Xeon Woodcrest Preys On Opteron

[J. Clarke]

the fact that TLER has been on WD's RE/RE2 SATA
hard drives for at least the last 12+ months
suggests that you may be right, but my hunch is
that it's more complicated than that

Nope. The history is that WD IDE drives attached to various RAID
controllers were failing right and left. It turned out that the problem
was that the error recovery timeout on the WD drives was so long that the
controller timed out on attempted access before the error recovery timed
out and so the controller marked the drive as offline.

The fix was to shorten the timeout, but instead of doing this across the
board WD instead make "RAID Edition" drives and charged extra for them.

Classic case of "if life hands you a lemon make lemonade".

SATA drives appear (to me, with my very limited
1st hand experience) to be a very valid choice
for single use RAID sets

are SATA drives now becoming a real alternative
to more expensive SCSI drives for server RAID sets?

as well as the still unanswered question of does
TLER help within usage in a *server* RAID set?

It's very simple. If you are using a WD drive in a RAID then you need TLER
unless the manufacturer of the RAID controller states _specifically_ that
you do _not_ need it. The safer choice is to simply avoid WD for mission
critical systems.

As for SATA being acceptable for mission-critical RAID, it's really a matter
of finding a host adapter that you trust and that has the performance you
need. The whole point of RAID is that drive failure is a given and so the
reliability of individual drives has little effect on system
reliability--the lifecycle cost for SATA might be higher, lower, or the
same as SCSI--I don't know of any direct comparisons that have been run.

It can be argued that it is potentially superior to SCSI in that a properly
designed SATA RAID controller has each drive on a separate channel and so a
drive failure that affects the interface (which can happen, I've seen it
with both SCSI and IDE systems) remains isolated with SATA while with SCSI
it takes down the whole channel until the defective drive is removed. In
practice however the RAID controllers for SATA have for the most part been
relatively "lightweight" units that either lacked some reliability features
such as battery-backed cache or offered relatively poor performance.

 

[J. Clarke]

I think that's the point of the Caviar RE line

Actually the point of the Caviar RE line is to make a buck by changing a
couple of bits in a ROM.

and the Seagate Nearline
class.

Not clear what Seagate is doing there, but the NL35 series seems to allow
higher nonoperating shock than the 7200.10, so clearly there's _some_
difference.

Obviously there's a market for an uprated SATA drive; remember the
Deskstars which were rated for a max hours per monthly cycle a couple of
years back? On top of the click of death saga, finished them off.

Best Buy and CompUSA and Staples and the rest seem to have shelves full of
Deskstars so maybe you need to inform them that the product was "finished
off" several years ago.

 

[George Macdonald]

Actually the point of the Caviar RE line is to make a buck by changing a
couple of bits in a ROM.

They do specify a MTBF/duty cycle for the RE & RE2... whatever that means
when it fails.

Not clear what Seagate is doing there, but the NL35 series seems to allow
higher nonoperating shock than the 7200.10, so clearly there's _some_
difference.

So this means they're selling umm, desktop drives which are err, not as
good as they could be at withstanding non-operating shock? Funny... I
wonder what the difference in mfring cost is?

Best Buy and CompUSA and Staples and the rest seem to have shelves full of
Deskstars so maybe you need to inform them that the product was "finished
off" several years ago.

Under new management now and those retail drives are not what most people
have in their systems, purchased from an OEM.

 

[willbill]

willbill wrote:


Nope. The history is that WD IDE drives attached to various RAID
controllers were failing right and left.

ok. i'll accept that as fact for now. thank you.

It turned out that the problem
was that the error recovery timeout on the WD drives was so long that the
controller timed out on attempted access before the error recovery timed
out and so the controller marked the drive as offline.

The fix was to shorten the timeout, but instead of doing this across the
board WD instead make "RAID Edition" drives and charged extra for them.

Classic case of "if life hands you a lemon make lemonade".




It's very simple. If you are using a WD drive in a RAID then you need TLER
unless the manufacturer of the RAID controller states _specifically_ that
you do _not_ need it. The safer choice is to simply avoid WD for mission
critical systems.

heh. i'm about to trade 2 Seagate 250GB
SATA (7200.9) for 2 160GB SATA WD (JD?), with
my sister

which i plan to use RAID-1

so i get to find out

as far as i can tell/know, it doesn't make a bit
of difference for RAID use in a single use PC

As for SATA being acceptable for mission-critical RAID, it's really a matter
of finding a host adapter that you trust and that has the performance you
need. The whole point of RAID is that drive failure is a given and so the
reliability of individual drives has little effect on system
reliability--the lifecycle cost for SATA might be higher, lower, or the
same as SCSI--I don't know of any direct comparisons that have been run.

It can be argued that it is potentially superior to SCSI in that a properly
designed SATA RAID controller has each drive on a separate channel and so a
drive failure that affects the interface (which can happen,

interesting thought. thank you for that

I've seen it
with both SCSI and IDE systems) remains isolated with SATA while with SCSI
it takes down the whole channel until the defective drive is removed.

i'm curious about this

you are saying that given a SCSI 3 disk RAID-5 array,
with a decent RAID controller, that if you pull out
the power to the middle disk of the array, that the
whole thing takes a dive?

i find that a bit hard to believe

but all ears, bill