Sd Card Questions


Very Active Member
Sep 28, 2008
Didn't know whether to necropost an old topic or start a new one, obviously plumped for the latter. I've checked the blog SD guide and my questions aren't answered so I was wondering whether you'd indulge me...

I've got two different class 6 cards (here and here). My plan is to have the OS running off one of them, and the other to just have files.

I've checked the reviews and it seems that the Transcend has better overall sustained throughput speed, but the Samsung has better I/O speed. This means the Samsung will be better for the OS, is that right? I'm under the impression that a better I/O performance will pay dividends for the OS because of the small random read/write operations, correct me if I'm wrong.

Also, what is the best filesystem for the OS card? I'm happy to leave my second card as FAT. But I want high performance for my OS card and don't care about Windows etc. compatibility. Even if people think there will be little real-world benefit from going EXT2 or whatever as opposed to FAT, I'd still prefer to go that route because I'm happy to percieve a performance increase from the placebo effect. I'd prefer an explaination of the pros and cons of the different filesystems rather than a 'x is the best' so I can make a more informed decision.

I'm thinking EXT2. EXT3 would be a bad choice because of the journalling, is that right? And what about EXT4, still the same issue so best to go for EXT2 still? I'd prefer not to go for some obscure filesystem just to be different, I'd rather go mainstream Linux so I'm looking at the EXT formats specifically. But if someone has some other suggestion I'd be happy to hear it.

Also, is there a good program for testing the speeds? I use Windows mainly at the minute, but I have access to Linux if necessary, so a program on either platform would be ok. Not that I don't trust the reviews, but I'd like to see for myself.

Just keep the OS in the internal memory and use both of your cards for you applications and your datas.

And since it seems that you're using windows on your main machine, stick to FAT, it'll be easier to transfer your datas.
If you have file that weight more than 4Go, you'll have to watch for EXT or NTFS (don't know if NTFS is supported on pandora, but it should with NTFS3G).
These are the most common setups we have had during devel:

sd1 with fat for boot
sd2 with ext2 to run OS (also has to hold any data)

sd1 with fat for boot, and second partition EXT2 to run OS
sd2 any filesystem for data (im using fat32 for compat)

Also the NAND will be the default for the OS for production, so SD1 and SD2 would be free for data.
ive got the transcend ones and they are showing 13mb read sustained over the 16gb


complete test

Warning: Only 15379 of 15380 MByte tested.
Test finished without errors.
You can now delete the test files *.h2w or verify them again.
Writing speed: 11.0 MByte/s
Reading speed: 18.3 MByte/s
H2testw v1.4
thats better
Lexar 512MB SD
Test finished without errors.
 You can now delete the test files *.h2w or verify them again.
 Writing speed: 3.18 MByte/s
 Reading speed: 5.55 MByte/s
 H2testw v1.4

Haha... pretty bad. Glad I have an SDHC hanging around. :lol: