Hi Erik, On Tue, Jun 18, 2019 at 02:26:57PM +0200, Erik Josefsson wrote: > As far as I understand, it is quite recent that SD cards are fast and large > enough to be able to carry and run an entire Debian instance.
Not really recent. I've run Debian sarge on a 128MiB CompactFlash card and I'm sure people have done more extreme things than that. > If this is the case, maybe there is only theory available regarding whether > you can make a computer "run faster" on a 64GB SD card than on a 32GB SD > card when cards are otherwise identical. So firstly, SD cards in the general case aren't that performant or reliable. You can spend more money to get faster and more durable ones. The unique selling point of SD cards is the form factor – they're small and have no moving parts. They're meant to go in devices like cameras, dashcams, cell phones, etc. Given two SD cards that differ only in capacity, I would not expect their performance to differ. The bigger one may last longer (survive more writes) due to you using less of its capacity. > I don't really know how swap works on a standard computer, even less how it > works when the whole computer runs from/on a SD card. It doesn't work any differently, except that swapping onto SD generally isn't great because they aren't that fast and they often have fairly low write endurance. SD cards aren't like SSDs, even though they are both made from a form of flash memory. Modern SSDs and flash drives have much better write endurance than modern SD cards. > Swap is supposed to be make your computer pretend that you have more RAM > than it actually has, but if the whole computer is running from/on RAM (or > is it?), then what does swap mean? I don't know why you have introduced the concept of a computer running from memory, as that is a completely different topic. A computer running from SD card isn't much different to a computer running from an HDD or an SSD. It's just a block device. Now, due to the low write endurance of your typical SD card, some people — especially those making small single-purpose devices — do configure things to load off of the SD card into memory and then run largely from memory. This prevents writes into the SD card, thus prolonging its life. But that tactic is not in any way required when using SD cards and can be done with any block device. > On Teres-I with redpill RC2 (now there is a RC3 that I have not yet > installed) an unfortunate website with pop up commercials (like dn.se) can > eat all performance there is and freeze the mouse for hours. I would guess > that could have been fixed on a normal computer with "more RAM", i.e., "more > swap"? But is the same true for e.g. Teres-I? Sorry I am unfamiliar with Teres and redpill. > Second question is if it is meaningful to buy a "super duper blazing fast" > SD card for the task to run a whole Debian system? If you wish to run a general purpose operating system off of an SD card then yes I would suggest that the fastest and more durable one you can afford would be a good idea. But also consider a regular SSD as some of the low capacity ones may compare favourably in price with a specialist SD card. > There is a very expensive 64GB SD card from SanDisk that is called Extreme > Pro that costs twice as much as same size Extreme Plus. Specs say it is > "super duper blazing fast" for video in "Ultra HD 4K", but would Pro also be > faster than Plus for the task of running Thunderbird and Firefox at the same > time? Running big apps like that will benefit more from having enough memory. After that is satisfied, fast storage will certainly help. You'll have to look at the exact specifications of Plus vs Pro. What are you trying to achieve? Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting
