Re: Disk performance deteriated to unbearable levels

[Alberto Luaces <aluaces@udc.es>]

Miles Fidelman writes:

> 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.

All my drives have a RAW_VALUE for that parameter not equal to 0:

machine1$ sudo smartctl -A /dev/sdb | grep "Read\|Power_On"
  1 Raw_Read_Error_Rate     0x000f   108   099   006    Pre-fail  Always       -       18696503
  9 Power_On_Hours          0x0032   087   087   000    Old_age   Always       -       11987

machine1$ sudo smartctl -A /dev/sda | grep "Read\|Power_On"
  1 Raw_Read_Error_Rate     0x000f   111   086   006    Pre-fail  Always       -       35575453
  9 Power_On_Hours          0x0032   069   069   000    Old_age   Always       -       27906

Even with new drives:

machine2$ sudo smartctl -A /dev/sdb | grep -e "Read\|Power_On"                                                                                                                                           
  1 Raw_Read_Error_Rate     0x000f   117   100   006    Pre-fail  Always       -       131149163
  9 Power_On_Hours          0x0032   100   100   000    Old_age   Always       -       475
machine2$ sudo smartctl -A /dev/sdc | grep -e "Read\|Power_On"                                                                                                                                           
  1 Raw_Read_Error_Rate     0x000f   111   100   006    Pre-fail  Always       -       31090694
  9 Power_On_Hours          0x0032   100   100   000    Old_age   Always       -       285

Those are all Seagate drives. Maybe their raw value means something
different.

-- 
Alberto