Recommendation for a USB 3, SSD drive for a Raspberry Pi 4B?

Jul 02, 2019 82 Replies

Yes, but ...

In a typical domestic setup, you're relying on the clients detecting which WAP is best for them as they move around the house, and many clients are s*it at deciding when to let go of a weak signal.

In a higher-end setup with a controller telling the WAPs what to do, it can boot a client off a specific WAP if it can tell it would get a better signal from another WAP.

So you might prefer named SSIDs such as upstairs/downstairs/outdoors, then you can connect the device to what you know is best for where it is.

And my laptop is s*it at hanging onto a strong one.

yeah, already done that.. bye bye seamless roaming :(

Still the PI is now toggling between 65 and 72mbps and the laptop in the bedroom, now its stable, is similar.

So that covers two pretty well used rooms and possibly a third and 4th..

"When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him." Jonathan Swift.

On 2019 Jul 07 18:49:20, you wrote to druck:

TP> Is it Ok to put three WAPS on the same SSID/password but on different TP> channels?

you can put them all on the same SSID/password and channel... then you can walk about without your system having to jump around from one to the other... it just keeps on keeping on and uses the new stronger frequency as it gets closer...

i'm aware of a church with 20something WAPs in just such a configuration... works beautifully...

)\/(ark

And to this end they built themselves a stupendous super-computer which was so amazingly intelligent that even before its data banks had been connected up it had started from "I think therefore I am" and got as far as deducing the existence of rice pudding and income tax before anyone managed to turn it off. ... A hormone-injected radiated chem-blasted feces-doused meat-like burger.

On 2019 Jul 09 08:56:20, you wrote to me:

AB> and likely a separate controller to co-ordinate the selection of AB> channels and which clients it will allow to associate with which WAP.

they're all on the same freq/channel as i wrote originally... they use the WAP with the strongest signal... since they're all on the same freq/channel, you can move about freely without any lags or delays waiting on the machine to negotiate a connection... there is no controller or selection of channels... the settings are all forced to use the same channel, SSID and passwords...

)\/(ark

And to this end they built themselves a stupendous super-computer which was so amazingly intelligent that even before its data banks had been connected up it had started from "I think therefore I am" and got as far as deducing the existence of rice pudding and income tax before anyone managed to turn it off. ... Illiterate? Write today for free help.

On 2019 Jul 09 16:47:36, you wrote to me:

ml>> you can put them all on the same SSID/password and channel... then ml>> you can walk about without your system having to jump around from ml>> one to the other... it just keeps on keeping on and uses the new ml>> stronger frequency as it gets closer...

ml>> i'm aware of a church with 20something WAPs in just such a ml>> configuration... works beautifully...

DH> Well, no, it isn't as simple as that.

it is/was as simple as that... no lie, no bullshit... in my 50+ years, i've never made it a habit to tell lies or made up anecdotes... maybe they were wifi extenders, though... i dunno... i just know what was working and how it was set up by the tech that did it...

[trim]

DH> There are complete wifi systems consisting of multiple APs with the DH> same SSID, but they communicate with each other so as to switch the DH> clients betwen the APs. They cost much more than the simple APs.

AIR, these were OTS purchases from best buy or office max or some place like that... maybe even newegg or amazon... each was purchased at different times as the need to extend the range grew...

DH> I would like to have a whole house system on one SSID, but BT want DH> more money than I'm prepared to pay, so I put up with two cheap APs on DH> different channels and different SSIDs.

we don't even use our ISP's crappy firewall box or any of its capabilities... it is a simple media convertor feeding our own firewall ;)

)\/(ark

And to this end they built themselves a stupendous super-computer which was so amazingly intelligent that even before its data banks had been connected up it had started from "I think therefore I am" and got as far as deducing the existence of rice pudding and income tax before anyone managed to turn it off. ... Beware of all enterprises that require new clothes.

well no, it doesn't

well no, it didn't.

"Corbyn talks about equality, justice, opportunity, health care, peace, community, compassion, investment, security, housing...." "What kind of person is not interested in those things?" "Jeremy Corbyn?"

and likely a separate controller to co-ordinate the selection of channels and which clients it will allow to associate with which WAP.

Cell networks have far more sophisticated switching, and even they make what seems to be non-optimal signal strength decisions so as to reduce the amount of tower switching. I used to look at Open Signal map which showed me which tower I was connected to while travelling on the train. The towers we pretty regular spaced along that track, but instead of switching to the next soon after it became closer than the current one, it often used to hang on to the current one, until well past the next one.

Or have a number of access points in the places WiFi is used most, all set to minimum power, so it is easy for the client to pick the the strongest signal. In places equidistant, it will probably be worse than one high power access point, but its never going to be perfect.

---druck

My understanding of RF theory sugggests that messing with the power levels isnt really going to help much. It will just change the point at which one WAP becomes preferable to another.

What is important is to keep adjacent WAPS wide apart in channel spacing.

Multipath degrades signal quality but it does not change channel frequencies!

If I had all the money I've spent on drink... ..I'd spend it on drink. Sir Henry (at Rawlinson's End)

A long time back I was on a contract at Vodafone, capturing and storing Call Detail Records, so am aware that switching a phone to another mast is relatively expensive in network terms. As far as I know there is only one switching algorithm used by all the cells in a network, so it will probably not be optimised for a phone moving at constant velocity along a relatively slowly changing vector as it does on a train: most phones will show a more complex movement pattern especially when you take account of signal strength variation in a city, and under these conditions there may well be an advantage in only switching as a phone starts to go out of range of its current mast rather than switching as soon as it comes in range of the next mast.

Martin | martin at Gregorie | gregorie dot org

ne.

Your analysis implies your belief, that switching comes at no cost whatsoever. As long as the current connection is well "good enough" you may as well hang on and save all that overhead.

/ \ Mail | -- No unannounced, large, binary attachments, please! --

As I said my laptop was worse. It was switching every 2-3 seconds.

?I know that most men, including those at ease with problems of the greatest complexity, can seldom accept even the simplest and most obvious truth if it be such as would oblige them to admit the falsity of conclusions which they have delighted in explaining to colleagues, which they have proudly taught to others, and which they have woven, thread by thread, into the fabric of their lives.? ? Leo Tolstoy

Well, no, it isn't as simple as that. If you just put simple APs on the same channel with the same SSID, the clients will get awfully confused, and you'll get abysmal results. Even if you put them on different channels with the same SSID, you'll still get abysmal results. (Been there, done that myself.)

There are complete wifi systems consisting of multiple APs with the same SSID, but they communicate with each other so as to switch the clients betwen the APs. They cost much more than the simple APs.

I would like to have a whole house system on one SSID, but BT want more money than I'm prepared to pay, so I put up with two cheap APs on different channels and different SSIDs.

David

I'm well aware of the cost, but as the connection was for mobile data, holding on to the current connection until it had an almost zero data rate, then switching to the next one when it was already well past its optimal data rate, was rather annoying.

---druck

Exactly - the aim is to make the signals from the access points in other

rooms much weaker than the one in the current room, so it is used in preference.

---druck

But then when you go into the other rooms, you will use the one from the fisrt room when you shouldnt be..

As I said, it moves the boundary, that's all.

"What do you think about Gay Marriage?" "I don't." "Don't what?" "Think about Gay Marriage."

Beware that M.2 drives come in SATA and NVMe versions - you need the right adaptor to USB. Since JMicron released a converter chip, NVMe to USB adaptors are now becoming available.

Theo

e

Whoosh, whoosh and thrice whoosh.

You are not going to get perfect reception in every room with a house like that. There are probably two or three places in the house that you use your phone/tablet/laptop the most, and those should have a lower power access points. In those places the nearest access point will dominate and give a fairly decent rate, elsewhere your mileage will vary.

---druck

k.

so I

Whoosh! As usual you've completely missed the point.

The speed of an update is a very good metric for how good your filing system is for general use, as it is a particularly file intensive operation, doing lots of small read and writes. If apt is 3x to 5x quicker, many other common operations will also be faster.

---druck

Isn't that what I said? Buy an M.2 SATA or M.2 NVMe drive.

I'd buy a USB 3.1 case and NVMe drive if I was in the market. But I have more than enough portable USB drives using old 2.5in SATA disks recovered during laptop upgrades to handle portable data needs for now.

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