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SCSI vs SATA

griessh
griessh asked
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Last Modified: 2012-08-13
I have to replace a system that uses a 10,000 RPM Ultra320 SCSI HDD with a system that has a 7200RPM SATA HDD with DataBurst Cache for a high volume/throughput database application.

Does anybody know a way to compare those two disks? Is the SATA drive a reasonable replacement in matters of throughput?

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Werner
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These tests may interest you greissh:
http://www.barefeats.com/fire36b.html
http://www.barefeats.com/hard35.html

Agreed droswell SCSI are more reliable, faster for random seek ie database work, it can burst and sustain data thru at higher rates and it utilises the CPU much better, it's hot swappable and it will allegedly make your coffee for you too -  For business fileserver its a great call.

As a poor impoverished PC User I go for Inexpensive Disks, hey I could make an Array out of them :-)

Peace
I do agree with the above.

But Western Digital is trying to mesh the difference between SATA and SCSI.  Not only for speed but reliablity.  The WD Raptor 36 and 76 GB drives are doing this.  The speed is still slower than SCSI, but has a comparitive 5 year warrenty.  
Does this mean we are friends again?
andyaldersaggar maker's framemaker
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Commented:
Throughput in MB/s is not much use in a database environment, since it is random I/O it is the number of I/O operations per second that matters and the major factor there is the spin speed. Head positioning is about the same for SATA and SCSI since the machanics are similar. Bus transfer speed isn't very important since it is swamped by the mechanical latency.

Cache may help but you have to consider what happens if the machine crashes. If disk write cache is enabled (and it is enabled for most benchmarks) then when you reboot the data may become corrupt since as far as the DB is concerned the data has been written to the platter where infact it got lost. Same goes for controller caching unless it is battery backed.
Hippy
are you talking to me?

Commented:
However, random IO is heavily influenced by your seek time.  
So a 15K rpm SCSI drive with these specs:
Single Track0.4 ms
Average 3.8 ms
Full-Stroke 8.0 ms
 
But a WD SATA drive
Read Seek Time (Average)  8.9 ms  
Write Seek Time (Average)  10.9 ms (average)  
Track-To-Track Seek Time  2.0 ms (average)  
Full Stroke Seek  21.0 ms (average)


Author

Commented:
Thanks

That was the info I looked for and the link helped, too. Appreciate your help!

=====
Werner
andyaldersaggar maker's framemaker
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Distinguished Expert 2019

Commented:
Indeed. but it isn't about SCSI Vs sATA, it's about how fast the platter spins. if you compare a 7200K SCSI and sATA drive from the same manufacturer there isn't much difference since it is the same mechanical HDA with different logic board.
Droswell

you might want to look at the seek times of the Raptor drives.  They are as fast as some older SCSI drives.

Author

Commented:
THANK YOU! MY QUESTION WAS ANSWERED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
no yelling.  It will be just fine.  People are allowed to post after your question is answered.  

Author

Commented:
Listen, I appreciate your comments very much, even after I closed the question. But do you know what this question was all about? I asked about two pretty specific types of HDs.

YOU make it now a discussion about WD and Raptor drives, you want to make it your discussion about YOUR topic. That's what I'd like to stop. This is not a public HD speek/seek time area, but please feel free to start your own thread.

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Werner

Commented:
just quit reading them...

Commented:
I think we are paying for this... you know?  I get his drift.
andyaldersaggar maker's framemaker
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Distinguished Expert 2019

Commented:
Please don't post in questions that have been closed 3 years ago.
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