SD cards and performance

[wizardknight]

While working on my CM7 nook color I came across this thread talking about the random write speeds of SD cards.

http://forum.xda-developers.com/show....php?t=1005633

What I found was applying this idea to my TP2 made a good bit of difference.

I pulled out Kingston card
Kingston 4gb cl4 taiwan
Random Read 4KB (QD=32) : 1.866 MB/s [ 455.7 IOPS]
Random Write 4KB (QD=32) : 0.016 MB/s [ 4.0 IOPS]

and replaced it with a no name
no name 4gb cl2
Random Read 4KB (QD=32) : 0.900 MB/s [ 219.7 IOPS]
Random Write 4KB (QD=32) : 0.597 MB/s [ 145.9 IOPS]

I went down in class speed, but the over all responsiveness increased I would say. Now this is just what I had on hand. I am on a quest to find a Sandisk card with high random access times now.

This could make a big difference for a lot of people, but I never saw it referenced in the TP2 forums.

[arrrghhh]

bzo mentioned this on IRC - very good tip. The hardest part is finding one with a good balance. I see you found a card with better random writes, but worse random reads... Although that random write performance was AWFUL! Wow. That will definitely help!

The real problem is SD cards are designed to do sequential reads... not random. OSes use a lot of random... good tip indeed!

[wizardknight]

I got my hands on a sandisk (made in china) 4gb cl4 card today. Much better numbers.
Random Read 4KB (QD=32) : 1.966 MB/s [ 480.1 IOPS]
Random Write 4KB (QD=32) : 1.057 MB/s [ 258.0 IOPS]

[arrrghhh]

Originally Posted by wizardknight

I got my hands on a sandisk (made in china) 4gb cl4 card today. Much better numbers.
Random Read 4KB (QD=32) : 1.966 MB/s [ 480.1 IOPS]
Random Write 4KB (QD=32) : 1.057 MB/s [ 258.0 IOPS]

Yea, bzo said Sandisk have some of the best random r/w performance.

How's it feel in Android?

[orangekid]

moved to general TP on Android per the development forum rules

[mountainwampus]

I've tested a boatload of SD cards. I tried all sorts of fancy speed classes. Nothing works better than these old 1gb and 2gb Sandisk cards (class unknown). I never have a freeze result in a restart animation like I do with the 4gb+ classy cards.

[Kane3162]

I posted this a while ago on XDA, so I thought I would post it here since I still have my NIB TP2 sitting around and feel a sense of nostalgia every once in a while to check if a good/stable/uptodate NAND CDMA/GSM build is ready yet (read: still not Q_Q )

Dropbox - SD-Testing - Simplify your life

Something to note about ANY and ALL testing done, everything factors into testing performance... the USB hub's capacity/quality (each port on your PC is connected to a hub on your chipset, external/internal, its still a damn hub), the quality of the USB cable, and of course the quality/chipset of the SD/MicroSD card reader (internal or external, same thing, just internal has a directpath)... lets not forget the TP2's own chipset/reader quality...

I literally went through all 6 ports on my PC, found the best one after unplugging every port and doing the tests on each one (RDP connected to minimize CPU usage as well as need for my USB mouse/keyboard), and testing each USB cable I had as well (weird how 3 of the USB cables I had just blew ass and got about half the performance of the rest... bleh, shit cables are shit!), and of course the best media reader I had (out of 3)!

Another factor (lots of them eh?) of course pertains to REAL world performance and the file size's! what size's are the files most commonly used/accessed/needed things like that!

All this information is shown in my DB folder for my own personal MicroSD card testing!



And my LAST very important note here!!! IOPS is the MOST IMPORTANT thing to look for when your MAIN concern is its use for Android (SD version) as an OS, Android as an SD-EXT provider for program storage/access, AND of course SWAP usage! (kills cards quick, but the speed boost is definitely worth it! -to me at least because i do weekly full backups and of course dropbox backups whenever I change files monitored). If your only concern is transfering files to/from PC/Media, then you want the highest class and speed, if you want actual PERFORMANCE, well then Class 2/4/6 is going to have your best IOPS performance for any use other then file transfers!

Also of note, while READ IOPS is important, so is WRITE... maybe not AS important, but ill be damned if its still not important!



(*Disclaimer: in the tests I did, you will note that HD Tune shows the same performance in IOPS almost no matter what format/allocation unit size is selected, this is part of the reason I mentioned above that real world use/file size is important as actual IOPS performance fluctuates depending on the situation)

I hope this little post manages to help someone, or even confuses someone enough to actually ask questions, there's no better reason to ask a question if you are in doubt :P (unless its something common place... then theres the search funtion THEN ask HAR HAR HAR)



EDIT: SHAMELESS PUG: I am always trying to look for more cards to test (and am normally always too broke to purchase for myself), so If you happen to have one or a few or whatever and would like it benchmarked and added to my results folder (which will/should eventually become a nice spreadsheet, when i find someone to bully -read: beg- into making a nice one with pretty pictures and graphs), I will gladly accept them for testing (worded as such, when testing is finished, I can either add them to an ugly looking hot-glue piece of paper I have going or return it back to you, your choice), trust is of course a factor, so that's completely up to you if you want to take the risk, my only online transactions are through ebay and a few sale/purchases made over at the XDA marketplace, oh, and Craigslist. Needless to say, I dont plan on screwing anyone over, so if your first thought is that, then think no more thoughts, move along, these arent the droids your looking for.

[Sc/ant864]

I'm betting that the crappy cables are USB 1.0 and the good ones are 2.0 since you can't tell unless you label them. My laptop has 4 ports, 3 are 1.0, and one is 2.0, why they all aren't 2.0 at this point is beyond me, but the laptop continually will tell me to plug my phone into the 2.0 port if its not used. Just some food for thought.

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