The Radified Guide to Booting from a SCSI Drive implies that SCSI will deliver better performance than SATA.  However, when looking at the WD Raptor in a single-user (not server) environment, it outperforms a wide variety of SCSI (SAS) drives – even those running at 15K RPM (see  Single-User Performance).  Additionally, the speed of the interface (i.e., whether SATA or SCSI in Gb/s) isn't a limiting factor in hard disk drive performance, since the bandwidth is so much higher than what a SATA or SCSI drive can deliver anyway.

True, the WD Raptor is high-end SATA drive, but doesn't this comparison suggest that framing the problem in terms of the interface ("SATA versus SCSI") is misleading?

All comments are welcome.

An article examining SCSI versus SATA found the following.


Quote:

Frankly, I was surprised by the results!  They show that SATA has a performance advantage!  10K RPM Raptor SATA drives appear to be on par with the performance of even a 15K RPM SCSI drive, and with NCQ, SATA even holds a very significant lead! … Now keep in mind that we're strictly talking about hard drive performance.  Take a look at the "XP Booting" benchmarks in the last graphic -- you'll notice that is the area in which SCSI holds one of the only advantages to SATA.  This is due to CPU utilization -- SCSI drives simply don't use as much CPU power to run, leaving more CPU time for the rest of the system.  Based on those numbers, if you are looking to build the fastest possible computer, it does appear that SCSI holds onto a very marginal performance lead. If you are only concerned with getting the highest disk throughput possible, then SATA with NCQ is the way to go!  I should also add that given the right SCSI drive (i.e., a 146GB 15k RPM), you can still beat the performance of the 74GB Raptor with NCQ, but your costs will be three to four times higher.

Source:  SCSI vs SATA, Which is Faster?

I think the "SCSI is faster" mentality developed back in the ATA 33 days when the speed of the interface WAS the limiting factor.  SCSI can still outperform SATA in high end server RAID configurations.  On a desktop, I think it would be difficult to see the same performance.  

To say the least, I don't think that SCSI will give nearly enough performance increase to justify the increased cost.  SCSI controllers and drives are expensive.  You could get 3 WD Raptor drives and put them in RAID 5 for the same price as a good SCSI controller and drive.  Just thinking about the performance of RAIDed Raptors gets me excited.

Thanks, MrMagoo, for the reply.

But, why does the WD Raptor deliver such solid performance?

If you compare the hardware specifications of the Raptor (e.g., Access Time and Transfer Rate) to other high-end SCSI drives (e.g., Seagate Cheetah 15K.4), the latter are more impressive than the former.  Yet, the Raptor still delivers superior performance in a single-user environment.  I would not expect this to be so.

hi pleo.

most scsi drives are designed for server use. in other words they're designed to optimize performance in of randomly accessed data, which is how a server basically, works .. gathering data here and there, from all parts of a disk, and writing data (uploaded data), but less of that.

a single-user, on the other hand, retrieves data more sequentially.

i'm simplifying, but my point is that disk manufacturers can (& do) write *firmware* to optimize these different patters of disk access, which is why ide/sata drives are able to perform closer to scsi drives in certain benchmarks than the number you mentions (seek/access) would otherwise indicate.

i can say that upgrading from a 7200-rpm ide (not sata) to 10-K rpm scsi was a "wow" thing.

I have used the raptor-based machines of two friends, which *did* seem zippy, but lacked the same level of responsiveness i observed on 15k-rpm scsi based machine.

the coolest thing about scsi (i'm talking about 15k-rpm scsi here) is its *responsiveness*. if you haven't played with a 15k scsi based rig, it's hard to describe, but you actually feeler synchronized with the machine, whereas with ide/sata, you feel a certain clunkiness.

i also feel that benchmarks can't adequately capture this sense of responsiveness i'm talking about.

is it worth it? is scsi worth the extra cost? that's the *real* question. for most, probably not, but it depends on what the user is doing.

i regularly get mail from folks asking if they think scsi would be worth it for them. if i remember, i'll post such a mail at the end of this post, (maybe *after* it, so I don't hit the 9999 character limit).

since my days of scsi, i have moved on from pure performance to *reliability* .. and there's where scsi drives shine. they are made to higher standards (designed for hard 24x7 enterprise use).

i think if somebody has the money, they won't be disappointed with the performance (and reliability) they experience with scsi, but most aren't going to go that way.

the cost of the adapter must be factored in, but remember, you can take the adapter with you to you next rig/motherboard, so the number don't correlate as you might expect.

also, there is one drive that now has its firmware tweaked for desktop (not server) use, and that drive is the one to get. i forget off the top of my head ... fugitsu mag, maybe?

i used to have lots of money to play with, and scsi was fun. now that i have lawyer's bills, i don't buy scsi anymore. but many people have buckets of money (like i used to).

scsi drives spin faster (lower rotational "latency") and they have big-ass actuators .. to move the read/write heads around faster.

here's that email from a guy considering scsi, and what he plans to do with it:

I've done my best to research quite a bit about SCSI and I think it is a viable option.  My current setups is using SATA drives, most of them are 10k WD Raptors, some in RAID-0.

Audio editing and recording is a walk in the park in terms of hard drives these days, you can use almost anything on the market and you won't have any problems.  You'd get away with a single 7200rpm IDE drive.

The problem happens when you do music composition and sampling, that's when hardware requirements soar off the map.  I do large projects involving simulating orchestras, and the software products available on the market are amazing for doing that.  But the audio data libraries involved span dozens of gigabytes in size.  A typical orchestra has anywhere between 40 and 100 players, and to emulate that, the software draws on raw audio recordings of real instruments playing single musical notes.  In a piece of music, these "players" can be playing many notes very quickly, one after another.  You can potentially have hundreds of files being accessed at precisely the same time.

Because the libraries are gigabytes in size, they cannot be completely loaded into RAM, so they reside on the hard disk.  The software is engineered to pre-load into RAM the first few kilobytes of every single audio file as a buffer so that they can be triggered immediately in real-time with nearly 0 latency.  As soon as a note is triggered, the software calls on the hard drive and streams the rest of the audio data as necessary.

I've run into bottlenecks where disk access is too slow, and it cannot stream data from the hard disks fast enough when too many notes start playing at the same time.  The result is pops and clicks in the audio output.  I have tried increasing the size of the pre-loaded buffer so that it has more time to get data from the hard disks, but I end up running out of RAM.  So my endeavor now is to get hard drives with faster instantaneous access times, SCSI being the natural solution.

To compound this, I have several machines that are networked to share this job which operate simultaneously because one machine could never handle it all.  Each machine has similar specs - dual core CPU, 3GB RAM, and 2 or more 10k SATA drives.

So the hard drive operations are 100% random reads, no writes at all.  Do you think it's safe to say that 15k SCSI u320 will offer a considerable improvement from the 10k SATAs given all this rubbish i've just explained?

Cheers

just to recap (cuz i said a lot), i think the key points are that:

1. the low seek/ access times of (15k-rpm) scsi drives scsi drives provide a level of *responsiveness* that you can't get with 10k-rpm sata drives .. no matter *what* (artificial) benchmarks say. you feel one-with-the-machine.

2. scsi drives, which are designed for 24x7 enterprise, are built to higher standards than their sata counterparts, and are therefore more reliable.

3. the average joe computer-user isn't going to find the cost diff "worth it" for scsi. if you read my scsi guide, you know the main point i make is "scsi is not for everyone". with 10k-rpm sata, i'd now say that "scsi isn't for most people".

4. the firmware of scsi drives (all but one) is programmed differently than that for a sata drive.

5. the more a user does with his system and the more intensive things he does with it, i feel, the more he will appreciate "the feel" of a system based on a 15k-rpm scsi drive.

in the old days, when the scsi/ide wars were raging, i'd find it funny that someone who had never used a scs-based system would tell someone else, that scsi wasn't worth it FOR THEM.

Rad, thank you for the reply.  Your comments about optimizing the firmware for single- versus multi-user environments makes sense.

Concerning reliability, it is interesting to note that Seagate offers a 5 year warranty on the Cheetah (15K RPM SCSI) hard drive family – the same warranty as Western Digital on the Raptor.  Of course, the Raptor is a high-end SATA unit, and other more commonplace SATA drives may indeed be less reliable than SCSI units.

Rad, I believe I may be able to reconcile, on the one hand, your observation that the WD Raptor doesn't have quite the same responsiveness as SCSI drives (Reply #4); and, on the other hand, the published benchmarks showing that the Raptor exhibits faster real-world performance (Reply #0).

As compared to the first-generation, the second-generation Raptor drives are 14% faster; and, the third-generation units are 17% faster than the second.  Thus, if you were experiencing a first-generation model of the Raptor, you might have concluded that they are not as fast as SCSI, while at the same time that the real-world benchmarks of a third-generation Raptor presently show it to be faster (in a single-user environment) than SCSI.

Could this explain the discrepancy?

Returning to the reliability issue, it is worthwhile to note that the WD Raptor has a 1.2 million hour MTBF specification, while the Seagate Cheetah 15K.4 SCSI, for example, is rated at 1.4 million hours – i.e., they are essentially the same.

A clarification on the prior post:


Quote:

Because of the clear window, the Raptor X has an MTBF rating of 600,000 hours (68.5 years), whereas the normal Raptor has an MTBF double of that (1.2 million hours or 137 years).  However, this shouldn't be too great a concern as both drives are covered by a five-year warranty.

Source:  WD Raptor

Rad, this article provides a succinct history of the Raptor.  If your experience with the Raptor not being as “responsive” as SCSI occurred prior to January, 2006, then it is certainly based upon a first- or second-generation version of the drive rather than today’s current third-generation model.  The benchmarks showing the single-user superiority of the Raptor to many SCSI drives are, of course, based upon a comparison to the third-generation model.

having the same waranty period doesn't mean the drives are equally reliable.

i'd wager they have to make good on those raptor warantys far more than on those for their cheetahs.

replacing a drive, even if under waranty, still suks.

there was a study published recently (a few months ago?) by google, who owns a zillion hard drives, and they basically said drives start dying agter only 2 years of operation .. i think the number was somewhere around 7-12% (from memory) .. each year after the 2nd.

surprised you didn't see that. interesting data.

but the big message was that the mtbf figures published by drive manufacturers are essentially bunk. wishful thinking. not real world, where we inadvertantly bang and kick our pc's, crach into the desk holding our pc's.. etc. i'm sure their test drives operate in vastly different environments (climate controlled, etc.).

have to be careful about using the word "faster" when it comes to hard drive benchmarks, which are artificial routines, designed by some benchmark creator .. which may or may not represent how you & I use our hard drives.

for example, when you use the % increase figures for raptors, does that mean they decreased their respective seek/access times for each generation, or simply boosted str's (sustained transfer rates), which is typically a product of data density.???

these numbers given are often subjective, and can be analyzed in numerous ways.

what are the respective seek/access times for each raptor generation?

the wiki on raptors does not give any seek/access specs, which is the key spec that translates into responsiveness.

none of the raptors-based systems i tried contained the clear-window drive, so i'm sure it wasn't the most recent version (which is cool).

in my most recent system design (last year), i selected a raptor for my boot/system drive:

http://radified.com/computer/computer_2006.htm

found the google study. see here:

http://labs.google.com/papers/disk_failures.pdf

looks like ~8% each year after year 2.

365 days/year x 24 hours/day= 8760 hours/year. (of *real* world use)

two years = 17,520 hours, which is no where close to manufactures specs of numbers such as "1.2 million hours". it's less than 1.5% of the stated (wishful) number.

if we use 8% per year, we get to 48% at year 6 (roughly speaking), which would be a "mean" (i.e.. 50%).

6 x 8760 = 52,560 hours .. still no where near 1.2 million. see my point? (mtbf specs published by drive manufacturers do not represent real world drive failure statistics .. not even close).

52,560 hours is ~ 4% of 1.2 million.

more: http://www.google.com/search?q=google+hard+drive+failure

Rad, the subject of hard disk reliability is a very complex subject.  (I did see and read the Google research.)

Yes, a warranty period isn’t a perfect indicator of the reliability of the drive, but it should at least be positively and directionally correlated with reliability.

I do agree that MTBF isn’t a perfect measure of reliability.  (A good article on the subject is Mean time between failures.)  Do note that a MTBF of 137 years does not imply that on average a drive will run continuously and properly for over a century (a common misinterpretation of the statistic)!  However, as a metric to compare one hard disk drive (or manufacturer) against another, what is the alternative?

I see your objective in Reply #8, but the math isn’t quite right.  The problem is that the longevity estimate itself varies as a function of time.  For example, you can compute the average lifespan of a population of humans, but it is not the same as computing the projected lifespan of a person given that s/he is now 65 years old.  There is a Bayesian component to the problem.

There are literally an infinite number of ways to measure hard disk drive performance.  Thus, any benchmark study is a sample from that universe and as such is subject to sampling error.  However, again, it worth asking:  what is the alternative?  The benchmarks used by StorageReview appear to have a solid, real-world orientation.  For example, the SR Office DriveMark 2006 benchmark is based on the usage of a mix of commonplace applications, including Microsoft's Office (Word, Excel, Access, Outlook), Internet Explorer, Symantec Antivirus and Winzip.  That sure seems quite an appropriate metric.

In the real world, statistics like the warranty period, MTBF, and independent product reviews and benchmarks are quite valuable, from my perspective.  None of these are without limitations, of course; but, using them results in a reduction of uncertainty in the decision making process that would otherwise be absent.

This is a good discussion.  Please continue to add your perspective!   :)

Quote:

Yes, a warranty period isn’t a perfect indicator of the reliability of the drive, but it should at least be positively and directionally correlated with reliability.

should, yes. but again, i feel warranty can be used more as a marketing tool, than a predictor of reliability.


Quote:

However, as a metric to compare one hard disk drive (or manufacturer) against another, what is the alternative?

We have two options. We can take the word of the drive manufacturers (not optimal in my opinion), or look to real-world metrics, as documented by Google.


Quote:

I see your objective in Reply #8, but the math isn’t quite right.

I was using (admittedly) gross numbers, to illustrate how mtbf stats documented by drive manufacturers are grossly out of touch with reality (which i feel successfully made my point). we could get more accurate numbers, but you're still gonna get nowhere near 1.2 million hours mtbf using google's real-world data. (ps i got an 'A' in Statistics class.)


Quote:

There are literally an infinite number of ways to measure hard disk drive performance

agreed, but no matter how you slice & dice the numbers, you're never going to be able to get the mtbf numbers promoted by drive manufacturers with thiose of real-world users. that was my point.


Quote:

The benchmarks used by StorageReview appear to have a solid, real-world orientation.

No doubt it is, but it's still an artificial benchmark. They're not running those actual program. They're running a benchmarking programs.

There was a flap years back where Intel I believe was tuning the code in their chips to score higher on benchmarks.

This can be done with drives also.

This part of the discussion is moot for me, cuz I've long since moved beyond performance .. to reliablity.. as the most important factor of a hard drive. Tho I do miss with my laptop the responsiveness I had with scsi-based desktop.

My point is that benchmarks are good indicators of perf, tho not chapter and verse as some seem to think. Cuz benchmarks make assumptions about the configurations of the data on your hard drive which may or may not be accurate.

Hey, Rad – good to hear your comments.

The problem with the Google research is that it doesn’t offer reliability numbers by drive manufacture or model – right?  Thus, it is useful at an overall level, but wouldn’t help in evaluating the reliability of one drive versus another.

I absolutely agree that the MTBF numbers are not equivalent to - nor were they ever intended to be - representative of the useful lifetime of a drive.  Many individuals misinterpret the statistic in that way.  Like the duration of the warranty, however, they are suggestive of (but do not conclusively demonstrate) the reliability of the drive.

I don’t know exactly how the SR Office DriveMark 2006 benchmark works, but my reading of the description is that the benchmark is a script that invokes the set of applications to perform predetermined tasks, and the total duration is timed.  Thus, I do believe that the actual applications (e.g., Excel, WinZip, etc.) are in fact launched and run.  It is possible – but highly unlikely – that Western Digital or Seagate cares so much about StorageReview that they would tailor their hardware to artificially inflate their benchmark scores.

A benchmark will not match the actual usage pattern of any individual user, of course.  That, however, is not the intent.  The goal is to provide a standardized metric that reasonably mirrors a real-world usage scenario, so as to permit comparisons among drives.  It is the ability to compare drives that is facilitated by benchmarks, not the ability to predict the performance that a specific user will experience (which is highly dependent on her or his unique usage of the equipment).

I don’t think that reliability and performance are at opposite ends of the same continuum.  You could have low/high reliability crossed with low/high performance in a 2 x 2 matrix, and probably find hard disk drives representative of each quadrant.

P.S.:      Glad to hear you earned an “A” in statistics!  :) That is an essential prerequisite to being a well-educated individual, in my opinion.

yeah, the instructor (stats) suk'ed, too. had to get everything out of the book. got the highest grade in the class (he said).

you're right about lack of drive manufacturer details on the google study. i've always felt seagate makes the most reliable drives on the market .. based on a number of drives i've owned and used.

i had one of those old ibm deathstars, and it never did die on me .. just kept running & running.

It is worthwhile to cross-reference the comments of Nbree:


Quote:

Still, my gut feeling is that SAS and SATA are pretty close to parity right now; SAS has been planned with a lot more headroom, but right now today both interfaces deliver plenty of bandwidth relative to the sustained drive throughputs - the change to PCIe has also leveled things out a bit (compared to recent years with the server-only halfway-house of PCI-X for add-on host controllers).

Source:  http://radified.com/cgi-bin/yabb2/YaBB.pl?num=1174318805

Another source of hard disk drive benchmark data is Tom’s Hardware Guide.

Quote:

i had one of those old IBM Deathstars, and it never did die on me .. just kept running & running.

That was my experience too, and I installed dozens of them.  Then one day while I was typing, like I am now, the drive squalled, balled and screeched to a halt.  When I reached in to remove it, I burned my hand.  It was hot enough to cook my lunch.  That was the last Deathstar drive I ever used.

I now use only Maxtor drives, for their economy and reliability.  (Likewise Seagate drives)
However, I won't even think of installing any HD in my own PC's without a two-fan cooler properly affixed.  Remember....in electronics, "HEAT KILLS".
http://cxt_msp_shafl.members.atlantic.net/CoolDrive.jpg
This photo has been corrected for size.  thank you guys!

Without the 1/4" standoffs, the two fans have nowhere to exhaust their hot air and an Air-Dam results, in which cooling efficiency is seriously inhibited.  With the fans running on the standoffs, proper air flow is assured and the drives always remain at room temperature.  The shock factor of a drive heating up and cooling down just never happens.

People around the world who have tried this technique tell me that they have never had HD's that ran so cool.  The little VIO coolers, only cost me about $4 ea. through a mail-order supplier.  So they are the cheapest Life Insurance I could ever purchase for my drives. ;)

Cheers Mates!
The Doctor  8-)

Another nice fan is the Antec "Spot Cooler" which I found to be very quiet, 3 speed adjustable and about $20.

http://www.antec.com/uk/productDetails.php?ProdID=75018

http://cxt_msp_shafl.members.atlantic.net/CoolDrive.jpg
DrWho2006 -

Howzabout "photoshopping" the image above down to
no wider than 768 pixels MAX.

Your post above requires MAJOR "side-to-side" scrolling
which obscures the really worthwhile message content.

EP :'(

That's interesting > each post has its own set of scroll bars, both up/down and side-to-side. Never saw that before.

here's the cool drive after a little photoshop mojo (45-KB, instead of 150) .. will save bandwidth for those of you still on dial-up.

http://radified.com/gfx/CoolDrive.jpg

better?

The picture of the cooler is good. It explains how the 1/4'' posts provide space for the air to circulate and keep the HD cool. I have ordered the cooling fans and waiting to their arrival. Hopefully it would end the HD failures I have had in the past - anywhere between 1-2 years mean time between failures!!!

*  :)

Rad,
Thank you so very much for the shrink job.  I can't do that here, and have never needed to in the past, as most forum software will "shrink to fit" on any photo posted.
Thanks again.

I received a PM wanting to know what model that cooler is.  I found this number on the box.
HC-350

Let me see if this photo displays any better.
http://i54.photobucket.com/albums/g90/DrWho1943/HardDriveCooler.gif
http://i54.photobucket.com/albums/g90/DrWho1943/HardDriveCooler.gif

I hope that helps someone.  

I ordered that little cooler from here:
http://store.cwc-group.com/hadrcowidufa1.html

The standoffs are the little brass spacers used to mount motherboards.  You'll need spacers with course threads on the male end to match the threads in the holes on the bottom of the HD frame.

Yous guys are the greatest! Thanks again for the help.

Doc  8-)

DrWho2006 wrote on Apr 18^th, 2007 at 11:14am:

"... I ordered that little cooler from here: http://store.cwc-group.com/hadrcowidufa1.html The standoffs are the little brass spacers used to mount motherboards.  You'll need spacers with course threads on the male end to match the threads in the holes on the bottom of the HD frame..."

The link above takes you to SKU: 21515 which is the fan assembly alone.  The link below leads to SKU: 20831 which seems to be the same fan assembly but is packaged as a kit with a set of standoff mounting screws which makes it well worth the difference in price to my way of thinking.  In my case, the difference in unit price was only seventy cents because I ordered more than ten kits as shown in the invoice below :o

As I have stated in the past, I have three married daughters with seven grandchildren scattered across three
states along the Gulf Coast plus neighbors and former coworkers all of whom either received their respective PCs in "trickle-down" fashion from me or otherwise rely on me to provide Symantec software and hardware maintenance.
Those twenty-four HDD coolers will not last much past next Xmas ::)

http://store.cwc-group.com/vioxphadrcow.html

http://img.photobucket.com/albums/v235/El_Pescador/CWCkooler.jpg

EP :'(

El_Pescador wrote on Apr 18^th, 2007 at 10:41pm:

DrWho2006 wrote on Apr 18th, 2007 at 11:14am: "... I ordered that little cooler from here: http://store.cwc-group.com/hadrcowidufa1.html The standoffs are the little brass spacers used to mount motherboards.  You'll need spacers with course threads on the male end to match the threads in the holes on the bottom of the HD frame..." Quote: The link above takes you to SKU: 21515 which is the fan assembly alone.  The link below leads to SKU: 20831 which seems to be the same fan assembly but is packaged as a kit with a set of standoff mounting screws which makes it well worth the difference in price to my way of thinking.  In my case, the difference in unit price was only seventy cents because I ordered more than ten kits as shown in the invoice below :o

It looks like all of them may have the spacers. I too have ordered 8 of them for testing on my systems and did not go for the ball bearing fans. Will provide feedback next week when they should reach me.

Have had HD failures ranging from 1 to 3 years and was frustrating as they failed at the most inconvenient time. Hope the fans fix the problem once and for all.

*  ;D

Using data from the Tom's Hardware Guide website (see Reply #17), I constructed a performance comparison of these two drives:

Western Digital Raptor (WD1500AD)
Interface:  SATA/150
Capacity:  150GB
Cache:  16MB
RPM:  10,000

Seagate Cheetah 15K.5 (ST3300655SS)
Interface:  SAS
Capacity:  300GB
Cache:  16MB
RPM:  15,000

Across a range of benchmarks, the Cheetah outperforms the Raptor by:

Random Access Time:  18%
Average Read Transfer Performance:  46%
Average Write Transfer Performance:  69%
Windows XP Startup Performance:  42%
File Writing Performance:  35%
Workstation I/O Benchmark Pattern:  84%

I must admit:  Rad’s positive comments about the Cheetah certainly appear to be quite well justified.

While the Cheetah is shown underperforming the Raptor on the benchmarks reported on the StorageReview website, this contradictory finding may be due to the fact that StorageReview is basing their numbers on the Ultra 320 (and not the SAS) version of the Cheetah.

Edit:  Information for WD1500AD was corrected (19 APR 2007).

Pleonasm wrote on Apr 19^th, 2007 at 11:45am:

"... Using data from the Tom's Hardware Guide website (see Reply #17), I constructed a performance comparison of these two drives: Western Digital Raptor (WD1500ADFD) Interface:  SATA/150 Capacity:  74GB Cache:  16MB RPM:  10,000..."

http://img.photobucket.com/albums/v235/El_Pescador/PleoRaptor.jpg

El_Pescador, thanks for catching the mistake concerning the WD Raptor capacity.  Reply #27 has been updated accordingly.

Have you now purchased and tested the Raptor?  What is your perspective?

Impressive credentials for the Cheetah . . .


Quote:

The Cheetah 15K.5 is the fastest 3.5” hard drive we’ve ever seen.  Seagate claims up to 125 MB/s transfer rates, which our benchmark results confirm.  We measured 128.6 MB/s as the maximum for sequential reads, which is a world record off the medium.

Source:  The Best in Enterprise Hard Drives (April, 2007)

Pleonasm wrote on Apr 19^th, 2007 at 3:45pm:

"... Have you now purchased and tested the Raptor?  What is your perspective?..."

I do indeed dream about having a pair of Raptor X HDDs.  However, when I awaken I find that I am still living
in a dwelling far from recovered due to Hurricane Katrina.  So, to be quite candid, I must declare that these
Radified Community Forums boards constitute for me a most rewarding diversion and an escape from dreary
reality.  The various computers and gear you have seen mentioned in my posts during the last year or so
belong to friends and relatives who bring them to me for repairs and renovation.  I return them ASAP due
to very limited workbench 'real estate'.

My first-line PCs and most of my ancillary computer gear remain in deep storage.  The only rig I have actually
up and running since the storm is the Dell Dimension 8100 salvaged from the floodwaters and a 19-inch Samsung
CRT monitor that remained safely elevated.  Some of my computer gear, software and peripherals were elevated in advance on makeshift scaffolding that somehow overturned in the floodwaters.  This revolting development was compounded by the fact that we had no flood insurance, and disgustingly the Allstate Premium Homeowners Policy that we had maintained for over thirty years at the same location was rendered impotent because we suffered
no wind and hail damage to the structure itself.

You will know when a degree of 'First-World' America has returned to the stricken coastal areas of Alabama, Mississippi, Louisiana and Texas battered by Hurricanes Katrina and Rita in 2005 whenever the 'crying smiley'
no longer tags along behind my initials.

EP :'(

El_Pescador, best wishes for you and yours to awaken from your 'nightmare' in order to live your dreams.

For those interested in the hard disk cooling fan discussion, the conversation is continued in this thread:  
Hard Disk Cooling Fan.

StorageReview is quite adamant that its benchmarks are valid:


Quote:

If one is to contest the SR Desktop DriveMarks, one must do so on the grounds that the application usage selected for recording is not representative of the majority of users, another topic entirely.  What we would bet, however, is that the majority of diehards who refuse to accept that ATA drives have a place in the world even discounting the cost factor would be hard-pressed to capture a non-multi-user trace that places SCSI drives as head-and-shoulders above ATA drives as they'd like to believe is the case.

Source:  Testbed3: Auditing IPEAK SPT

However, there is sufficient confusion about the benchmarks related to Cheetah drives specifically so as to cause one to pause and at least consider the possibility that these benchmarks are suspicious.

Confusion #1:  Concerning the reported benchmark performance of the Cheetah 15K.5 by StorageReview, note the contradictory information that is provided:  “When testing the previous generation of Seagate's SCSI drives (Savvio 10K.1, Cheetah 10K.7, and Cheetah 15K.5), StorageReview uncovered significant performance differences when these drives were set to different predefined cache segmentation strategies through Seagate's Seatools Enterprise utility.  The Cheetah 15K.5, however, returns the same scores regardless of whether the utility's ‘Performance Mode’ setting is toggled on or off” (see Seagate Cheetah 15K.5).

So, does the Cheetah 15K.5 show “significant performance differences when these drives were set to different predefined cache segmentation strategies” (desktop versus server mode), or does the Cheetah 15K.5 return “the same scores regardless of whether the utility's ‘Performance Mode’ setting is toggled on or off”?   If the latter, then one of two facts must be true: either (1) Seagate - a company known for its technical expertise - isn’t properly optimizing the operation of the firmware for either the server or desktop modes; or (2) the StorageReview benchmarks are not properly reflecting desktop versus server usage pattern differences.

Confusion #2:  The StorageReview benchmark methodology is described in this article:  The 2006 Desktop DriveMarks.  Note especially the graph “Relative Change from 2002 to 2006 DriveMark (Office)” that shows a dramatic decline (-24%) in performance by the Cheetah 15K.4 in desktop mode from 2002 to 2006.  In other words, something about the newer version of the benchmark has had the greatest negative impact upon the Cheetah drive specifically.  If there is that much change in the StorageReview benchmarks when the hardware is constant, can the benchmarks be trusted?

Confusion #3:  Additionally, the graph “StorageReview High-End DriveMark 2006” shows that a Cheetah 15K.4 in desktop mode outperforms a Raptor.

Conclusion:  Thus, I am less than confident in the information reported on the StorageReview website concerning the Cheetah drive.  Using this information to argue against the superiority of SCSI versus SATA (as I did in prior posts) may not be wise.

hi pleo.

excellent research you've done there.

i want to reiterate my point that eugene at sr has long been anti-scsi, and that you have to understand he accepts advertsing dollars from sponsors who sell hard disk drives, which raises questions. or perhaps it's a case of sour grapes. i dunno.

i also want to reiterate that i feel if you were to use a system run by one of these 15K-rpm beasts, your eyebrows would raise.

in all my computing endeavors (and there have been many), i've only had 4 "wow" experiences

1. first 3dfx 3d pci add-on gfx card (playing quake 2 .. the gfx made my eye-balls pop out .. 800x600)
2. adding 2nd 3dfx pci add-on gfx card (in sli configuration .. even better .. 1024x768 rez)
3. first scsi drive (10k-rpm)
4. 2nd scsi drive (15k-rpm)

we can run benchmarks all day long, but a wow is a wow, regardless of what benchmarks say.

ps nice gesture to pesky. well said.

Rad, I think you have summarized the situation well.  I cannot comment upon the “integrity” of the StorageReview benchmarks, but something seems amiss.  What constitutes that “something” will probably remain unknown.

Another consideration, though, is that the hard disk performance information reported by other websites (e.g., Tom’s Hardware Guide) is based upon publicly available benchmarks (e.g., PCMark05) that anyone could use to confirm/refute the assertion.  However, with StorageReview the benchmarks are proprietary and are based upon a “playback of a trace file that captured 30 minutes of typical PC use by yours truly” (i.e., by the StorageReview author in the case of Office DriveMark 2002).  Thus, the StorageReview data is not subject to public scrutiny – an unfortunate condition that lessens its credibility, in my opinion.

Readers of this thread may be interested in the following articles related to benchmarking hard disk drives:

    Lies, Damned Lies and Benchmarks
    A Brief History of the Hard Disk Drive (page 49+)

Concerning the issue of reliability, a study by Carnegie Mellon University of 100,000 hard disk drives over five years found “little difference” in replacement rates between SCSI and SATA drives.

See:  Disk failures in the real world

great links, pleo.

saw this article. thot of you:

http://www.infoworld.com/article/07/05/11/20OPstorinside_1.html


Quote:

Speaking of controversy, disk vendors have been under some criticism lately, mainly about the reliability of disk drives. A study published early this year at FAST (File and Storage Technologies) reached the conclusion that vendor-provided numbers on disk drive reliability could be somewhat inflated. You can find a PDF of the study here.

regarding scsi vs sata, if you think about it, they're saying a drive which spins slower and is slower getting to the data performs better or as good as one that spins faster and jumps on data. common sense should throw up a red flag.

Rad, the study referenced in the InfoWorld article (Reply #39) is the same Carnegie Mellon University research cited in Reply #38.

This research doesn’t say that SATA “performs better or as good as” SCSI (e.g., in terms of sustained transfer rates) – rather, it says that the reliability of the two are essentially the same.  Somewhat counterintuitive, yes; but, data are data, no?

I was talking about SR when I mentioned performance. Shoulda been more clear.

As we mentioned, "data are data" comes from (artificial) benchmarks and I think you'd find 15K-rpm SCSI "feels" faster .. given two otherwise identical systems.

By "SR," I think you were referencing the StorageReview website benchmarks.  In contrast, the Carnegie Mellon University research doesn't assert the claim that SATA is faster than SCSI (or the opposite); rather, it makes the observation that the reliability of SATA and SCSI hard disk drives are about the same.  In other words, this research is not about performance – but about reliability (i.e., the inverse of failure).

Additionally, the Carnegie Mellon University research does not involve "benchmark" comparisons.  They are based upon tabulations of the failure rate of 100,000 actual hard disk drives in use.

I do agree, though, that a 15K SCSI hard disk drive will – under most circumstances – outperform a 10K SCSI or a 10K SATA hard disk drive, although the latter two appear to have nearly the same performance characteristics, as far as I can determine, in a non-server environment.  Is that your understanding, too?

yeah.

i have no hard data in front of me, but from past experience & research, i'd expect the 10K SCSI to have the edge in server-use, with 10K SATA having the edge in desktop systems, .. due to cache that's optimized for desktop apps.

my friends, who i visited on cinco de mayo have a 15K SCSI-based system, which I built for them (specifically to edit video with Avid Xpress Pro + Mojo hardware acceleration).

Even tho the system is now 4 years old, every time I get on it, I *still* get a little "wow'ed" by how RERSPONSIVE it is. Then I remember the SCSI boot/system drive.

I feel that, even tho 10K SATA drives may "perform" well, they still aren't gonna have that level of *responsiveness* that is available with a 15K-rpm SCSI boot/system drive.

http://blogs.radified.com/2007/05/cinco_de_mayo_laguna_beach.html

did you notice new rad server is running scsi raid?

http://blogs.radified.com/2007/05/website_move_new_server_mysql.html

Concerning the 10K SATA versus 10K SCSI comparison, the manufacturer specifications of the Western Digital Raptor (WD1500AD) versus the Seagate Cheetah 10K.7 (ST3146707) support both of our perspectives:

Average latency (msec):  Raptor=3.0, Cheetah=3.0
Random read seek time (msec):  Raptor=4.6, Cheetah=4.7
Random write seek time (msec):  Raptor=5.2, Cheetah=5.3

Note that the Raptor is slightly faster than the Cheetah for read/write seek times, but on balance they are "the same."

yeah, i *did* notice.

seek times aere largely a function of actuators.

bigger actuators can move the read/write heads around faster. (tho noisier)

they must be equipping those raptors with SCSI-grade actuators.