2014-02-28, 05:25
I read a website that claims installing RPI XBMC distro to USB 3 vs the SD card is faster. Has anyone found this to be true?
2014-02-28, 11:04
See FAQ or search this forum. There is a lot of information out there about this manner.
2014-02-28, 11:51
I can't complain about my SD card performance - my class10 is behaving nicely. Also, having a 512 MB PI running OpenElec, the entire OS is loaded into RAM, so once booted it's supposed to be even faster than RaspBMC and Raspbian that move part of the OS to USB. The main bottleneck is and will always be the CPU. Outsourcing the userdata+library to USB is supposed to speed things up, but as I wrote earlier, for me my class10 SD is just fine.
2014-02-28, 17:26
I noticed a small speed improvement with a USB install on Raspbmc but it wasn't enough to warrant the extra complexity and losing a USB port IMHO.
It depends very much on the relative speed of your SD card and USB stick. Some SD cards are very slow while some are quite fast so if you have an SD card that achieves nearly the full potential throughput of the SD card interface on the Pi (20MB/sec) then a USB stick won't be more than about 25% faster as the USB interface on the Pi seems to top out at around 25MB/sec regardless of what USB stick/drive you use. (And some cheaper USB sticks are actually pretty slow - if you use a slow USB stick you'll be worse off) Remember also that the Raspberry Pi is only USB 2.0 so most of the speed gain of a USB 3.0 stick won't be realised.
I'm quite happy with the performance of an SD card install - my class 10 Samsung 16GB SD card gives a full 20MB/sec read performance and about 9MB/sec write performance, on a fairly fast USB 2.0 stick I saw 24MB/sec read and 12MB/sec write and the subjective performance gain was quite modest. (There are a few SD cards that can approach 18-20MB/sec for write performance as well)
I saw more of a subjective improvement changing filesystem from ext4 to f2fs in the recent raspbmc update - it seems to handle writes much better so there are less stalls waiting for things to be written back to disk. Also the Gotham nightly's are very much more snappy than Frodo on the Raspberry Pi, so expect a nice speed boost when Gotham goes gold as well.
It depends very much on the relative speed of your SD card and USB stick. Some SD cards are very slow while some are quite fast so if you have an SD card that achieves nearly the full potential throughput of the SD card interface on the Pi (20MB/sec) then a USB stick won't be more than about 25% faster as the USB interface on the Pi seems to top out at around 25MB/sec regardless of what USB stick/drive you use. (And some cheaper USB sticks are actually pretty slow - if you use a slow USB stick you'll be worse off) Remember also that the Raspberry Pi is only USB 2.0 so most of the speed gain of a USB 3.0 stick won't be realised.
I'm quite happy with the performance of an SD card install - my class 10 Samsung 16GB SD card gives a full 20MB/sec read performance and about 9MB/sec write performance, on a fairly fast USB 2.0 stick I saw 24MB/sec read and 12MB/sec write and the subjective performance gain was quite modest. (There are a few SD cards that can approach 18-20MB/sec for write performance as well)
I saw more of a subjective improvement changing filesystem from ext4 to f2fs in the recent raspbmc update - it seems to handle writes much better so there are less stalls waiting for things to be written back to disk. Also the Gotham nightly's are very much more snappy than Frodo on the Raspberry Pi, so expect a nice speed boost when Gotham goes gold as well.
2014-03-01, 16:41
The main benefit of running off USB is stability with higher overlocks.
2014-03-01, 18:52
oh, i was under the impression, that recent firmware fixed suspected cause of sd card corruption on failed OC crashing?
2014-03-01, 19:02
(2014-03-01, 18:52)Dam0 Wrote: oh, i was under the impression, that recent firmware fixed suspected cause of sd card corruption on failed OC crashing?
Yes, I believe there is now no stability difference between sdcard and usb installs with overclock.
I believe the fastest USB install will beat the fastest sdcard install, but it varies a lot with the actual device.
The class 4 Samsung sdcards (now class 6) sold on the Pi Store had much better performance than most class 10 cards.
Where performance matters is in the random 4K read benchmarks. Class 10 only guarantees the minimum continuous write speed, which is of little importance when running xbmc.
