Which SATA drives for large RAID 5 array?

[Eli]

I'm putting together an iSCSI storage array in a 3U hot-swappable
chassis. Up to 15 drives, though I'll start with 7 to 10, depending
on individual the drive size.

Which current line of drives would you recommend for this task?

- Western Digital's "RAID Edition"?
- Seagate, with the 5 year warranties?
- Some other?

Speed is much less of a concern than reliability. The array will be
worked fairly hard.

Are there actually any differences between Western Digital's RAID
Edition and their other SATA drives?

Is Seagate's 5 year warranty any indication of their suitability to
high load tasks, or is more of a marketing angle?

 

[dg]

The RAID edition drives have 1 major difference. I am not going to explain
it perfectly, know that now, I only read the info once. With ordinary SATA
drives if the drive takes too long to respond, the RAID controller MIGHT
assume that the drive is bad and run the array in a degraded state. As you
can tell, this could cause major problems. If you had 2 drives assumed bad
just because they took too long, your raid 5 array would die.

I am under the impression that the RAID edition drives do something out of
the ordinary to let the controller know they are NOT dead. Check WD
website, they have a white paper on the new RAID drives.

The seagate 5 year warranty may be purely marketing. I suppose you could
look at the MTBF ratings and see if they make you feel better. The 5 year
warranty IS purely a marketing strategy, I mean, why else would they do it?
Im not saying the drives aren't good, but what other reason could they have
for extending the warranty-they want people buying their drives.

--Dan

 

[Arno Wagner]

I'm putting together an iSCSI storage array in a 3U hot-swappable
chassis. Up to 15 drives, though I'll start with 7 to 10, depending
on individual the drive size.

Which current line of drives would you recommend for this task?

- Western Digital's "RAID Edition"?
- Seagate, with the 5 year warranties?
- Some other?

Speed is much less of a concern than reliability. The array will be
worked fairly hard.

Make sure you have hot or at least cold spares. Personally, with >8
drives I would not feel comfortable without a hot spare or RAID6.

Are there actually any differences between Western Digital's RAID
Edition and their other SATA drives?

The RAID edition will stop recovery atempts on read errors after a
short time and allows the controller to se a failed sead insted
of a timed out (by the controller) disk access. I think this is fairly
useless, unless you are running a degraded array for a longer time.
If you do that you are practically begging for your data to be destroyed.

Is Seagate's 5 year warranty any indication of their suitability to
high load tasks, or is more of a marketing angle?

Definitely higher reliability. Exchanging a drive under warranty
causes significant cost with the manufacturer.

Arno

 

[J. Clarke]

Make sure you have hot or at least cold spares. Personally, with >8
drives I would not feel comfortable without a hot spare or RAID6.


The RAID edition will stop recovery atempts on read errors after a
short time and allows the controller to se a failed sead insted
of a timed out (by the controller) disk access. I think this is fairly
useless, unless you are running a degraded array for a longer time.
If you do that you are practically begging for your data to be destroyed.


Definitely higher reliability. Exchanging a drive under warranty
causes significant cost with the manufacturer.

Which cost is built into the price.

 

[Arno Wagner]

Arno Wagner wrote:

Which cost is built into the price.

Correct, but prices have to be competitive and Seagate
is not massively more expensive than others...

Arno

 

[J. Clarke]

Correct, but prices have to be competitive and Seagate
is not massively more expensive than others...

Approximately $5 difference between Seagate and the lowest-price drive I
could find in 80 GB. Remember that the cost of warranty repair is
amortized over all drives sold.

 

[Arno Wagner]

Arno Wagner wrote:

Arno Wagner wrote: [...]
Definitely higher reliability. Exchanging a drive under warranty
causes significant cost with the manufacturer.

Which cost is built into the price.

Correct, but prices have to be competitive and Seagate
is not massively more expensive than others...

Approximately $5 difference between Seagate and the lowest-price drive I
could find in 80 GB. Remember that the cost of warranty repair is
amortized over all drives sold.

Yes. That would mean they expect to have low-rates of warranty repairs
in the 5 years they need to do them. Exactly my point.

Arno

 

[J. Clarke]

Arno Wagner wrote:

Arno Wagner wrote: [...]
Definitely higher reliability. Exchanging a drive under warranty
causes significant cost with the manufacturer.

Which cost is built into the price.

Correct, but prices have to be competitive and Seagate
is not massively more expensive than others...

Approximately $5 difference between Seagate and the lowest-price drive I
could find in 80 GB. Remember that the cost of warranty repair is
amortized over all drives sold.

Yes. That would mean they expect to have low-rates of warranty repairs
in the 5 years they need to do them. Exactly my point.

I see. So what return rate would that $5 premium support and what would you
consider to be a "low return rate"?

I'm surprised that you've bought into this particular piece of marketing
hype. If duration of warranty bore any relation to reliability then
Hyundais would be the most reliable cars in the world.

 

[dg]

I'm surprised that you've bought into this particular piece of marketing
hype. If duration of warranty bore any relation to reliability then
Hyundais would be the most reliable cars in the world.

The way I see it, the seagate drives COULD be more reliable, but the
warranty IS marketing intended to boost sales. Im not saying the drives are
better or worse than anything else, just that the warranty is marketing for
sure.

--Dan

 

[Arno Wagner]

Arno Wagner wrote:

Arno Wagner wrote:

[...]
Yes. That would mean they expect to have low-rates of warranty repairs
in the 5 years they need to do them. Exactly my point.

I see. So what return rate would that $5 premium support and what would you
consider to be a "low return rate"?

I'm surprised that you've bought into this particular piece of marketing
hype. If duration of warranty bore any relation to reliability then
Hyundais would be the most reliable cars in the world.

Well, my main indication is that not so long ago all warranties were
reduced because of cost (or so they claimed). Of course I can be wrong
on this, it is just my personal interpretation. It is also possible that
most people don't bother doing a warranty return after a disk is a year
old or so.

I don't generally think "longer warranty" = "better product".
It is just my opinion in the current situation for Seagate, also
supported by indications that thir drives are actually in the
upper ranks for reliability and that their 5 years may actually
cost them the same as one year for, say, Hitachi.

But let's agree to disagree on what the warranty time implies.

Disregarding the warranty issue, I still think that Seagate makes
pretty good drives today.

Arno

 

[Arno Wagner]

The way I see it, the seagate drives COULD be more reliable, but the
warranty IS marketing intended to boost sales. Im not saying the drives are
better or worse than anything else, just that the warranty is marketing for
sure.

Of course it is marketing. But is it marketing were accounting and
enginnering said "yes, no problem that will not cost much" or is
is a risky step that may become a significant cost factor?

At the moment it is really anybodys guess. Mine is it is the former.
I should perhaps have expressed my opinion a bit more carefully.
I am sorry if that caused confusion.

Arno

 

[J. Clarke]

Arno Wagner wrote:

Arno Wagner wrote:
[...]
Yes. That would mean they expect to have low-rates of warranty repairs
in the 5 years they need to do them. Exactly my point.

I see. So what return rate would that $5 premium support and what would
you consider to be a "low return rate"?

I'm surprised that you've bought into this particular piece of marketing
hype. If duration of warranty bore any relation to reliability then
Hyundais would be the most reliable cars in the world.

Well, my main indication is that not so long ago all warranties were
reduced because of cost (or so they claimed).

Actually, they were all reduced because one manufacturer reduced them in an
effort to produce the cheapest drive on the market and the others like
lemmings followed suit in the mistaken belief that he who made the cheapest
drive won. They've since apparently found that with hard disks comparable
in price to a tank of gas price differences less than the cost of a
hamburger make little difference in comparison with perceptions about
quality and performance.

Of course I can be wrong
on this, it is just my personal interpretation. It is also possible that
most people don't bother doing a warranty return after a disk is a year
old or so.

I don't generally think "longer warranty" = "better product".
It is just my opinion in the current situation for Seagate, also
supported by indications that thir drives are actually in the
upper ranks for reliability and that their 5 years may actually
cost them the same as one year for, say, Hitachi.

Well, the Hitachi 80 gig with 3 year warranty costs $2 more than that
Western Digital with 3 year warranty, and the Seagate with 5 puts 3 bucks
on top of that.

But let's agree to disagree on what the warranty time implies.

Disregarding the warranty issue, I still think that Seagate makes
pretty good drives today.

I'd agree with that assessment.

 

[J. Clarke]

Of course it is marketing. But is it marketing were accounting and
enginnering said "yes, no problem that will not cost much" or is
is a risky step that may become a significant cost factor?

Every drive manufacturer in the business except Samsung has been making
disks longer than some of their engineers have been alive. With that kind
of experience, deciding warranty terms is not "a risky step". They know to
a high degree of precision what percentage of their drives will fail in a
given time period and what the cost of RMAing those drives will be. The
only risk is that they'll come out with a defective design like Fujitsu did
a while back, and there the killer for Fujitsu probably wasn't the warranty
cost but the data recovery cost imposed on them by the court.

 

[dg]

Every drive manufacturer in the business except Samsung has been making
disks longer than some of their engineers have been alive. With that kind
of experience, deciding warranty terms is not "a risky step". They know
to
a high degree of precision what percentage of their drives will fail in a
given time period and what the cost of RMAing those drives will be. The
only risk is that they'll come out with a defective design like Fujitsu
did
a while back, and there the killer for Fujitsu probably wasn't the
warranty
cost but the data recovery cost imposed on them by the court.

When I got in on this thread I almost said the same thing, the manufacturers
know the existing warranty claims and can easily calculate if they will lose
money. However, I quickly realized that if their warranty was previously 3
years, the only warranty data they have will be data on drives failing
within the 3 year period. Since they don't RMA drives older than 3 years,
they don't have the failure numbers drives of that age (at least nothing
close to representation of their entire production). Personally, I think
that if a drive lasts 3 years there is a good chance it will last 5, so the
extra warranty isn't a huge risk. But thats nothing more than a guess and
limited experience with hard drive failure.

--Dan

 

[J. Clarke]

When I got in on this thread I almost said the same thing, the
manufacturers know the existing warranty claims and can easily calculate
if they will lose
money. However, I quickly realized that if their warranty was previously
3 years, the only warranty data they have will be data on drives failing
within the 3 year period. Since they don't RMA drives older than 3 years,
they don't have the failure numbers drives of that age (at least nothing
close to representation of their entire production). Personally, I think
that if a drive lasts 3 years there is a good chance it will last 5, so
the
extra warranty isn't a huge risk. But thats nothing more than a guess and
limited experience with hard drive failure.

You're assuming that there is a constant warranty period for all drives,
that RMA drives are their only source of information on reliability, and
that statistical sampling is not valid. The actual warranty runs all over
the place depending on contractual obligations--the 3 or 5 or whatever is
the warranty on retail-boxed drives, that represent a tiny minority of
overall production. Also that they don't do durability testing on their
drives--if they are typical of other manufacturing companies somewhere they
have a lab full of drives being tested to destruction, that allows
statistical information on failure rates to be determined for longer
periods than any warranty.

Seagate spends over a billion dollars a year in product development--keeping
a lab full of drives under long-term test can be done for less than a tenth
of a percent of that budget.

 

[Arno Wagner]

When I got in on this thread I almost said the same thing, the manufacturers
know the existing warranty claims and can easily calculate if they will lose
money. However, I quickly realized that if their warranty was previously 3
years, the only warranty data they have will be data on drives failing
within the 3 year period. Since they don't RMA drives older than 3 years,
they don't have the failure numbers drives of that age (at least nothing
close to representation of their entire production). Personally, I think
that if a drive lasts 3 years there is a good chance it will last 5, so the
extra warranty isn't a huge risk. But thats nothing more than a guess and
limited experience with hard drive failure.

It is a difficult question and I admit my initial statement was not
careful enough. Until HDD capacities and technologies stabilize for
longer time intervals (decades), like other standardised engineering
products already have (think screws, lamps, transistors, cabeling,
etc.) it will be guesswork.

Accelerated ageing techniques are really quite limited in that they
can overlook whole problem areas. And it is a moving target, since the
designs vary to some degree during the lifetime of a specific model
when the design is streamlined.

Arno

 

[bill]

Actually, the major expense for providing a warranty is:
(1) administration
(2) the "expense" which is charged against earnings according to expected
failures. (It's a per unit charge based on engineering calculations.)

The actual cost of replacing a relative handful of drives is negligible.

As buyers (in total) don't get anything out of the majority of the expense
incurred to provide a longer warranty, it makes sense to reduce the warranty
and reduce the price. (Unless you happen to be the person with a drive that
craps out after the shortened warranty.)

At least it would make sense if we were all sensible. But most of us aren't
and we do equate a longer warranty with higher quality. I sincerely doubt
Seagate would switch to parts of lower quality if the warranty were one year
instead of five (depending on where you buy the drive.) Reputation still
counts.

By the way, is it my imagination or do I see Seagate drives with shorter
warranties at some of the big box stores?? The ones that run specials on a
different drive every week.

Bill