Finally, those SCSI/SATA performance numbers.

Comparing yesterday's "primary storage" with today's Serial ATA I know, I'm months and months late providing this data, but here it is... The point here is that the SATA drives on the market today perform as well as the SCSI...

December 6, 2004

2 Min Read
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Comparing yesterday's "primary storage" with today's Serial ATA


I know, I'm months and months late providing this data, but here it is...

The point here is that the SATA drives on the market today perform as well as the SCSI drives that we were

sold 5 years ago for "core data center" use. Granted data usage has changed, but enough that yesterday's

main storage standards aren't good enough for primary storage today? Take a look at the numbers culled

from the manufacturer's own data sheets, and you decide.

So where this data comes from. I took the data sheets for the drives named, found key performance

information, and compared them. The SCSI drives are older (3-5 years ago) models that were sold as "data

center storage" at the time they were popular, and the S-ATA drives are new today. Some vendors in the

storage industry want to tell you that Serial ATA is inferior by definition, these numbers should show you

that is just not true as a valid blanket statement. They are lower performance than SCSI drives

available today, but the numbers show they are data center/primary storage quality. Only in MTBF (for

Seagate) did we see a significant difference that was not in the Serial ATA drive's favor. In fact, the

only major difference in SCSI's favor seems to be years of warranty.



As always, I have to say that there are some applications that benefit from the performance and added

management functionality of newer SCSI drives, but for most applications, Serial ATA is good enough, particularly when combined with RAID 5.

Maxtor/Quantum:

Atlas II 4.5 GB SCSI

Maxline III SATA

Seek Time (Avg Read)

8 ms

9.3 ms

RPMs

7200

7200

Transfer Rate

40 MB per second

150 MB per second

Buffer size

512 KB

16 MB


* Interestingly, the data sheet did not have MTBF values for the Atlas II.

Western Digital

Vantage 9 GB SCSI

Raptor 36.7 GB SATA

Seek Time (Avg Read)

6.6 ms

5.2 ms

RPMs

10000

10000

Transfer Rate (buffer to host)

80 MB per second

150 MB per second

Buffer size

2 MB

8 MB

MTBF

1,200,000

1,200,000



Seagate

Barracuda 180 GB SCSI

Barracuda 200 GB SATA

Seek Time (Avg Read)

7.6 ms

8.5 ms

RPMs

7200

7200

Transfer Rate (to-from disk)

36.1 MB per second

58 MB per second

Buffer size

4-16 MB

2-8 MB

MTBF

1,200,000

600,000

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