Re: Very slow transfers to/from micro SD card on a RPi B+

[Jasper Wallace <jasper%pointless.net@localhost>]

On Thu, 9 Jul 2015, Jean-Baka Domelevo Entfellner wrote:

> Hi there,
> 

> It's on average between 0.20 and 0.25 MB/s, don't you think it's
> unreasonably slow? Do you have any piece of advice for me?

SD cards suck with the many small writes workload typical of *nix 
filesystems.

The OLPC project did some work on trying to find out why that was and some 
work on what needs to be done to fix it, link dump follows:

https://wiki.linaro.org/WorkingGroups/KernelArchived/Projects/FlashCardSurvey
http://wiki.laptop.org/go/SD_and_USB_FLASH_Drive_Performance
http://wiki.laptop.org/go/How_to_Damage_a_FLASH_Storage_Device
https://github.com/bradfa/flashbench
http://wiki.laptop.org/go/SDCard_Testing
https://superuser.com/questions/801023/how-to-inteprete-these-flashbench-results-for-a-sandisk-sdcz48-064g

In an ideal world OS installs for raspberry pis and things would include 
running from a ram disk, benchmarking the SD card to determine erase block 
size etc, and then formatting the SD card appropriately.

-- 
[http://pointless.net/]                                   [0x2ECA0975]