Questions abour RPi 4B

I've got a Pi 3B+ and I'm thinking of upgrading to a 4B, partly to free up
the Pi 3 to do other tasks.
I've got a couple of questions?
- Can a "system disk" SD card (ie the same disk image) for 3B+ be used for a
4B? Is it a case of "yes, but you won't be making full use of the 4's 64-bit
architecture and larger RAM"? I'm being lazy and avoiding installing and
configuring everything all over again unless I have to ;-)
- I've read reports of the Pi 4 running quite hot and needing a cooling fan,
as opposed to just passive heatsinks, when used in a case.
I'd be using it for recording TV (using external USB DVB decoders) to a
spinning disk (*) (not to the SD card), using TVHeadend, for SMB-sharing
folders which are accessed by Windows PCs, and maybe also for running simple
software such as a browser or an email client. On my 3B, the CPU usage is
barely measurable for recording from three different sources simultaneously,
while serving one of the video files to a Windows client, but it shoots up
to nearly 100% as soon as I run Firefox or Chromium, even when a static page
has been loaded. Is it a known problem with the Pi 3 (maybe fixed on the Pi
4) that browsers tend to hog the CPU?
(*
) Driven by a powered hub, not by the Pi's PSU.
Reply to
NY
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As long as you've got the latest updates, you can just move the SD Card over.
I'd still stick with the Raspbian 32 bit userland until 64 bit OS's support everything such as GPU accelaration and GPIO libraries.
You can run the normal 32 bit userland with the 64 bit kernel, by adding one line in config.txt You can then install raspbian-nspawn to run 64 bit applications alongside 32 bit ones.
You don't need a fan, the large passive heatsink cases work well. I've got one Pi 4B with that, and one with a fan case. The latter runs cooler, but the former is well within spec idling at 45C and going up to 65C under load.
That shouldn't change.
You'll see a massive difference using web browsers thanks to the extra memory and processor speed. Browsers that use separate tasks for each tab can make use of all that extra memory even though they are 32 bit.
---druck
Reply to
druck
Everything druck said but cause they are cheap, I would get a fan case. I've got several but like the one from Canakit the best when I don't need access to the GPIO pins. I haven't tried the big metal cases but they look interesting. You'll really like the performance increase over the 3 when using a browser!
knute...
Reply to
Knute Johnson
Yes, as long as the version of Raspberry Pi OS (aka Raspbian) supports the Raspberry Pi 4. In other words it must be pretty recent.
--
Brian Gregory (in England).
Reply to
Brian Gregory
My Pi 3B+ has Raspbian Stretch which I believe is one "level" below the current Raspbian Buster. I wish computer companies would go back to using version *numbers*, instead of Ubuntu Bionic Beaver, Android Jelly Bean or Raspbian Stretch. At least Ubuntu uses consecutive letters of the alphabet so Bionic Beaver is one version before Cool Cat and two before Dirty Dog (or whatever!).
It's not the end of the world if I have to reinstall from scratch. I had to do it a while ago when my Pi suddenly stopped booting after I'd done a clean restart (not even a shutdown, and certainly not an unclean loss of mains). After trying all the remedies that Google offered, I cut my losses and reinstalled it, making copious notes of what I'd installed and any configuration tweaks, in case I needed to do it again. I also started making a disk image of the card every few months so I could go straight back to a reasonably recent state without needing to reinstall. That card image will be my initial system disk for my new Pi 4; all I need to do is to remember to change the /etc/hostname and /etc/hosts entry to give the new Pi a different name.
Grrr. Just realised I'll need to buy either a mini-HDMI to full-size-HDMI converter or else a longer mini-to-full HDMI cable, so the Pi can reach the telly which I'll be using as a monitor - when I'm not accessing the Pi's desktop remotely using VNC.
Reply to
NY
Assuming you're making backups with dd or tar, zip etc, you might want to look into using rsync instead:
- its faster because it does the minimum work needed to bring your last backup up to date
- its more flexable because its copying files and directories into a backup filing system which gives you direct access, should you need it, to individual files on the backup volume and recovery to a differently sized disk partition is a lot easier than doing so from a backup made with dd.
--
Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie
[Snip]
You shouldn't need to, I upgraded my whole dozen strong collection including every generation of Raspberry Pi, from Stretch to Buster, and didn't loose any of them.
When promoting a card to a later machine, I've occasionally found a newer kernel and startX.elf isn't present, using rpi-update on the older machine before moving the card fixes that.
I'd go for a micro HDMI cable, as I don't like the idea of a full size cable and bulky converter hanging off a small connector. Also if you ever want to drive dual displays, there wont be room for two converters.
---druck
Reply to
druck
I've got my dozen Pi's set up to backup nightly on to images on a NAS drive. I first make an image of each Pi's SD card using dd, then as part of the backup cron job, create a loop device for the image and mount it, then use rsync to backup whats changed each day. I've then got a weekly and monthly cron which bzips the images on to another backup disc.
The advantage of doing this, is if an SD card fails, you have an "oven ready" uncompressed image ready to dd straight on to a new card. It also means you can back up on to non-native network filing system such and preserve all the file attributes.
I was using a USB3 drive attached to my router as a NAS, which ironically was actually ext4 formatted, but the router would only share via SMB, which meant using images was necessary. I've retired that and am now using same drive attached to a Raspberry Pi 4. As that has USB 3 and gigabit Ethernet, its actually twice as fast as the router as a NAS. Another big advantage is it can share the drive as both SMD and NFS. Which means I could backup straight to the drive over NFS without using images, still preserve all the attributes, and it would take up quite a bit less space. In case of SD card failure, I would just have to partition the new card, and copy the files on, rather than using dd.
---druck
Reply to
druck
Lose - duh!
---druck
Reply to
druck
The adapter that the foundation sells avoids that because it's a little cable, see e.g.
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Reply to
A. Dumas
On Mon, 7 Sep 2020 11:31:08 +0100, "NY" declaimed the following:
Raspbian/Raspberry OS is a customized release of Debian, and follows Debian practice.
Debian does use version numbers -- they just aren't common in public discussion.
v7 Wheezy v8 Jessie v9 Stretch v10 Buster
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{The names are characters from Toy Story}
--
	Wulfraed                 Dennis Lee Bieber         AF6VN 
	wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/
Reply to
Dennis Lee Bieber
I found the boot partition was too small for all the latest raspberry pi 4 stuff when I upgraded my Raspberry pi 2 to Buster. It runs Raspberry pi 2 compatible buster fine though, just doesn't have all the latest boot files for the raspberry pi 4, which doesn't really matter in my case since it's just a very low traffic web server that can stay on the Raspberry Pi 2 for now.
Actually I think it would boot on a Pi 4, it just doesn't have the latest power optimization stuff.
--
Brian Gregory (in England).
Reply to
Brian Gregory
Good point, I'd forgotten about that. All my old cards only had a 64MB boot partition, but when the Pi 3 came out I followed recommendation to change it to 256MB. Even if the normal contents of boot is quite small, it uses about twice the space during an update.
I repartitioned most of my cards at that point, but only finished off the process for the Pi Zeros, 1s and 2s more recently to make everything consistent. This involved repartitioning my backup images on the NAS too, but the process is the same.
Pi 4 does need its own version of just about every file in boot, so don't try it with an old 64MB partition.
---druck
Reply to
druck
I backup data files on the Pi (weather station files) most days using MS SyncToy on Windows, via a SAMBA share on the Pi.
I was wondering what equivalent software was available on Unix for doing incremental / differential backups, so your posting has come at a useful time.
I agree that a file-and-folder copy onto the backup device is a lot more convenient than a backup that saves everything into one humungous file that needs specialised software (as opposed to a simple COPY or the equivalent) to recover and restore it.
But we're talking about two different things. My copy of the SD card (made by removing the card, inserting it into a Windows computer and running Win32 Disk Imager) is to restore a fully-working, bootable system, as opposed to backing up specific user-created files that cannot be restored by reinstalling OS and packages.
Reply to
NY
Yes I much prefer a short flexible cable rather than a dual-ended plug-and-socket when it's necessary to change between mini- and full-size HDMI or micro-USB and USB C, because it provides strain relief.
But the correct cable (eg mini HDMI plug on one end and full HDMI plug on the other) is the best solution.
Usually mini sockets are as good as the full size version than preceded it. The only exception is the mini aerial connector on one of my USB DVB TV adaptor devices. Instead of having a full size Belling Lee coaxial aerial socket (which may require the casing of the adaptor to be flared out at one end) they chose to use a miniature socket that is only about 2 mm diameter, and to supply a Belling Lee to mini adaptor (solid, not a short length of cable). The adaptor and socket do not mate properly and the adaptor pulls out if the aerial cable is wiggled slightly. So I've wrapped lots of tape around it to secure it to the USB device. The best plug/socket for that sort of thing is BNC: securely latches together but only needs 1/4 turn to release it, rather than faffing with the multi-turn screw of an F connector. But no-one uses BNC any more :-(
Reply to
NY
That's the problem: the set of names only "works" if you are familiar with what's being alluded to. OK, Toy Story is pretty mainstream, but US films and TV aren't really my "thing". VLC uses characters from Terry Pratchett's Discworld novels - again, a bit esoteric, even if fairly widely known. Android's naming suffers because the confections etc are US brands which aren't always as well known in the UK.
Numbers are better, because it is blindingly obvious how they should be sorted in increasing order of release. Same as for house numbers versus house names, when you are trying to find a specific house in a street.
Reply to
NY
Yes they do - just not on the type of equipment you're using, which includes many TVs and non-portable FM broadcast receivers. Probably because a tacky push-on connector is cheaper than a BNC type.
Every airband transceiver I've see has a BNC aerial connector - both panel-mount and hand-held. So do most 2m ban hand-helds and a lot of all- band scanners.
--
Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie
Not always - apparently in Tokyo house numbers within a block are assigned in the order that the houses were built, which is why all Tokyo taxi-drivers use GPS systems. That gem surfaced during the first GPS Millennium in 1999.
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Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie
Not really - I use the rsync backup for both. After a crash, use gparted to recreate the partitions and rsync or ftp to refill them. Don't forget that, even if you put /home in its own partition there is still system- specific stuff in other partitions (modified config in /etc, code in /usr/ local and possibly /opt) I long ago set up /home/local, which contains everything in /usr/local and replaced the /usr/local directory with a symlink pointing at /home/local. I also keep copies of all the config files that I modified in /etc in /home/backup/etc so they can replace the standard issue config files. Most of these are in /etc/profile.d /etc/ssh and /etc/postfix
If you want versioned backups rather than a single 'latest' version, take a look at rsnapshot.
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Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie
Do you need one of these?
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--

Chris Elvidge, England
Reply to
Chris Elvidge

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