Sd card speed with usb storage
#1
Hi guys!

I just purchased my first rpi and I am going to install openelec on it to use it as living room media center.

I also bought usb 3.0 8gb stick and a class 10 8gb sd sandisk card.

If I use usb stick as a storage drive, does the speed of the card matter? I have a 2gb class 4 micro sd with an adapter laying somewhere around the house and if there is no speed difference, I'd rather use that one and return the new one.

Thanks in advance
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#2
(2014-01-17, 20:36)ruicosta Wrote: does the speed of the card matter?
No, not really maybe 1 or 2 seconds in boot time.
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#3
Thanks, I'll return the new one then.

If I was using only a card (without usb drive), would it matter then?
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#4
You have a choice, either install on SD card solely, or install boot partition on SD and file system on USB.
Wherever you file system is installed is where the speed is important.

So yes, SD install -> SD speed important.
USB install -> SD speed does not matter (but USB speed matters).
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#5
If you're going to go the USB install route, check that the USB stick is actually faster than the SD card! Smile

I've been using a 16GB Samsung class 10 SDHC card and hdparm shows a block read speed of 18MB/s which is close to the theoretical limit of the SD card slot in the Pi. (20MB/s ?)

With an older 8GB Sandisk cruzer Titanium USB stick (SDCZ7-8192) I see about 25MB/s - a worthwhile improvement. Although its a number of years old now it was one of the fastest USB sticks you could buy at the time (and quite expensive) and one of the first Vista ready boost certified sticks.

I then tried a fairly new Sandisk cruzer 32GB USB stick (plastic case, SDCZ36-032G) and I only get 13MB/s in the same test - so for read speed its slower than the SD card!

As it was the 32GB stick I wanted to use I decided to stay with the SD card. The performance improvement with the fast USB stick install was quite noticeable but not enough for me to go out and buy a high performance 32GB USB stick.

I think I see more subjective improvement in performance from changing from ext4 to f2fs in a recent raspbmc update than going from SD to the fast USB stick. (Although all improvements are cumulative!)
Kodi 18.3 - Mid 2007 Mac Mini, 4GB, 2TB HD, Windows 7 SP1
Kodi 18.3 - Vero4k, Raspberry Pi 2. OSMC.
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