Running 2.2 or 3.0 off a MicroSD

[heinkel]

Is write speed of the SD card really most important? I've tested 3 cards:

Kingston 4GB Class 4: (Both OS's pretty much unusable - way too much lag)
Read 18MB/s, Write 4.45 MB/s

Patriot 4GB Class 4: (Both OS's pretty much unusable - way too much lag)
Pretty similar..17MB/s read, Write around 4.6MB/s

Sandisk 4GB Class 4: (Both OS's run nearly full speed)
Read: 10 MB/S, Write 6.2MB/S

I also have an A-data Class 6 which works better than the Kingston and Patriot, but not as good as the Sandisk. Just a tiny little bit of lag noticeable.

Logic would tell me that if I'm running an OS off of a SD card, read speed would be most important..but that doesn't seem to be the case, is this correct? Any other good/cheap SD card recommendations?

 

[ClintRo]

Scan disk IMO is the best quality sc cards.

 

[heinkel]

Just did the SanDisk (which runs 2.2 and 3.0 GREAT) vs the A-data Class 6 card (which runs them both decent, just not as good).

SanDisk:
R: 10.2 MB/s W - ~6MB/s

A-Data
R: 19MB/s
W: 10.1 MB/s

Why does the SanDisk run so much better, if the specs are slower??

 

[robteaboy]

I'm a WP7 user who got a NC to experiment with android and have fun with it. Actually from that angle, this makes sense to me. The class of the card along with read/write speeds has no impact on the speed of using the card as an OS. Here's and engadget link on WP7's sd card mess...

Windows Phone 7's microSD mess: the full story (and how Nokia can help you out of it) -- Engadget

here's the paragraph that applies to the uSD card for an OS drive...

"What we've learned from our tipsters and from documents culled from Microsoft, Samsung, and others is that the big issue is random access performance -- a figure that isn't taken into account in a card's class rating. Ironically, Microsoft discovered in its testing that cards with higher class ratings actually performed worse on Windows Phone 7 because the tweaks card manufacturers make to achieve high sequential throughput can actually hurt random access times. There's some rocket science involved here, but basically, it's a tradeoff and a bit of a gamble -- if a manufacturer tunes a card for a high class rating, it takes more time to access the first byte at a new location on the card because it's optimizing access for that area of memory, but once it does that, it can blast sequential bytes at very high speed. If you've got a lot of small reads or writes you need to make to different files at different locations in the card's memory, though, you really start to suffer. Cards with lower class ratings tend to spend less time optimizing sequential access prior to the first read / write operation, so it can move around the card (that is, access it randomly) much faster."

The same logic should apply to the NC.