Hi,
For a lightweight server based on a Pi 3 or 4, the recommendation was to use an externally powered USB hard drive (rather than powering it from the Pi's USB port) for better reliability.
Now that you can get external USB SSD units (which draw less power than HDDs) is it OK to use one for this? I had in mind something like a Samsung T5 or T7 500 GB USB SSD.
Thanks.
I don't know about the pi3, but my pi4 works fine as a NAS with a Samsung SSD (500 GB 860 maybe?) and USB3 to SATA cable.
I guess that is similar to the T5, T7.
I also have a 2.5" hdd, but that does require an additional USB power supply.
Do they actually use less? The T5 spec says 4 Watts, I can see Tom's hardware measured a spinning 500GB Samsung USB at 2.7 Watts ... OK one of those is a spec, the other is as measured ...
That's when it is spinning - the startup current is (can be) more of a problem. Having said that, I have a 4TB drive connected to a Pi4 without external power but a 5TB drive requires an extra 5V supply. Also (second-hand) 250GB M2 drive in M2-USB3 converter case.
-- Chris Elvidge England
Typically the flash will use a lot less when idling. Both will take more power when being accessed, but the HDD still needs to spin while the SSD can sleep. The HDD could spin down but then the access time when it needs to power up again is measured in seconds.
Theo
Yes. Works perfectly for me, no trouble for years with a T5.
Where did you find the specs for the USB SSDs? I googled various combinations of keywords, then focused on the Samsung website, without being able to find any numbers for current or power.
--
A person who won't read has no advantage over one who can't read.
---Mark Twain
I'd expect the difference between running and start-up currents to be a lot less for an SSD than a drive with a motor --- is that correct?
-- Consistently separating words by spaces became a general custom about the tenth century A. D., and lasted until about 1957, when FORTRAN abandoned the practice. ---Sun FORTRAN Reference Manual
That makes sense, thanks.
-- Consistently separating words by spaces became a general custom about the tenth century A. D., and lasted until about 1957, when FORTRAN abandoned the practice. ---Sun FORTRAN Reference Manual
Thanks. (I didn't know USB SSDs had been around for years.)
5V 0.8A
The T5 was introduced in Aug 2017 but the 500GB version was ?199,-! I think I bought my first one when it had dropped to ?100. Now the 1TB version is down to that..
Definitely.
Yebbut.... no details whatsoever. Is that max on startup, max in use, typical while reading, writing? Etc. It seems quite high; mine doesn't get warm which I would expect at constant 4 W.
bearing in mind they might have altered the internals since 2017, but it gives a guide. I note the spikes up to 3.5W which would accord with a PSU rating of 4W.
Theo
Thanks!
I've used an SSD with Pi 3Bs, 3B+s and 4Bs. As long as you use a good power supply, the Pi can drive these with no issues.
---druck
My M.2 NVMe in a cast aluminium soap-on-a-rope gets pretty hot ...
Yes! I recently swapped such a drive in an old Macbook (where this was still possible) and put the old one in an external enclosure; it gets quite hot just from being plugged in. But the T5s don't.
As an extreme case, I remember a washing machine sized 100MB disk drive on a VAX minicomputer I managed in the early 1980s, which took 240V three phase power and drew some 100 amps for the first second until the magnetic field and the back emf built up in the motor windings. We had to fit a slow-blow fuse to the circuit to prevent it failing on switch-on.
We have come a long way since to reach a couple of amps on 5V for a disk of
10,000 x the capacity and a minute fraction of the cost.-- Paul at the paulhardy.net domain
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