I was offered a couple of shelves (shelf's) of 500G drives (probably 16 per shelf?). But, they're all marked "12V only".
I'm *guessing* this means they only draw power off the 12V supply (probably with a 5V regulator onboard to handle the logic).
If that's the case, as long as the 12V supply in my devices is capable of handling the additional power that the 5V supply would otherwise deliver to the drive, there should be no problem, right?
But, I'm leary of just trying one -- of concern as to whether there isn't some other, more insidious, consequence that could eat some of my kit!
I've sent an email asking for P/N's so that might shed more light. But, maybe someone here has firsthand experience with their ilk?
Exactly. Which begs the question: why deliberately and PROMINENTLY mark the drives as "12V ONLY"? How is that any difference than leaving *no* special marking on it and specifying "0 mA" as the 5VC power requirement? Even if there is some extra power reflected to the 12V supply due to the needs of the 5V logic on the drive (perhaps it's 3V logic!)
My fear is they may be "special" drives that just happen to look like FCAL drives and only intended to work in this particular model shelf.
Or, perhaps the warning is to note that you can't even *talk* to the drive unless the 12V supply is up?
I'll have to wait for a model number to see if they're even "COTS" drives or some other OEM-special.
I'd guess (because I haven't seen this before) that the marking is so you don't put them in (say) an external enclosure with a 5V-only power supply or attempt to power them directly from a USB port. I did a bit of checking around, and it seems that things have changed a bit from the old ST506/IDE days -- there are 5V-only HDDs now.
In any case, if the drive is from one of The Usual Suspects (seagate, Hitachi, etc.) and has standard connectors, I'd expect that the worst that could happen would be if you tried to run it from a connector that didn't supply sufficient 12V power would be that it wouldn't spin up.
Frank McKenney
--
...[T]he people know in their hearts that journalism is a conventional
art like any other, that it selects, heightens, and falsifies. Only
its Nemesis is the same as that of other arts; if it loses all care
for truth it loses all form likewise. The modern who paints too
cleverly produces a picture of a cow which might be the earthquake at
San Francisco. And the journalist who reports a speech too cleverly
makes it mean nothing at all.
-- G.K. Chesterton / On the Cryptic and the Elliptic (1908)
Laptop (2.5") drives from the IDE/PATA days are 5V-only powered. Even SCSI laptop drives were powered from 5V. Mostly, SSDs are in 2.5" form, and also 5V-only powered, though there may be some 3.3V options as well.
They're FCAL drives. IME, I've never seen an external enclosure (other than a shelf) that would accept anything of the sort! :> )
But, there's be no need for such a BOLD warning! You'd note the power requirements for each of the supplies (often printed right *on* the drive) and determine if your system could deliver the required power (taking into account all loads, etc.).
Again, FCAL drives so you're not dealing with consumers but, rather, guys who run server farms. (I don't expect consumers to have a *clue* as to what sort of power they have "available" in their boxen -- even consumers who "should know").
Considering the type of kit for which they are intended *and* the type of folks who'd be responsible for maintaining that kit, I have to regard this as a warning, of some sort. E.g., you wouldn't care if it was a "5V only" device (e.g., SSD) -- as long as the power consumed wasn't hellacious (compared to the electromechanical disk that it replaced). You see SATA drives that don't use all three of the supplies present on that connector -- yet, you don't see a prominent warning to that effect.
This suggests there is something nonstandard about the i/f. There's nothing apparent in a "normal" SCA2 interface that suggests the reliance on *just* the 12V supply would compromise the drive's operation. (e.g., I could see if the interface sensed a load on the 5V line to implement "drive present" but that's already explicitly covered in the i/f spec).
But, I could be looking at this all wrong: perhaps the interface to which it is intended to alert the user is the interface in the device into which the drive mates! I.e., perhaps *that* device isn't a standard SCA2 i/f and doesn't *supply* 5V on the specified pins! That would make sense for a large shelf (don't include a 5V power supply in the "system"; just deliver a robust 12VDC and count on the *special* drives to Do The Right Thing).
So, in effect, the "12V ONLY" label isn't a warning but, rather, a
*permission*! I.e., "this drive WILL work in that piece of kit that ONLY supplies 12VDC -- instead of 12V *and* 5V". As such, anyone trying to install a drive that *isn't* marked as such -- i.e., that *requires* the presence of 5V for the drive to operate -- will encounter a problem!
As such, maybe I need to know more about the *shelf* instead of the *drive*!
But they could have just as easily powered 3.3V logic with an LDO on the 5V supply. I.e., what are they saving (a pin on a connector?)
The question then is: why make such a prominent notice about this? Most drives have a boatload of information on the label. Determining drive *capacity* is usually an exercise like "Where's Waldo" (you would think capacity would be prominently marked).
Yet, this "warning" stands out at more than arm's length!
(OTOH, I'm told it doesn't say "WARNING: 12V ONLY" but just "12V ONLY".)
See my comments to Frank. I suspect the "problem" lies more in the system to which the drives are intended to mate. I.e., that a "normal" (non-12V only) drive wouldn't work in that particular system. They'd be missing this "feature".
If that's the case, I should have no problems with them, here. (subject to any additional loading on the 12V supply)
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