[CentOS] bad blocks showing up

[Bryan J. Smith <b.j.smith@ieee.org>]

From: Ted Kaczmarek <tedkaz at optonline.net>
> I have seen what I consider an exorbitant amount of ide drive failure
> lately, granted most of these are lower grade machines, but the
> percentage of drives failing seems to be much higher than I recall.

That's because ATA drives are spinning higher and higher, and people
aren't cooling nearly as good as they used to.

The typical, "commodity" ATA drive is typically rated for only 50,000
restarts with 8 hours of operation between, resulting a MTBF of
400,000 hours.  And that assumes the following "ideal" conditions: 

- Ambient drive temperature never exceeds 40 degrees C
- Drive is not powered 24x7 (most vendors recommend no more
  than 14x5 on their "commodity" models)
- Drive is spun up at least once every few weeks**

[ **NOTE:  This is a major reason why you should _never_ use
ATA drives a backup media if they are not going to be powered-on
regularly (like in an on-line/near-line backup system). ]

Now some vendors test their "commodity" drive lines and reserve
those that test to higher tolerances for "Enterprise" labeling, possibly
for the same ATA, or maybe a server SATA or SCSI drive.

Other vendors use completely different lines for "enterprise" drives,
using better lubricants, filters, mechanics, etc...

> Is their possibly something with ext3 that stresses drives more?
> Maybe the location of the journaling info? 

Naah, that would affect FAT systems and others too.

The main problem is the density, spindle, heat and "ultra-thin
manufacturing margin" of the drives these days.  Especially
given the increased spindles, the "cheap drives" just don't last
under the constant operation and heat at 7200rpm.

The "Big 3" manufacturers are Hitachi, Maxtor and Segate.
IBM, Western Digital and other vendors no longer manufacture,
and haven't for awhile.

Hitachi and Seagate have split-lines, commodity and enterprise.
Interface doesn't have anything to do with it, and even Hitachi
and Seagate have SATA and SCSI models that use the exact
same lines as their most commodity ATA ones.  Of course, they
also offer "Enterprise" ATA, SATA and SCSI models too, that are
rated for much higher tolerances.

Maxtor actually has a single commodity approach.  Then they test
drives against tolerances and rate them for MTBF and warranty
based on that testing.  I.e., all drives pretty much come off the
same line, but the "Enterprise" drives are the ones that test high,
while the "commodity" drives are everything left over.

I'm partial to Seagate, despite the extra 10-20% cost on the
commodity models, because they are giving 3-5 warranties as
standard.  They seem to do a little better on standard components,
but that's just my opinion.


--
Bryan J. Smith   mailto:b.j.smith at ieee.org