[Cialug] SATA v. SCSI

[Nathan C. Smith]

Wow, thanks for the great write-up, that's very re-affirming. 

I have a PIII 900 Mhz as my main workstation at work and the SCSI drive is
probably what keeps it usable/tolerable.

Those new Sun SAS drives look scary.  Or maybe I mean dainty - if I am
thinking of the right ones.

I've also noticed there are some "special" SATA drives designated for use in
server or RAID applications.  They come at a premium price.  I'm not sure
how they differ from standard consumer drives, if at all.

-Nate

> -----Original Message-----
> From: Randy Rote [mailto:randy.rote at gmail.com] 
> Sent: Thursday, May 11, 2006 9:53 PM
> To: Central Iowa Linux Users Group
> Subject: Re: [Cialug] SATA v. SCSI
> 
> 300 MB/s is the rated speed of the SATA II bus and 320 MB/s 
> is the speed of the
> Ultra 320 SCSI bus.   I'm sure you could get a drive to do 
> small burst transfers
> from cache at this speed, but the sustained rate of the top 
> end drives is just shy of 100 MB/s right now.
> 
> SCSI is still king of the hill in terms of absolute maximum 
> throughput and latency.  A lot of this advantage comes with 
> the 15K rpm speeds.  However, the performance comes at a 
> price. SATA drives give you more capacity per dollar, with 
> roughly twice the average access time.
> 
> Storage Review has some great reading material on this subject.
> 
>   Performance comparisons:  
> http://www.storagereview.com/comparison.html
> 
>   Reference Guide:
> http://www.storagereview.com/guide2000/ref/hdd/perf/perf/spec/
> trans.html
> 
> Western Digital has a white paper on the topic.  This is a 
> marketing tool though, so it should be taken with a grain of 
> salt, but it's a great overview.
> http://westerndigital.com/en/library/sata/2579-001097.pdf  __(PDF)__
> 
> Some digging through google also turned up a related 
> discussion on Slashdot.
> http://ask.slashdot.org/article.pl?sid=06/01/24/2332240
> 
> 
> Bottom line though, it depends on your application.  If 
> you're running a server that needs to grab data from all over 
> the disk in little chunks, scsi is probably the best fit.  
> For larger sustained transfers, the SATA compares pretty 
> favorably.  If you're on a budget and need to maximize 
> capacity, SATA is the way to go.  For most cases, the extra 
> cost of the SCSI drives probably isn't worth it.  A lot of 
> enterprise level vendors are shipping serial interface drives 
> with new systems.  Sun's new servers, both the AMD Opteron 
> and UltraSPARC T1 systems are shipping with SAS drives now.  
> Western Digital has made it seemingly impossible to purchase 
> a new SCSI drive. Maybe I'm not looking hard enough.
> 
> As far as reliability, SATA II drives haven't really been 
> around long enough (mid 2004 I think) to get a good feel for 
> long-term reliability yet.  Most are probably still under 
> warranty.  Your best bet would be to stick with vendors 
> offering 5 year warranties on their drives. If they're 
> offering a guarantee, it's a safe bet that they're sure the 
> drive will last at least that long.
> 
> --
> Randy Rote
> Simon Tire & Cellular -- Information Systems Specialist
> Phone: 515.282.0205
> 
> Nathan C. Smith wrote:
> > I've seen SATA and SCSI drives (ultra SCSI) list speeds of 
> 300Mb/s.  
> > Is this the raw transfer speed of the interface or the 
> speed from disk 
> > to bus or is that the hidden marketing element in these 
> advertised speeds?
> > 
> > It boils down to this:  assuming you have a good SATA 
> controller or a 
> > good SCSI controller, are the disk subsystems going to be 
> on par with each other?
> > Can SATA be seriously considered as a replacement for SCSI yet?
> > 
> > -Nate
> > 
> > Nathan Smith  McKee, Voorhees & Sease, P.L.C.  515.288.3667 
> > _______________________________________________
> > Cialug mailing list
> > Cialug at cialug.org
> > http://cialug.org/mailman/listinfo/cialug
> > 
> 
> 
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