3 ms·

Taking eight hours to migrate the data is almost certainly a software issue. Assuming the phone is completely full, transferring 256GB over USB 2.0 (480Mbit/sec

by ggreer 1y ago

Taking eight hours to migrate the data is almost certainly a software issue. Assuming the phone is completely full, transferring 256GB over USB 2.0 (480Mbit/sec, or 60MB/sec) should take about an hour and 15 minutes.

BobbyTables2 1y ago
I suspect the flash storage can’t sustain 60MB/sec writes indefinitely…
- ggreer 1y ago
  The iPhone line has used NVMe drives for a decade. Even the iPhone X can do sustained writes of over 100MB/sec.
- Dylan16807 1y ago
  The amazonbasics 256GB microsd is faster than that. I really doubt the flash in an iPhone is worse. And the speed you should actually expect from USB 2.0 is more like 35MB/s so that's even easier for flash to handle.
frollogaston 1y ago
USB 2.0 doesn't realistically do 480mbit/s I thought
- delfinom 1y ago
  It absolutely can. Many years ago the limitation was PC mobos sucked and the likewise flash drives sucked. They marketed it but it was often just a peak. Nowadays I can fully saturate the 480 mbit.
  - userbinator 1y ago
    No, real-world throughput is closer to 40MB/s (320Mbps) due to protocol overhead, which is relatively high.
userbinator 1y ago
USB 2.0 mass storage bulkonly protocol maxes out around 40MB/s due to protocol overhead and hardware limitations, and in practice it's closer to ~35MB/s. https://superuser.com/questions/317217/whats-the-maximum-speed-possible-with-a-usb2-0-drive https://superuser.com/questions/317217/whats-the-maximum-spe... ...which still gives ~2h as the amount of time taken to transfer 256GB. My suspicion for the slowdown (to around 8MB/s?) is the flash controller is doing read retries and applying ECC to compensate for retention failures.
xp84 1y ago
It probably is a software issue (though I usually assume USB-2 is more likely to be about half its raw rated speed), and if the pokey USB-2 speeds aren't a bottleneck that's truly ghastly. But it was an interesting data point to me. It's utterly ridiculous how long Apple devices take to do migrations now.

by ggreer 1y ago

BobbyTables2 1y ago

I suspect the flash storage can’t sustain 60MB/sec writes indefinitely…

ggreer 1y ago
The iPhone line has used NVMe drives for a decade. Even the iPhone X can do sustained writes of over 100MB/sec.
Dylan16807 1y ago
The amazonbasics 256GB microsd is faster than that. I really doubt the flash in an iPhone is worse. And the speed you should actually expect from USB 2.0 is more like 35MB/s so that's even easier for flash to handle.

frollogaston 1y ago

USB 2.0 doesn't realistically do 480mbit/s I thought

delfinom 1y ago
It absolutely can. Many years ago the limitation was PC mobos sucked and the likewise flash drives sucked. They marketed it but it was often just a peak. Nowadays I can fully saturate the 480 mbit.
- userbinator 1y ago
  No, real-world throughput is closer to 40MB/s (320Mbps) due to protocol overhead, which is relatively high.

userbinator 1y ago

USB 2.0 mass storage bulkonly protocol maxes out around 40MB/s due to protocol overhead and hardware limitations, and in practice it's closer to ~35MB/s. https://superuser.com/questions/317217/whats-the-maximum-speed-possible-with-a-usb2-0-drive https://superuser.com/questions/317217/whats-the-maximum-spe... ...which still gives ~2h as the amount of time taken to transfer 256GB. My suspicion for the slowdown (to around 8MB/s?) is the flash controller is doing read retries and applying ECC to compensate for retention failures.

xp84 1y ago

It probably is a software issue (though I usually assume USB-2 is more likely to be about half its raw rated speed), and if the pokey USB-2 speeds aren't a bottleneck that's truly ghastly. But it was an interesting data point to me. It's utterly ridiculous how long Apple devices take to do migrations now.