > try smartctl -A /dev/sda
> > >
> > > that will give you a much longer list of statistics collected by the drive
> > >
> > > the one I always look at first is the absolute value of "raw read
> > > errors" - if that's higher than 0, the drive is starting to fail,
> > > and its internal code is spending more and more time trying to read
> > > and re-read data off the media
> > Excellent information!
> Not really.  The numbers are not absolutes.  And they differ among
> manufacturers.  S.M.A.R.T. is a data format standard for "drive health",
> but it does not dictate "value" standards for the field contents.
>
> For the end user, attempting to interpret some S.M.A.R.T. data for some
> makes of drives is hit or miss.  I would say as a general rule that one
> should contact the drive manufacturer if s/he sees S.M.A.R.T. error
> counts rise.  The drive may or may not be failing.

Specifically for "raw read error" - in the format

ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000b   088   088   062    Pre-fail  Always       -       3342368

I've found, across many different dries, that the "VALUE" field (which is a relative field calculated over time) is generally useless, while the RAW_VALUE field is almost always indicative of pending failure if it's value is anything other than 0.
















--
In theory, there is no difference between theory and practice.
In<fnord>  practice, there is.   .... Yogi Berra