SATA power.... a quickie question

[nd4spdbh2]

OK well today i was lookin at my friends psu and i noticed that he had sata power connectors that had, Ground, 12v, 5v, and 3.3v.... then i got home today and realized that my sata drives were using 4pin molex to sata power with only, Gound, 12v and 5v... what is the 3.3v for? its obvious that the hds dont need it but what in the world is it for?

[.sentinel]

1 V33 3.3v Power
2 V33 3.3v Power
3 V33 3.3v Power, Pre-charge, 2nd mate
4 Ground 1st Mate
5 Ground 2nd Mate
6 Ground 3rd Mate
7 V5 5v Power, pre-charge, 2nd mate
8 V5 5v Power
9 V5 5v Power
10 Ground 2nd Mate
11 Reserved -
12 Ground 1st Mate
13 V12 12v Power, Pre-charge, 2nd mate
14 V12 12v Power
15 V12 12v Power

I am almost guessing that the 3.3V is for standyby? or staggered startup?

[Snugglebear]

It was put there just in case it was ever required. The SATA connectors are meant to be everything to everybody - servicing desktops to servers (via SAS) to laptops and embedded devices. While no drives currently use the 3.3v line, it's entirely possible that some ultra-portable machines will require even lower-power drives in the future.

[nd4spdbh2]

ya i have no clue...

Hey i just setup a raid setup with 2 80gb SATA 7200.7 Seagates and i was wondering if these numbers were good...

150MBps burst
90MBps average read...

i can tell you its a **** load better that whats in my comp right now of 90MBps burst and a 50MBps read.

But i was hopin for closer to a doubling... seems as how the numbers for 1 of thoes drives in raid is 99MBps burst and 47MBps read.

[hotrod469]

I get about 95 to 96MBps average read in HDtack 3 with my 2 seagates. It has gone as low as 91MBps. Hope this helps a little.

[Snugglebear]

RAID0 does not provide a doubling of performance. There is sufficient overhead involved to eliminate some gains, and another fair chunk is removed due to the drives operating asynchronously. In the PATA days RAID0 could usually provide 150% of single drive performance, but since then things have improved (more intelligence on the controllers along with increased drive capabilities - took mfgs a long time to test their firmware in RAID configs and ensure that they weren't screwing it all up with certain assumptions). The only thing that looks bad with what you're posting is the burst speed, though in all honesty it's nothing to worry about since it doesn't have that much of an impact on performance.

And before I forget again, it occurred to me after posting a few minutes ago that the electronics on drive units run off 3.3v supplies. At present they step down the 5v line to 3.3v, so at some point in the future manufacturers may get around to using the native 3.3v line and be able to remove the extra mosfets.

[nd4spdbh2]

ya i thought they stepped it down or what not... as for the drives i have a friend with 2 PATA ATA 100 drives in raid 0 that get about the same specs as my single drive but alot better specs in Raid 0 his are like 180MBps burst 100MBps avg read. and his drives are using converters... mabey its just the drives... seagates havnt been known to be the fastest, but they sure are reliable.