SD Cards and speed


Prometheus

Well-Known Member
Joined
Mar 8, 2008
Messages
9,475
I've used a myriad of speeds (Class 4 and 6, and some older cards where this, of course, isn't specified) - all fine.
 

Tickles

Member
Joined
Apr 9, 2010
Messages
476
Location
UK
Someone correct me if I'm wrong (I'm as much asking as telling really), but I believe the class only makes a noticeable difference if you write a lot to the card quickly, e.g. taking high res photos. For general use with the Pandora the class shouldn't really matter.
 

WizardStan

Mega GP Mania
Joined
May 24, 2008
Messages
16,733
Someone correct me if I'm wrong (I'm as much asking as telling really), but I believe the class only makes a noticeable difference if you write a lot to the card quickly, e.g. taking high res photos. For general use with the Pandora the class shouldn't really matter.
that's correct. Writing a lot of data, such as large movie files, may take a while, but when it comes to playback and writing smaller files, we're talking fractions of a second in difference.


There's a bunch of cases where faster is strictly better, but for most things you need to judge cost vs speed. Personally I've found Class 4 to be the right price point.
 

levi

Still fresh, damnit!
Joined
Oct 6, 2008
Messages
12,455
Location
Somewhere off the coast of the EU
You might want to upgrade that guide, what with SDXC working (although whether all capacities work I'm assuming we can't know yet - what with there not being a 2TB SD card in existence).


Re SD speed, it's worth having faster if you're transferring videos to your Pandora, or a lot of music, photos what have you. As others have said, running the average Pandora app will be quick enough even on a slowish card (by today's standards). You'd want a fast card if you were planning to enable swap on your Pandora though.
 

Tor

Member
Joined
Oct 3, 2008
Messages
709
My own purely ad-hoc rule-of-thumb is: Get a class 6 card if you can get a good deal on it, if it's too expensive get a class 4 card. Faster than class 6 should only matter if you plan to put it into your PC to write large amounts of data to it.
 
Last edited by a moderator:

levi

Still fresh, damnit!
Joined
Oct 6, 2008
Messages
12,455
Location
Somewhere off the coast of the EU
Has anyone done any benchmarking on the SD interface yet? I know the SD interface on my netbook goes faster than the USB2 port on the same machine can - I'd hope the same would be true for the pandora.
 

WizardStan

Mega GP Mania
Joined
May 24, 2008
Messages
16,733
Has anyone done any benchmarking on the SD interface yet? I know the SD interface on my netbook goes faster than the USB2 port on the same machine can - I'd hope the same would be true for the pandora.
No official or scientific benchmarking that I'm aware of, but MWeston did see 16MB/s read speeds when he was experimenting way back with the prototype. It has a maximum theoretical limit of 24MB/s, but like most computer things, that relies on a lot of perfect scenario stuff that you'll never see in real life.
 

tsh

Active Member
Joined
Dec 19, 2008
Messages
773
Location
Cambridge
Website
Visit site
I've got one of the class 6 16GB cards that play.com was selling recently, will try and remember to do a test on one...
 

Grench

Forum Addict!
Joined
Oct 3, 2008
Messages
6,485
There still isn't a benchmarking thread with a common basis/program - unless one snuck in on me which is possible.


So, for uses other than media playback (where the difference would be nil), there isn't much information yet.


If you're planning to boot an OS off of SD and use this as a computer and not just a PMP - the speed is important.


I have a pair of 32GB class 10 Patriot cards that I bought the last time my Pandora seemed 'weeks' away instead of 'months' (which was about 6 months ago). I have other uses for them until my Pandora arrives.


Still, it would be nice for us to have a thread where we can all use a common benchmarking program and post what stats we get from what cards.


Gruso's guide makes good sense for buying any flash memory - avoid Ebay. But it doesn't get into the heart of the matter - at what point is the SD card fast enough that it is no longer capable of being a bottle neck to the Pandora itself.


Class 2 and class 4 cards are fine for an MP3 collection that you're only planning to write once. Personally, I plan to run a database or two on the device and need some I/O responsiveness.
 

levi

Still fresh, damnit!
Joined
Oct 6, 2008
Messages
12,455
Location
Somewhere off the coast of the EU
It may be worth noting, the SD card class isn't a good indicator of real world use. It only tells you the minimum sustained write/read rate the card can handle - nothing about the average speed, and nothing about latency. I've had cards in the past that are only labelled as class 2 yet the specs say they're capable of more than 2MB/s (and they do seem to be in practice). Plus the classes for SDHC only go up to class 10 - 10MB/s. Plenty of inexpensive cards go much faster than that (or at least claim to). I say stick to a brand you trust, and only buy from sources you trust. For me that means two manufacturers, both of who have their own flash plants, and two retailers.
 

shadow.8

Member
Joined
Mar 5, 2008
Messages
211
Grench said:
...


Still, it would be nice for us to have a thread where we can all use a common benchmarking program and post what stats we get from what cards.


...
This sounds like a good article for the wiki. I ran a quick search and it seems it hasn't been made yet. Anyone know a good benchmarking program that works on Pandora?


http://pandorawiki.org/
 

tsh

Active Member
Joined
Dec 19, 2008
Messages
773
Location
Cambridge
Website
Visit site
dd if=/dev/zero of=/media/MEDIA/test.file bs=1M count=512


class4 PNY: 92.1s, 5.8MB/s


class6 Samsung: 69.3s, 7.7MB/s


Both cards 16GB, FAT32


Read to /dev/null


Class4: 15.3MB/s


Class6: 14.7MB/s


so not much difference.
 

Serafita

Still Fresh
Joined
Jul 4, 2010
Messages
21
Regarding SD brand names (I know you didn't ask, but I thought it's related in some way), I asked about that a few months ago on the other forum with recommendations. For a two page thread, I got the following:


Recommended brands:

  • Kingston (Prometheus, urjaman, Neko, Jdbye, mvickers03)
    Sandisk (Prometheus, Spirit, Neko, Chaser, God Ginrai, torpor)
    Verbatim (Prometheus)
    Bytestor (Prometheus, pootle)
    Play.com brand (Prometheus)
    Panasonic (pootle, God Ginrai)
    Integral (pootle)
    Toshiba (pootle)
    Micro Center (Mjlink)
    Extreme (Spirit)
    Topram (dgame)


Avoid:

  • fakes of any kind (Prometheus)
    A-DATA (Spirit, Chaser, God Ginrai)
    Peak (mvickers03)
 

levi

Still fresh, damnit!
Joined
Oct 6, 2008
Messages
12,455
Location
Somewhere off the coast of the EU
I only trust Sandisk and Samsung. Samsung have only recently started selling their own brand SD cards I believe, but they've been making flash chips for ages.


Is Extreme actually a make? Sandisk have a brand called Extreme - is it that?
 

Farewell

Still Fresh
Joined
Apr 20, 2010
Messages
28
I ordered 2 SD cards yesterday, a Kingston 16GB class 4 and a Transcend class 10... Is Transcend a reliable brand and will class 10 help with the likes of booting from SD?
 

Grench

Forum Addict!
Joined
Oct 3, 2008
Messages
6,485
I have several 4GB SD, 16GB SDHC and 32GB SDHC cards from Patriot. They have been solid for me.
 
Top