best settings for usb2 and attached disks, and sdcards

[Bernd Walter]

On Wed, Mar 07, 2018 at 06:15:25AM +0000, John wrote:
> Hi,
> [cc'd to arm@ and fs@ where it's also relevant]
> 
> I have a number of rpi3 & rpi3 machines. Usually I want to attach a usb keydrive to them so that the sdcard isn't thrashed. They're all running -current. usr/src and usr/ports at least are mounted on the keydrive.
> 
> When initially updating eg the ports tree, svn will time out/crash because of the poor write performance of these devices in a rpi2/3 context. The fs on the usb keys is always ufs2. I have tried mounting these devices as -o async and also in fstab but this parameter seems not to 'take' in that mount doesn't report the async property set:

I'm currently very pleased with the SanDisk Extreme Plus micro SD
cards.
They are quite expensive, but behave way better with random writes.

Event better in random write performance are the SanDisk Extreme
USB sticks.
Also quite expensive though and quite big.

I can't tell, however, if they are better in case of power loss
related data corruption.

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.