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What am I doing wrong ??? Or is Adaptec 21610SA just a crappy RAID card ?



 
 
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  #21  
Old November 30th 04, 09:03 AM
Toomas Soome
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Tim Boyer wrote:
=20
In about six months, I'm going to be in the market for a 2TB system, an=

d will
have to make some of the same choices. Rita, _why_ is SCSI so much bet=

ter than
SATA?


current data transfer rates (lets not argue about possible future=20
numbers, I have some but never done research for them):

SATA: 150Mb/s (up to 1.5Gb/s?)
SCSI: 320Mb/s
SAS: 3Gb/s (roadmap up to 12Gb/s)?
FC-AL: 2Gb/s (roadmap up to 10Gb/s ?)

reliability:
SCSI MTBF 1,200,000 hours, many SATA drives only run to 600,000 MTBF=20
(http://searchstorage.techtarget.com/...,sid5_gci1001=
942_tax294586,00.html)

and some real numbers as well regarding to reliability:

Deskstar 7K400, http://www.hitachigst.com/hdd/support/7k400/7k400.htm
Error rate (non-recoverable) 1 in 10E14 =09
Start/stops (at 40=B0 C) 50,000

Ultrastar 15K147 http://www.hitachigst.com/hdd/support/15k147/15k147.htm
Error rate (non-recoverable) 1 in 10E15 =09
Start/stops (at 40=B0 C) 50,000

in general, SATA will not replace SCSI anytime "soon", high end SCSI=20
will still outperform SATA in many terms... but SATA does definitely=20
have it's place as well.

toomas
--=20
Kissing a smoker is like licking an ashtray.
  #22  
Old November 30th 04, 01:19 PM
Tim Boyer
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On Tue, 30 Nov 2004 10:03:46 +0200, Toomas Soome
wrote:

Tim Boyer wrote:

In about six months, I'm going to be in the market for a 2TB system, and will
have to make some of the same choices. Rita, _why_ is SCSI so much better than
SATA?


current data transfer rates (lets not argue about possible future
numbers, I have some but never done research for them):

SATA: 150Mb/s (up to 1.5Gb/s?)
SCSI: 320Mb/s
SAS: 3Gb/s (roadmap up to 12Gb/s)?
FC-AL: 2Gb/s (roadmap up to 10Gb/s ?)

reliability:
SCSI MTBF 1,200,000 hours, many SATA drives only run to 600,000 MTBF
(http://searchstorage.techtarget.com/...294586,00.html)

and some real numbers as well regarding to reliability:

Deskstar 7K400, http://www.hitachigst.com/hdd/support/7k400/7k400.htm
Error rate (non-recoverable) 1 in 10E14
Start/stops (at 40° C) 50,000

Ultrastar 15K147 http://www.hitachigst.com/hdd/support/15k147/15k147.htm
Error rate (non-recoverable) 1 in 10E15
Start/stops (at 40° C) 50,000

in general, SATA will not replace SCSI anytime "soon", high end SCSI
will still outperform SATA in many terms... but SATA does definitely
have it's place as well.

toomas


Thanks much, Toomas! I'm replacing a _very_ old Clariion, fairly lightly used,
so anything's gonna be an improvement. But I value reliability over
performance, and it looks like I'd be smart to stick with SCSI - for now, at
least.


--
tim boyer

  #23  
Old November 30th 04, 04:35 PM
J. Clarke
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Default

Toomas Soome wrote:

Tim Boyer wrote:

In about six months, I'm going to be in the market for a 2TB system, and
will
have to make some of the same choices. Rita, _why_ is SCSI so much
better than SATA?


current data transfer rates (lets not argue about possible future
numbers, I have some but never done research for them):

SATA: 150Mb/s (up to 1.5Gb/s?)


No. 150 M_B_/sec. 3 Gb/sec hardware is shipping, not that it has any
real-world relevance. All allocated to a single device. No drive on the
market, SCSI or SATA, is capable of sustained transfers at anything close
to this rate, so it's adequate for any purpose.

SCSI: 320Mb/s


Shared among up to 15 devices. No clear advantage to SCSI here unless you
give each device a separate channel, which gets hugely expensive very
quickly.

SAS: 3Gb/s (roadmap up to 12Gb/s)?


Again, though, shared. And you're interchanging bits and bytes. That's
about 300 MB/sec.

FC-AL: 2Gb/s (roadmap up to 10Gb/s ?)


Again, shared. And that's roughly 200 MB/sec when you allow for overhead.

reliability:
SCSI MTBF 1,200,000 hours, many SATA drives only run to 600,000 MTBF


This has nothing to do with SATA vs SCSI--look up the specs on WD Raptors
and you'll find that same 1,200,000 MTBF. If you want enterprise-class
storage get enterprise-class storage.

(http://searchstorage.techtarget.com/...294586,00.html)

and some real numbers as well regarding to reliability:

Deskstar 7K400, http://www.hitachigst.com/hdd/support/7k400/7k400.htm
Error rate (non-recoverable) 1 in 10E14
Start/stops (at 40° C) 50,000

Ultrastar 15K147 http://www.hitachigst.com/hdd/support/15k147/15k147.htm
Error rate (non-recoverable) 1 in 10E15
Start/stops (at 40° C) 50,000


And if you look at the Raptor you'll find again 1 in 10E15.

in general, SATA will not replace SCSI anytime "soon", high end SCSI
will still outperform SATA in many terms... but SATA does definitely
have it's place as well.


While this is true, it is not for any of the reasons you stated. SCSI does
have a few real advantages--there's a lot more in the way of
enterprise-class host adapters and array cabinets and the like available
for one thing. For another it allows _much_ longer cables. For a third,
for now the fastest SATA drives do not match the speed or capacity of the
fastest SCSI drives, and for 10K RPM SATA drives there's no second
source--that last is a marketing issue, not a technical one--there's no
reason that 15K RPM SATA drives can't be produced by multiple vendors, it's
just that so far they've decided not to.

Further, it's all rather far afield as the problem the OP is describing
isn't really addressed by any of this. His basic problem remains that he
got a substandard array controller.

toomas


--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
  #24  
Old November 30th 04, 04:57 PM
Anton Rang
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"news.tele.dk" writes:
So what youre saying is: "The speed of SCSI disks is more than 6 times that
of SATA".


You're being overcharged for the SCSI disks....

But there are significant differences between SCSI and SATA in both
performance and reliability. They're not intrinsic to the interface,
rather to the cost structure of each.

SATA disks typically have less error checking internally than SCSI,
increasing the likelihood of undetected errors. Not a big deal if
you're working with 1 disk; more serious when you have 10 and
mission-critical data.

Some SATA disks don't have enough RAM to store the whole sector flaw
map at once. Random access across those disks can waste a whole
(extra) disk rotation to read the flaw map for a track. The drive
will cache some of these, and this works fine for home use, but in a
database environment this can be a 2x performance hit.

SCSI and FibreChannel disks, at this point, are engineered for
reliability, because the market buying them are customers who care
about that. SATA is engineered for low cost, period.

Anton
  #25  
Old November 30th 04, 05:19 PM
Marcin Dobrucki
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Default

Rita Ä Berkowitz wrote:

Tim, not knowing exactly what your requirements are, I'll just repeat in the
simplest terms what I said in a previous post, "When you factor in ease of
deployment, reliability, longevity, and performance you quickly realize it
pays for itself in short order." That said, depending on your requirements
SATA might be better for you if you have minimal demands and expectations.


Sorry, a question from a lurker. How does the SCSI interface improve
reliability of the disks? We are replacing SCSI disks by the dozen.
The only thing that I can think of here is that someone is using
home-grade SATA drives in enterprise environment.

The only reason I don't see more SATA disks being deployed locally is
that they usually are running at 7200rpm and not 10000 or 15000 like the
new scsi stuff, and hence access times are longer. This carries some
performance penalty for our systems indeed. But ease of deployment is
hardly an issue as the disks are hot-plugable, disk hardware fails
regardless of interface type, and frankly.. scsi prices are ridiculous.

/Marcin
  #26  
Old November 30th 04, 05:32 PM
Marcin Dobrucki
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Toomas Soome wrote:

reliability:
SCSI MTBF 1,200,000 hours, many SATA drives only run to 600,000 MTBF
(http://searchstorage.techtarget.com/...294586,00.html)


www.google.com - "enterprise sata mtbf" -- first match

http://www.wdc.com/en/products/curre...wd740gdrtl.asp

== MTBF=1'200'000 hours

Lets not compare disks aimed at desktop market, and enterprise grade
hardware.

/Marcin
  #27  
Old November 30th 04, 05:44 PM
Peter
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No. 150 M_B_/sec. 3 Gb/sec hardware is shipping, not that it has any
real-world relevance. All allocated to a single device. No drive on the
market, SCSI or SATA, is capable of sustained transfers at anything close
to this rate, so it's adequate for any purpose.


Not true:
http://www.fcpa.com/products/hard-dr...fications.html
Data transfer rate To/from media 147 MB/s

SCSI: 320Mb/s


Shared among up to 15 devices. No clear advantage to SCSI here unless you
give each device a separate channel, which gets hugely expensive very
quickly.


Perfomance issues rarely relate to a sequential read/write speed alone. Most
likely they reflect poor random IO operations. Putting interface maximum
speed at the first place, is a mistake.



  #28  
Old November 30th 04, 05:58 PM
Nik Simpson
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Marcin Dobrucki wrote:
Rita Ä Berkowitz wrote:

Tim, not knowing exactly what your requirements are, I'll just
repeat in the simplest terms what I said in a previous post, "When
you factor in ease of deployment, reliability, longevity, and
performance you quickly realize it pays for itself in short order." That
said, depending on your requirements SATA might be better for
you if you have minimal demands and expectations.


Sorry, a question from a lurker. How does the SCSI interface
improve reliability of the disks?



The SCSI interface per-se doesn't, but because SCSI & FC drives are designed
for "enterprise class" applications they go through a different & more
rigourous quality control process than consumer drives. It's this more
comprehensive QC that is responsible for better reliability rather than the
interface. So in the future there is no technical reason why the SATA drives
cannot meet the same reliability leves as SCSI, but in doing so they would
have to adopt the same QC & testing procedures which would erode the price
difference between them and other more "reliable" types of drive.


--
Nik Simpson


  #29  
Old November 30th 04, 06:18 PM
Peter
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Default

No. 150 M_B_/sec. 3 Gb/sec hardware is shipping, not that it has any
real-world relevance. All allocated to a single device. No drive on the
market, SCSI or SATA, is capable of sustained transfers at anything close
to this rate, so it's adequate for any purpose.


Not true:
http://www.fcpa.com/products/hard-dr...fications.html
Data transfer rate To/from media 147 MB/s

SCSI: 320Mb/s


Shared among up to 15 devices. No clear advantage to SCSI here unless you
give each device a separate channel, which gets hugely expensive very
quickly.


Perfomance issues rarely relate to a sequential read/write speed alone. Most
likely they reflect poor random IO operations. Putting interface maximum
speed at the first place, is a mistake.




  #30  
Old November 30th 04, 06:58 PM
Anton Rang
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Default

"Peter" writes:
real-world relevance. All allocated to a single device. No drive on the
market, SCSI or SATA, is capable of sustained transfers at anything close
to this rate, so it's adequate for any purpose.


Not true:
http://www.fcpa.com/products/hard-dr...fications.html
Data transfer rate To/from media 147 MB/s


He said *sustained* data rates. You only get 147 MB/sec while you're on one
track. As soon as you have to switch heads or seek, there's a gap in the data
stream.

The only benchmark I could find on that drive in a couple of minutes
of hunting shows 80 MB/sec, which is still very good.

http://neasia.nikkeibp.com/wcs/leaf/...sabt/fw/323039

-- Anton
 




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