[CentOS] was, PATA Hard Drive woes, is "SMART"

[RedShift]

On 11/03/10 19:04, m.roth at 5-cent.us wrote:
> Warren Young wrote:
>> On 11/3/2010 11:27 AM, m.roth at 5-cent.us wrote:
>>> Yeah, but I have problems with smartmon:
>>
>> More likely, problems with SMART.  S.M.A.R.T. is D.U.M.B. :)
>>
>> It's better than nothing, but sometimes not by a whole lot.
>>
>>> one server that's got two bad sectors, which SMART reports. I've
>>> followed the instructions on how to make the log messages go away, and
> fsck -c...
>>> but on reboot, SMART seems to ignore what badblocks found, and the
>>> irritating messages are back.
>>
>> It may be that SpinRite could fix that by forcing a remap.
>
> Dunno if we have SpinRite around here.
>>
>> Another option -- which I didn't mention because it probably isn't an
>> option for the original poster, but which may work with your servers --
>> is that some high-end RAID systems can do something like SpinRite at
>> level 4+, as can ZFS.  They call it resilvering.  I don't think these
>
> No joy - it's a plain SATA drive, the root drive on a server we use for
> backups. ext3, and no, I'm not going to change filesystem types.... The
> real thing is why does SMART ignore the results of badblocks (for those
> who aren't sure, that's invoked when you do fsck -c), and for that matter,
> why the drive (Seagate ST3170811AS) doesn't automagically relocate those
> blocks.
>
>          mark
>
>         mark
>
>


Auto relocation happens ONLY when writing to foobar sectors. The drive WILL NOT relocate sectors that you are reading from because it cannot trust the content.

SMART reports the number of sectors that have been reallocated. That means, the drive was writing to a sector, found out it was unreliable and decided to remap that sector. It is not abnormal for drives to develop _a few_ bad sectors over the years.