Wich conection is not bottleneck by HDD speed?

[leandrodafontoura]

Here's for the experts. Im trying to learn more about external HDD technology. Ok, as far as I know:

USB 2.0 = 480MB/s
Firewire 800 = 800MB/s
esata = 1,5GB/s
USB 3.0 = 5GB/s
Thunderbolt = 10GB/s (if Im not mistaken, this is the speed of Pci-e x4, wich happens to be revodrive speeds)

I been reading all my life that HDDs, even 10000RPM, cannot achieve sata I/esata speeds of 1,5GBs because of hardware mechanics limitation. The speed wich data is writen/read by the drive is slower that the speed the cable could provide.

Well, wich speed is that exactly? Where would 5400RPM, 7200RPM or 10000RPM fit in the chart above? Closer to Firewire 800 or esata? What if the drives are in a RAID 0 enclosure, like My Studio from WD? Btw, SSDs achieve wich speed? Ive seen thunderbolt SSDs by lacie, as well as Revodrives by OCZ. Ok, so Im putting below some links to products for example, as well as re-asking the questions above in a more fashionable manner:

1) 5400RPM external drives, closer to Firewire 800 or esata? Perhaps, is Firewire 800 more than enough already? Or will I get speed increase by going USB 3.0?

http://www.bhphotovideo.com/c/product/772995-REG/G_Technology_0G01993_G_DRIVE_mobile_USB_Hard.html

http://www.bhphotovideo.com/c/product/753095-REG/Western_Digital_WDBACX0010BBL_NESN_1TB_My_Passport_Essential.html

2) 7200RPM external drives, closer to firewire 800 or esata?

http://www.bhphotovideo.com/c/product/642733-REG/G_Technology_GD4_1000_1TB_G_Drive_External_Hard.html

http://www.bhphotovideo.com/c/product/755381-REG/Iomega_35182_2TB_Prestige_Desktop_External.html


3) 5400 RPM drives in RAID 0 (2x), closer to firewire 800, esata or USB 3.0 or Thunderbolt?

http://www.bhphotovideo.com/c/product/824996-REG/LaCie_9000107_2TB_Little_Big_Disk.html


4) 7200 RPM drives in RAID 0 (2x), closer to firewire 800, esata or USB 3.0 or Thunderbolt?

http://www.bhphotovideo.com/c/product/552322-REG/Western_Digital_WDH2Q20000N_2TB_My_Book_Studio.html



5)7200RPM drives in RAID 0 (4x), closer to esata, USB 3.0 or thunderbolt?

http://www.bhphotovideo.com/c/product/753279-REG/LaCie_301562U_12TB_4big_Quadra_External.html

6)SSDs drives in RAID 0 (2x), closer to esata, USB 3.0 or thunderbolt?

http://www.bhphotovideo.com/c/product/824998-REG/LaCie_9000108_240GB_Little_Big_Disk.html



Please, note that Im not looking for advice on wich product to buy, Im simply trying to learn more about the different technologies.

 

[buzznut]

So transfer rates are very drive specific, and there are a number of other variables that determine overall drive speed. various read and write rates for example.

But lets address transfer rates as this is what you're really looking for.
1) Some 5400 rpm drives can transfer just as fast as 7200 drives. Lets call them equal for this discussion. Max transfer rates would be faster than USB 2.0, probably firewire is fast enough but eSATA would be best.
2) eSATA
3) Not close to SATA III. In the case of a SAS array, I would grab the highest transfer capability however. Sometimes burst transfers can get pretty high. USB 3.0 is almost the same as SATA III, but there are still not a lot of USB 3.0 devices, and they are still pricey. eSATA or SATA III.
4) Same thing. Raid 0 is not useful usually for external drives as they are mostly used for backup. RAID 0 is NOT safe for backups. But still, I would say SATA III is the best conneciton.
5) Again, this is not a good purpose for SSDs as real estate is limited. The OCZ Vertex III can hit 550MBps, and so it is capable of filling the SATA III pipeline, it may be somewhat limited by USB 3.0. Raid 0 then would be closer to the Thunderbolt spec you mentioned, at least theoretically. Of course there's no way to test this now. So raid 0 on SSD drives does not have a viable external pathway, unless you could raid across two eSATA III ports. Thus we have the revo drive, which uses the PCI express bus to acheive much higher transfer rates for raided SSDs.