Pi lightweight server with USB SSD instead of powered HDD?

As it happens, I'm going to try it with a 2B because I have a spare one lying around. But the documentation shows the same 1.2A max total USB draw for 2B, 3B, 3B+, and 4B.

My only concern now is using the keyboard and mouse for the initial set-up (it will be used headlessly after that) --- I'll probably use a powered USB hub for that.

Thanks.

--
I never met a people who were better at not getting to the  
point than the Brits.                         ---Rich Hall

Oops, forgot the link:

--
There's no money in poetry, but there's no poetry in 
money either.                       ---Robert Graves

Even further since the 1.5MB cartridges I used on an IBM 1130 in the mid 1970s - they were much less power hungry but took several minutes to spin up or spin down. The day I corrupted the system disk it took nearly forty minutes to shut the drives down, boot from a copy, restore the corrupted disk and put everything back the way it should be about three minutes before the operator returned.

--
Steve O'Hara-Smith                          |   Directable Mirror Arrays 
C:\>WIN                                     | A better way to focus the sun 
The computer obeys and wins.                |    licences available see 
You lose and Bill collects.                 |    http://www.sohara.org/

A quick look at the M.2 specs seems to have them between 2 and 7 watts. Quite a bit higher than the SATA standard at about 2-3 watts. But 7 watts would be something to look out for with a rPi being 1.4 amps on USB.

I think if I were in the market for another drive I would go for a NVMe in a USB adapter rather than a T5. I tend to rotate old parts and a NVMe drive is more flexible.

I can just about see the use of a T5 if it were something to put in a pocket and carry around, but for any thing more static I would just use a standard drive and an adapter.

So what advantage did you see in the T5?

Thanks!

--
they're OK, the last days of May

I think that's a standard current draw limit as defined by the USB standard. In practise its a minimum: i.e. anything capable of supplying power over USB 2 or 3 connections will provide at least 1.5 amps (it was

0.5A for USB 1).

IOW, be guided by the power supply capability of your wall rat, powered hub, or whatever.

For a totally off the wall example, the moving map navigation aid in my glider (a Medion S.3747 PNA running LK8000) is powered by a 12v DC to 5V DC converter brick, connected to a 12v SLA. The converter, which was made for folks who bling up their cars with LED festoons and bought on eBay, delivers up to 3A, so can easily run(and charge) the Medion. I've been using that for 7 years with no issues.

--
Martin    | martin at 
Gregorie  | gregorie dot org

Price foremost. Also, Apple did use user changeable nvme drives for a while but with a proprietary interface, so a standard nvme drive wouldn't be of special use to me. Although I think there are adapters. And lastly, I did not buy it (them) for my Pi originally so yes, portability was good too.

Precisely. How much current the USB port can deliver is a function of what is powering the Pi until the circuit board traces from PSU to USB catch fire and fuse...

--
The theory of Communism may be summed up in one sentence: Abolish all  
private property. 

Karl Marx

On Thu, 15 Jul 2021 12:51:09 -0000 (UTC), Martin Gregorie declaimed the following:

For a data cable, USB 2 is spec'd to only provide a max of 0.5A (five

0.1A "units"). USB 3 was spec'd for 0.9A (six 0.15A "units"). USB 3.2 is spec'd for 1.5A.

USB-C cables are spec'd for 1.5A or 3A loads.

Power-only cables and charging-only ports are 1.5A (v1.1), and 5A (v1.2).

--
	Wulfraed                 Dennis Lee Bieber         AF6VN 
	wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/

(five

These limits are amazingly badly defined: I looked at several sites that claimed to describe the USB standards, none of them entirely clear and not all agreeing with each other. This is why I think its probably good enough to check that your power source has enough output to meet the requirements of what its meant to power and assume that the conductors in the cable used to connect one to t'other will be up to the job, i.e. meet the current carrying capacity implied by the lowest rated USB connector on the cable [1].

[1] probably a dodgy assumption for el cheapo USB cables, so avoid those.

--
Martin    | martin at 
Gregorie  | gregorie dot org

The washing-machine drives I worked with in the 1970s (25MB) had interlocks built into the motor circuits so if you punched the ON button on more than one at a time it would sequence them so that one drive was up to speed before the next started.

Amen, brother. 10,000 time the capacity, 1/100 the cost - factor inflation into it and you have a drop in cost per byte of seven orders of magnitude. Mind-boggling.

--
/~\  Charlie Gibbs                  |  They don't understand Microsoft 
\ /        |  has stolen their car and parked 
 X   I'm really at ac.dekanfrus     |  a taxi in their driveway. 
/ \  if you read it the right way.  |    -- Mayayana

I thought there was actually a polyfuse in there somewhere?

...And the PCB traces on the Pi itself... used to connect one to t'other will be up to the job, i.e. meet

It isn't the current carrying capacity so much as the drop in volts

I wired up my kitchen with some 12V LV lamps - each lamp takes around 4 amps, so I used 16 A rated 'lighting cable' - BIG mistake.

The lights were perceptibly dim...a couple of volts drop isn't much at

240 volts but it sure is at 12 volts!

--
There is nothing a fleet of dispatchable nuclear power plants cannot do  
that cannot be done worse and more expensively and with higher carbon  
emissions and more adverse environmental impact by adding intermittent  
renewable energy.

There may well be. I have never looked

--
Truth welcomes investigation because truth knows investigation will lead  
to converts. It is deception that uses all the other techniques.

If it's mostly read access, and 256 GB suffices, you might consider a 256 GB USB stick, as there's not that expensive.

I see 1 TB at a similar price, but I would buy a brand I trust!

--
Cheers, 
David 
Web: http://www.satsignal.eu

Good point - yet another reason for avoiding cheap-looking USB cables, the really thin, stiff ones.

As I previously said: avoid el cheapo USB cables and buy the thicker, more flexable ones - you won't regret it.

--
Martin    | martin at 
Gregorie  | gregorie dot org

Beware!

A USB HDD needs power which it draws from the USB socket on the Pi. For an SSD you might be OK but if you use a spinning HDD there is insufficient power, so the +5V voltage may drop.

The solution to this is to use a powered USB hub. I did this for my Pi3 and everything worked perfectly. But for the Pi4, the Pi would not boot if the power to the USB hub and to the Pi were applied at the same time - for example after a power cut. Ass soon as I unplugged the hub from the PI, it booted immediately, as if it had been hanging indefinitely. It's to do with the hub supplying power upstream to the Pi as well as downstream to the HDD, which for some reason the Pi3 is happy with but the Pi4 is not. I tried a different make of hub and also a special USB cable between Pi and hub in which I had cut the +5V wire, but to not avail.

I had to adopt a different solution: a SATA HDD and a USB-SATA hub. That allows power to USB-SATA hub and Pi to be applied at the same time, and the Pi boots OK.

In my case, I specifically want a spinning disc because the Pi is used as a PVR, recording TV programmes, so there is a lot of writing and rewriting of data (around 0.5-1.5 GB/hour of recording), and I didn't want to knacker an SSD with frequent writes - the same reason than defragmenters are not recommended for SSDs.

...not to mention the size reduction. The OP refers to a 100-MB drive the size of a washing machine. Several of the 3D-printer motherboards I've bought lately have had 128-MB MicroSD cards bundled with them. That's the capacity of the washer-sized drive and then some, shrunk down to something about the same size as a fingernail...and I think they're making them in at least half-TB sizes nowadays.

(My direct experience with old hard drives is a bit more modest. My first was a Conner CP340, a 3.5" half-height SCSI 40MB drive that I used with an Apple IIe. Someone once gave me an IBM PC/XT with a Seagate ST225 in it (and it still worked!); that'd probably be the oldest and (physically) largest drive I've dealt with, with the only other 5.25" drives being the Quantum Bigfoot drives that were briefly a thing in the mid-'90s.)

_/_ / v \ Scott Alfter (remove the obvious to send mail) (IIGS(

Top-posting! \_^_/ >What's the most annoying thing on Usenet?

largest