Disk Usage: 100%

[Marek Scholtz]

Hi, I bought SD card with UHS-I, SD adapter which supports UHS-I and connected it to USB 3.0. Windows is reading with speed 90 MB/s and writing with speed 45 MB/s. I made two partitions FAT32 for installing android-x86-4.4-r2.img and EXT3 to save Android's data. I successfully installed and boot Android from SD adapter but I have problem with disk speed.

CPU is working without problems:
https://imageshack.com/i/ipBT22pBj


RAM without problems, too:
https://imageshack.com/i/f0tibNFwj


but Disk Usage is still at 100%:
https://imageshack.com/i/exYqrGp2j


Apps are loading too slow, sometimes Android needs soft reset and SD adapter is overheating but "it's doing nothing". Thanks!

[Thomas Hoberg]

I've tried similar things, but used a "fast" USB3 stick instead and noticed
similar effects, perhaps not quite as bad as you describe, but certainly
disappointing.

Things improve once I use an SSD with a USB3 interface and even good old
80GB 7200rpm hard disks aren't all that bad with Android on a USB 3 port.
And a 'truly smart' USB3 stick using a full blown SSD controller internally
might just do it, but require metal colling fins.

45MB/s is what vendors of these SDcards see when they write data at perhaps
2MB (erase) block size per I/O command *and* without having to erase first.

When Android needs to do 512byte block random access writes and there is no
command queue (or that was filled with 512 byte block writes) there is a
chance I/O can actually take seconds to complete and thus Android is timing
out.

SDcards are not a replacement for smart eMMC or proper SSDs with smart
controllers with DRAM to hold indirection tables etc.
They are essentially modern tape devices, meant for media storage not to
run a disk operating system such as Linux.

Android tries very hard not to be a disk operating system, but as Android
apps grow to mega and gigabyte sizes and run on octa core CPUs with
gigabytes of DRAM, occasionally some good old random access does creep in.

Actually some modern Compact Flash cards are starting to have full SATA
command set support and SSD speeds, but if you consider the size of these
SDcards even a single Watt of compute intelligence means there is no
thermal budget left to Flash.

[Marek Scholtz]

So if I understand you, now it is not possible to speed-up OS and
installing to SD card wasn't good idea?

[Thomas Hoberg]

I feel with you, because I've fallen into the same trap, but there are
physical and technical limits difficult to overcome in that form factor and
energy envelope.

If you have USB 3 available you still have a lot of options, but it will
require some very careful research to find out what combination of host
port (and driver), bridge chip (and driver) and USB storag device will give
you the best performance for your financial, energy, space budget and
reqirements.

Post by Marek Scholtz
So if I understand you, now it is not possible to speed-up OS and
installing to SD card wasn't good idea?

[The Black Death]

That brings me back to the Old School days, When I wrote an Assembly
Program to turn my 350 bps Modem into a 450 bps modem, It'd work at 450 but
data would become scrambled, And yes it was confusing,we figured out The
bus couldn't handle the speed of the Input, So It basically would choke,
The Trick was to Buffer it... and Give it as the system could receive it,
Not sure if it's the same idea of what your saying but sounds close.....

TBD

Post by Thomas Hoberg
I've tried similar things, but used a "fast" USB3 stick instead and
noticed similar effects, perhaps not quite as bad as you describe, but
certainly disappointing.
Things improve once I use an SSD with a USB3 interface and even good old
80GB 7200rpm hard disks aren't all that bad with Android on a USB 3 port.
And a 'truly smart' USB3 stick using a full blown SSD controller
internally might just do it, but require metal colling fins.
45MB/s is what vendors of these SDcards see when they write data at
perhaps 2MB (erase) block size per I/O command *and* without having to
erase first.
When Android needs to do 512byte block random access writes and there is
no command queue (or that was filled with 512 byte block writes) there is a
chance I/O can actually take seconds to complete and thus Android is timing
out.
SDcards are not a replacement for smart eMMC or proper SSDs with smart
controllers with DRAM to hold indirection tables etc.
They are essentially modern tape devices, meant for media storage not to
run a disk operating system such as Linux.
Android tries very hard not to be a disk operating system, but as Android
apps grow to mega and gigabyte sizes and run on octa core CPUs with
gigabytes of DRAM, occasionally some good old random access does creep in.
Actually some modern Compact Flash cards are starting to have full SATA
command set support and SSD speeds, but if you consider the size of these
SDcards even a single Watt of compute intelligence means there is no
thermal budget left to Flash.

[Marek Scholtz]

It sounds close but I think it is not the same problem. My SD adapter has
problem with saving data in real time. When I remove parameter DATA= from
grub.cfg, it is running without problems and really fast. On the other
hand, when I try to change paramater DATA= to another drive for example
sdc1 and Android is running from sdb1, Android is still too slow.