SD Strange-results - or - How I learned to love CM7 on SD - Dec-11 results compiled!

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ewichern

Member
Jan 30, 2011
6
0
PNY 32GB class10 High Speed Micro SDHC P-SDU32G10-EFS2

Code:
-----------------------------------------------------------------------
CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
                           Crystal Dew World :
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

           Sequential Read :    18.336 MB/s
          Sequential Write :     7.198 MB/s
         Random Read 512KB :    18.059 MB/s
        Random Write 512KB :     0.598 MB/s
    Random Read 4KB (QD=1) :     2.775 MB/s [   677.5 IOPS]
   Random Write 4KB (QD=1) :     0.465 MB/s [   113.4 IOPS]
   Random Read 4KB (QD=32) :     2.217 MB/s [   541.3 IOPS]
  Random Write 4KB (QD=32) :     0.348 MB/s [    84.9 IOPS]

  Test : 50 MB [L: 8.1% (2.4/30.0 GB)] (x5)
  Date : 2012/05/09 17:15:12
    OS : Windows 7  SP1 [6.1 Build 7601] (x64)

ugh. Random writes could be a lot worse, but not great numbers overall.
 

zaggaza

Member
Nov 15, 2007
9
0
Ok. Read through 35 pages. Consensus Sandisk -- class 2 or 4. 8gb or 16gb? Depends on the card...

Is there an actual rationale for why this is so?:eek:
 

soobaerodude

Member
Oct 17, 2009
9
1
SanDisk Mobile Ultra UHS-I, class 10 microSD

The Samsung class 10 has a competitor, the SanDisk Mobile Ultra UHS-I, class 10 microSD!

SanDisk's description of the card

Benchmarks for the 32GB, item# SDSDQUA-032G-A11A, USB 2.0 reader connected to USB 3.0 port
Code:
           Sequential Read :    18.372 MB/s
          Sequential Write :    13.057 MB/s
         Random Read 512KB :    18.703 MB/s
        Random Write 512KB :     8.554 MB/s
    Random Read 4KB (QD=1) :     3.150 MB/s [   769.0 IOPS]
   Random Write 4KB (QD=1) :     1.957 MB/s [   477.8 IOPS]
   Random Read 4KB (QD=32) :     3.590 MB/s [   876.4 IOPS]
  Random Write 4KB (QD=32) :     1.960 MB/s [   478.5 IOPS]

  Test : 50 MB [D: 0.0% (0.0/29.7 GB)] (x5)
 
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leistungssurrogat

New member
May 7, 2012
4
3
64GB SanDisk Mobile Ultra UHS-I microSDHC Class 6

These are the results for the 64GB SanDisk Mobile Ultra UHS-I microSDHC Class 6 (SDSQY-064G-U46A) tested with the internal card reader of my notebook:

Code:
           Sequential Read :    20.111 MB/s
          Sequential Write :     8.460 MB/s
         Random Read 512KB :    19.676 MB/s
        Random Write 512KB :     2.405 MB/s
    Random Read 4KB (QD=1) :     2.794 MB/s [   682.1 IOPS]
   Random Write 4KB (QD=1) :     1.280 MB/s [   312.4 IOPS]
   Random Read 4KB (QD=32) :     3.660 MB/s [   893.6 IOPS]
  Random Write 4KB (QD=32) :     1.397 MB/s [   341.1 IOPS]
 

flatulatorx

New member
Mar 5, 2012
3
1
16GB Samsung Class 10 = epic fail

Having had such good experience with Samsung 32GB class 10's (see my previous 2 posts), I thought I'd give their 16GB card a try. It's marketed along with their esteemed 32GB class10, but rated at almost twice the write speed (21mb/s vs 13 mb/s). Turns out this extreme write speed pertains strictly to sequential writes.

So, I was in for a shock when I saw the large block random write speed, then nearly fainted at the sight of the small block random write speed. Ran the test twice to be sure.

-----------------------------------------------------------------------
CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
Crystal Dew World :
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 23.212 MB/s
Sequential Write : 20.712 MB/s
Random Read 512KB : 22.219 MB/s
Random Write 512KB : 2.152 MB/s
Random Read 4KB (QD=1) : 3.409 MB/s [ 832.2 IOPS]
Random Write 4KB (QD=1) : 0.024 MB/s [ 5.9 IOPS]
Random Read 4KB (QD=32) : 3.614 MB/s [ 882.4 IOPS]
Random Write 4KB (QD=32) : 0.042 MB/s [ 10.3 IOPS]

Test : 50 MB [H: 0.0% (0.0/15.1 GB)] (x5)
Date : 2012/06/27 17:34:12
OS : Windows 7 SP1 [6.1 Build 7601] (x64)
Samsung uSD 16GB class10 (Korea) Jun'12


(Tested straight out of retail pkg on a Sandisk Extreme Pro expresscard reader).


Looking back at previous tests of my various cards, I got similarly poor random write results with 2 other cards that also had very high (17mb/s or higher) sequential write speeds -- a Lexar 128GB SDXC class10 and a Sandisk Ultra uSD class4.

This is an admittedly small sample, but the moral of the story for me is that the premise that cards with high sequential write speed have low random write speeds is sort of true, but only for extreme sequential write speeds. You can still get good random write speeds with good (but not extreme) sequential write speeds (from top tier manufacturers at least).

Very interesting results from soobaerodude's Sandisk Ultra UHS-1 card. I'll have to give that one a try.
 
Last edited:

stolenmoment

Senior Member
Mar 27, 2011
360
43
I'm a bit reluctant to resurrect an old thread, but does anybody have stats like this for the internal emmc?

Or a native app that can be told to look at both?

Sent from my NookColor using xda premium
 
Dec 21, 2011
24
0
UT
I have not seen a native app that can test read/write speeds on Android, but I do know that because CDM is a Windows program it cannot test the emmc because it is not mounted as a logical drive when tethered to your computer.

From what I have gleened, the internal memory on any Android device would have to be unmounted from the device for your PC to mount it.

Sent from my NookColor using xda app-developers app
 

tonestertm

Member
Sep 21, 2011
20
10
Sandisk 32GB Class 10 UHS-1 SDSDQU-032G-AC11A

Sandisk 32GB Class 10 UHS-1 SDSDQU-032G-AC11A
Purchased at Costco. (Made in China)

CrystalDiskMark 3.0.1 (C) 2007-2010 hiyohiyo
-----------------------------------------------------------------------

Sequential Read : 14.015 MB/s
Sequential Write : 10.198 MB/s
Random Read 512KB : 14.094 MB/s
Random Write 512KB : 9.064 MB/s
Random Read 4KB (QD=1) : 2.978 MB/s [ 727.2 IOPS]
Random Write 4KB (QD=1) : 1.359 MB/s [ 331.9 IOPS]
Random Read 4KB (QD=32) : 2.923 MB/s [ 713.5 IOPS]
Random Write 4KB (QD=32) : 1.401 MB/s [ 342.0 IOPS]

This is a good representation of multiple tests on the card as new and after used for a (successful) test CM10 install then repartitioned/reformatted as a single partition.
 
Last edited:
Dec 21, 2011
24
0
UT
Purchased at Costco

CrystalDiskMark 3.0.1 (C) 2007-2010 hiyohiyo
-----------------------------------------------------------------------

Sequential Read : 14.015 MB/s
Sequential Write : 10.198 MB/s
Random Read 512KB : 14.094 MB/s
Random Write 512KB : 9.064 MB/s
Random Read 4KB (QD=1) : 2.978 MB/s [ 727.2 IOPS]
Random Write 4KB (QD=1) : 1.359 MB/s [ 331.9 IOPS]
Random Read 4KB (QD=32) : 2.923 MB/s [ 713.5 IOPS]
Random Write 4KB (QD=32) : 1.401 MB/s [ 342.0 IOPS]

This is a good representation of multiple tests on the card as new and after used for a (successful) test CM10 install then repartitioned/reformatted as a single partition.

What brand, class and size is that card?

Sent from my NookColor using xda app-developers app
 

tobydjones

Member
Jun 4, 2011
45
17

SacTappingUni

Senior Member
Aug 4, 2012
101
13
Bothell WA.
goo.gl
Anyone know if this applies to the cm10 builds available for the NC? I'm considering getting the aforementioned SD card now. I just want to make sure that it'll actually do what it's supposed to do.

Sent from my NookColor using xda app-developers app
 

leapinlar

Senior Member
Oct 18, 2006
8,873
3,878
Anyone know if this applies to the cm10 builds available for the NC? I'm considering getting the aforementioned SD card now. I just want to make sure that it'll actually do what it's supposed to do.

Sent from my NookColor using xda app-developers app

Yes, this applies to any ROM you want to put on SD. The card recommendations, that is.

Sent from my Nook HD+ using Tapatalk
 

tonestertm

Member
Sep 21, 2011
20
10
What brand, class and size is that ?

Sorry, I had typed it in, must have pasted over it. :( That's the Sandisk 32GB Class 10 card currently being sold at Costco. Don't have the complete model number with me at the moment. I'll edit it in later.

Edit: OK, that's weird... the info was there in the subhead the whole time, but for some reason it's not showing on my tapatalk...?
 
Last edited:
Dec 21, 2011
24
0
UT
Those are really good 4kb speeds for a class 10 card. SanDisk is definitely the best card for the CM on Nook.

Sent from my VS840 4G using xda app-developers app
 

tonestertm

Member
Sep 21, 2011
20
10
Those are really good 4kb speeds for a class 10 card. SanDisk is definitely the best card for the CM on Nook.

Sent from my VS840 4G using xda app-developers app

Yep, they do something right inside there. My wife and I have both been on SanDisk 16GB Class 6 (also from Costco--specs somewhere upthread) for about the last year, no complaints. :knocking wood:
 

drcameron

Member
Apr 12, 2012
17
2
G.Skill 16GB class 10 from newegg

Typical results from 2 cards as I am getting two new Nook tabs ready for Christmas. I took a gamble paying about $6.60 per card at Newegg. They are 16GB gskill class 10 cards. I'll have to see how the real performance goes. Benchmarks are below.

CrystalDiskMark 3.0.2 (C) 2007-2012 hiyohiyo
Test : 50 MB

Sequential Read : 19.802 MB/s
Sequential Write : 17.086 MB/s
Random Read 512KB : 19.415 MB/s
Random Write 512KB : 6.755 MB/s
Random Read 4KB (QD=1) : 3.877 MB/s [ 946.6 IOPS]
Random Write 4KB (QD=1) : 0.887 MB/s [ 216.6 IOPS]
Random Read 4KB (QD=32) : 4.201 MB/s [ 1025.7 IOPS]
Random Write 4KB (QD=32) : 1.338 MB/s [ 326.6 IOPS]
 
Last edited:

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  • 34
    1/16/2012 update: Thanks to waxhell for compiling all of the results in this thread (at least as of mid-december! OK, so I took a while to get this posted...)
    https://docs.google.com/spreadsheet/ccc?key=0AjPE3ZAD2eVudE9vZmQ3aHlfTkFvU2J4ZUplRDJQTEE

    5/20 update: SD card performance benchmark table by a.fenderson from later in this thread added at the bottom of this post. Thank you a.fenderson!
    ------------------
    April minor update with a Transcend SD (see http://forum.xda-developers.com/showpost.php?p=12964262&postcount=8)

    _________________________________________________

    Let me tell you my story.

    Over the last couple of months as I have mucked around with SD booting various flavors of froyo and, more recently, CM7, I have found it maddening that there are apparently so many people that LOVE those versions, even people that seemed to have the same SD card as the two I've tried.

    One of those is a Class 10 Patriot 8gig, which I've seen mentioned as an acceptable boot disk.
    The other is a Kingston Class 4 4gig that tests out as significantly slower than the Patriot, but didn't really run froyo any slower.

    Now I know I've seen posts that mention small block write speed as being important, but the numbers I've seen posted really didn't make me think the Patriot was the cause...
    ...the cause of FRUSTRATINGLY slow UI, where froyo (and CM7) seem to go off into lala-land for a few seconds every time I (tried to) do something.
    ...the cause of glacial web-surfing, where even downloading GOOGLEforchrissake takes forever. Of snail's-pace market downloads. Oh god.

    Every time I would give up and go back to Eclair and breath a sigh of relief, reveling in the snappiness, the zippy web-surfing, the rapid response of m.pornhub.com.

    And every time the siren song of the CM7-elite would call me back. THIS time I did something different. I saw mention that a Class 2, YES A FREAKING CLASS 2, Sandisk from costco worked well. So I skippity-skopped up and bought one.

    After backing up the Patriot and writing THAT VERY SAME img to the Sandisk (which, yes, took 3 times as long as writing to the Patriot), I booted CM7.

    OMG

    The heavens opened and the angels sang, I HAD ARRIVED IN THE PROMISED LAND!
    NOW I knew what the chosen had been praising! NOW I knew the joy that is CM7! ZIP-ZIP-ZIPPITY!

    HOLY CRAP?! How could a benchmark be so misleading? I HATE those bastard SD manufacturers, or maybe it's the industry group that chose such a sucky measure of speed.

    For your edification, here are some CrystalDiskMark (5 iterations, 50MB) results from 2 sucky cards and the good Sandisk.


    __Test_________________Sandisk 8G Class 2___Patriot 8G Class 10____Kingston Class4 4Gig
    Sequential Read :__________10.871 MB/s________20.036 MB/s___________18.700 MB/s
    Sequential Write :__________6.659 MB/s________13.660 MB/s____________4.277 MB/s
    Random Read 4KB (QD=32) :___3.077 MB/s_________3.444 MB/s____________2.088 MB/s
    Random Write 4KB (QD=32) :__1.791 MB/s________0.038 MB/s_____________0.016 MB/s


    Look at that, both the Kingston and the Patriot blow away or are close enough to the Sandisk in everything BUT....

    (wait for it)....

    SMALL BLOCK RANDOM WRITES
    where the Sandisk is FIFTY times the speed of the Patriot and ONE HUNDREDtimes the Kingston.

    Now you may say, "Swizzlenuts, old pal, I KNEW that."

    But for all you poor slobs who didn't, who are dragging yer sorry ass through the broken glass that is booting off of a slow SD (you know who both of you are), I hope this helps.

    And now you may commence posting links to specific posts where this info was discussed in detail last December.


    ------------------
    Thanks to all of the people that posted their results and to a.fenderson for compiling them. Here's his table from http://forum.xda-developers.com/showpost.php?p=13991898&postcount=144
    Code:
    POSTER         BRAND      CLASS  CAPACITY  4 KB RANDOM
                                      (GB)    WRITE QD32(MB/s)    NOTE
    swoozle        SanDisk        2    8          1.791           Model: SDSQ-8192-AC11M
    a.fenderson    SanDisk        4    16         1.660           SanDisk C4 16GB 1 of 2 cards
    MickMcGeough   SanDisk        4    8          1.59            benchmarked in XBench, QD unknown
    a.fenderson    SanDisk        4    16         1.500           SanDisk C4 16GB 2 of 2 cards
    Awats          SanDisk        4    16         1.391           SanDisk C4 16GB 1 of 2 cards ; fastest (onboard) reader
    arwild01       SanDisk        4    8          1.369    
    Awats          SanDisk        4    16         1.284           SanDisk C4 16GB 2 of 2 cards ; fastest (onboard) reader
    robot8         SanDisk        4    8          1.270           SanDisk C4 8GB 2 of 2 cards
    robot8         SanDisk        4    8          1.259           SanDisk C4 8GB 1 of 2 cards
    chinly43       SanDisk        4    16         1.257           (not via Nook) ; same card as chinly43's other listed SanDisk C4 16GB
    joobu          SanDisk        4    4          1.175    
    angomy         Nook internal  N/A N/A         1.116           via Nook on USB
    chinly43       Nook internal  N/A N/A         1.094           via Nook on USB
    a.fenderson    Transcend      2    32         1.032    
    a.fenderson    SanDisk        4    4          0.898    
    a.fenderson    SanDisk        2    4          0.891    
    pchoi94        SanDisk        4    16         0.834    
    chinly43       SanDisk        4    16         0.769           via Nook on USB ; same as chinly43's other listed SanDisk C4 16GB
    pryonix        SanDisk        4    8          0.625    
    chinly43       SanDisk        2    8          0.616    
    a.fenderson    SanDisk        4    8          0.596    
    angomy         SanDisk        4    16         0.574    
    Blue6IX        SanDisk        2    16         0.350    
    a.fenderson    SanDisk       N/A   2          0.269    
    Awats          SanDisk        4    2          0.261           SanDisk C4 2GB 1 of 2 cards ; fastest (onboard) reader
    Awats          SanDisk        4    2          0.236           SanDisk C4 2GB 2 of 2 cards ; fastest (onboard) reader
    pryonix        Samsung       N/a   2          0.093    
    victle         Kingston      N/A   2          0.051    
    victle         Dane-Elec     N/A   2          0.050           0.050 or less:  exact value unspecified
    joobu          Lexar          4    8          0.038    
    swoozle        Patriot        10   8          0.038    
    Blue6IX        Dane-Elec      4    4          0.037           (made in Japan)
    omghahalol     Transcend      6    16         0.037    
    Ravynmagi      Samsung(??)    2    4          0.037    
    pryonix        Kingmax        10   16         0.036    
    Ravynmagi      Wintech        10   16         0.036    
    victle         Transcend      6    4          0.034    
    omghahalol     Transcend      6    8          0.033    
    Ravynmagi      SanDisk        2    8          0.033    
    pryonix        Transcend      6    8          0.033    
    Ravynmagi      Patriot        10   16         0.030    
    Blue6IX        PNY            10   8          0.030    
    pchoi94        Kingston       2    16         0.030    
    swoozle        Transcend      6    8          0.029           Model: TS8GUSDHC6
    joobu          ??            N/A   2          0.029    
    chinly43       SanDisk       N/A   1          0.029    
    a.fenderson    SanDisk       N/A   1          0.028    
    victle         PNY            4    8          0.028    
    Blue6IX        PNY           N/A   2          0.027           (made in Taiwan)
    omghahalol     SanDisk        2    2          0.021    
    MickMcGeough   SanDisk        2    8          0.02           benchmarked in XBench, QD unknown
    robot8         Transcend      6    8          0.018           Transcend C6 8GB 1 of 2 cards
    ExploreMN      Patriot        10   16         0.018    
    arwild01       Samsung(??)    4    8          0.017    
    swoozle        Kingston       4    4          0.016           Model: SDC4/8GB
    Awats          Patriot        4    4          0.016           Patriot C4 4GB 1 of 2 cards ; fastest (onboard) reader
    robot8         Transcend      6    8          0.014           Transcend C6 8GB 2 of 2 cards
    Tnexus         Patriot        10   16         0.014    
    a.fenderson    Kingston       4    8          0.014    
    Awats          Patriot        4    4          0.011           Patriot C4 4GB 2 of 2 cards ; fastest (onboard) reader
    chinly43       Lexar          4    8          0.011
    6
    This thread should be pinned: specifically the list of cards and their bench results. I was amazed at what a difference changing my SD card made.

    I fear swoozle (the OP) may have abandoned us, but if not or if an admin who wants to sticky this thread could do so, I'd be glad for someone to copy and paste the list I keep updating to the end of the first post. Speaking of that:

    Code:
    POSTER		BRAND		CLASS	CAPACITY (GB)	4 KB RANDOM WRITE QD32 (MB/s)	NOTE
    swoozle		SanDisk		2	8		1.791	
    a.fenderson	SanDisk		4	16		1.660				SanDisk C4 16GB 1 of 2 cards
    MickMcGeough	SanDisk		4	8		1.59				benchmarked in XBench, QD unknown
    a.fenderson	SanDisk		4	16		1.500				SanDisk C4 16GB 2 of 2 cards
    Awats		SanDisk		4	16		1.391				SanDisk C4 16GB 1 of 2 cards ; fastest (onboard) reader
    arwild01	SanDisk		4	8		1.369	
    Awats		SanDisk		4	16		1.284				SanDisk C4 16GB 2 of 2 cards ; fastest (onboard) reader
    robot8		SanDisk		4	8		1.270				SanDisk C4 8GB 2 of 2 cards
    robot8		SanDisk		4	8		1.259				SanDisk C4 8GB 1 of 2 cards
    chinly43	SanDisk		4	16		1.257				(not via Nook) ; same card as chinly43's other listed SanDisk C4 16GB
    joobu		SanDisk		4	4		1.175	
    angomy		Nook internal	N/A	N/A		1.116				via Nook on USB
    chinly43	Nook internal	N/A	N/A		1.094				via Nook on USB
    a.fenderson	Transcend	2	32		1.032		
    a.fenderson	SanDisk		4	4		0.898	
    a.fenderson	SanDisk		2	4		0.891	
    pchoi94		SanDisk		4	16		0.834	
    chinly43	SanDisk		4	16		0.769				via Nook on USB ; same as chinly43's other listed SanDisk C4 16GB
    pryonix		SanDisk		4	8		0.625	
    chinly43	SanDisk		2	8		0.616	
    a.fenderson	SanDisk		4	8		0.596	
    angomy		SanDisk		4	16		0.574	
    Blue6IX		SanDisk		2	16		0.350	
    a.fenderson	SanDisk		N/A	2		0.269	
    Awats		SanDisk		4	2		0.261				SanDisk C4 2GB 1 of 2 cards ; fastest (onboard) reader
    Awats		SanDisk		4	2		0.236				SanDisk C4 2GB 2 of 2 cards ; fastest (onboard) reader
    pryonix		Samsung		N/a	2		0.093	
    victle		Kingston	N/A	2		0.051	
    victle		Dane-Elec	N/A	2		0.050				0.050 or less:  exact value unspecified
    joobu		Lexar		4	8		0.038	
    swoozle		Patriot		10	8		0.038	
    Blue6IX		Dane-Elec	4	4		0.037				(made in Japan)
    omghahalol 	Transcend	6	16		0.037	
    Ravynmagi	Samsung(??)	2	4		0.037	
    pryonix		Kingmax		10	16		0.036	
    Ravynmagi	Wintech		10	16		0.036	
    victle		Transcend	6	4		0.034	
    omghahalol 	Transcend	6	8		0.033	
    Ravynmagi	SanDisk		2	8		0.033	
    pryonix		Transcend	6	8		0.033	
    Ravynmagi	Patriot		10	16		0.030	
    Blue6IX		PNY		10	8		0.030	
    pchoi94		Kingston	2	16		0.030	
    swoozle		Transcend	6	8		0.029	
    joobu		??		N/A	2		0.029	
    chinly43	SanDisk		N/A	1		0.029	
    a.fenderson	SanDisk		N/A	1		0.028	
    victle		PNY		4	8		0.028	
    Blue6IX		PNY		N/A	2		0.027				(made in Taiwan)
    omghahalol 	SanDisk		2	2		0.021	
    MickMcGeough	SanDisk		2	8		0.02				benchmarked in XBench, QD unknown
    robot8		Transcend	6	8		0.018				Transcend C6 8GB 1 of 2 cards
    ExploreMN	Patriot		10	16		0.018	
    arwild01	Samsung(??)	4	8		0.017	
    swoozle		Kingston	4	4		0.016	
    Awats		Patriot		4	4		0.016				Patriot C4 4GB 1 of 2 cards ; fastest (onboard) reader
    robot8		Transcend	6	8		0.014				Transcend C6 8GB 2 of 2 cards
    Tnexus		Patriot		10	16		0.014	
    a.fenderson	Kingston	4	8		0.014	
    Awats		Patriot		4	4		0.011				Patriot C4 4GB 2 of 2 cards ; fastest (onboard) reader
    chinly43	Lexar		4	8		0.011
    4
    Hi,

    I'm getting my nook next week, and I'm trying to pick an SD for it. I initially wanted an 8GB Class 6 Adata, but they're quite difficult to get a hold of in the UK.

    I'm torn between a SanDisk Class 4 and a Samsung Class 6. Both are 8GB.

    Anyone got any experience with Samsung or should I still to the tried and tested SanDisk?

    edit: I managed to find somewhere with a Class 6 Adata, so that's still an option.

    Any advice would be much appreciated.

    Will you be running your Android install off the SD card, or just using it for data?
    If just data, you'll be fine for most applications.

    I benchmarked several brand-new SanDisk cards of varying capacities, and all the >= 4 GB cards were Class 4, but even so it was hit-or-miss: random 4K writes for the 1 and 2 GB cards sucked, the 4 GB card was decent, the 8 GB card was half as fast as the 4 GB, one of the 16 GB cards looked great, and the other had kind of inconsistent results. So even within the same brand (and class rating where applicable), there is a lot of variation, unfortunately. You might look below and narrow your purchasing options down to those combinations of brand, size, and Class whose 4K random writes are shown to be around 1.00 MB/s or better, though really there are two orders of magnitude difference between the truly crappy cards and the best ones, so even cards with 0.1 to 0.9 MB/s 4K random writes might suffice when compared to the 0.0X cards. In general, so far it looks like SanDisk Class 4 and 2 vary between good (~.5 MB/s) and excellent (~1.5 MB/s), though unclassed SanDisk aren't so great.

    If running CM7 (etc) off it, my best advice is to test whatever card(s) you do end up buying with CrystalDiskMark and only using it as your boot disk if the 4K random writes are approximately equal to or greater than 1.00 MB/s.

    @all: the anecdotal reports of your cards running well are great, but if you have the time, please benchmark your cards with CrystalDiskMark so that we can all get enough data to be more confident in our card purchases. If you're worried about AV warnings when you download, please see this post where I explained what the opencandy component of the installer does and does not do (it's not malware). Also, along with your benchmarks, please provide your evaluation of how well the card runs your ROM, etc, if applicable.

    Here's a compilation of the actual benchmarking data thus far in this thread (with the only benchmakred data presented as 4 KB random write w/ QD=32, since this is the only commonality among all posters). It's been sorted (descending) on the write speed column:

    Code:
    POSTER		BRAND		CLASS	CAPACITY (GB)	4 KB RANDOM WRITE QD32 (MB/s)
    swoozle		SanDisk		2	8		1.791
    a.fenderson	SanDisk		4	16		1.660
    a.fenderson	SanDisk		4	16		1.500
    robot8		SanDisk		4	8		1.259
    chinly43	SanDisk		4	16		1.257
    joobu		SanDisk		4	4		1.175
    angomy		Nook internal	N/A	N/A		1.116
    a.fenderson	Transcend	2	32		1.032
    a.fenderson	SanDisk		4	4		0.898
    chinly43	SanDisk		2	8		0.616
    a.fenderson	SanDisk		4	8		0.596
    angomy		SanDisk		4	16		0.574
    a.fenderson	SanDisk		N/A	2		0.269
    swoozle		Patroit		10	8		0.038
    joobu		Lexar		4	8		0.038
    swoozle		Transcend	6	8		0.029
    joobu		??		N/A	2		0.029
    chinly43	SanDisk		N/A	1		0.029
    a.fenderson	SanDisk		N/A	1		0.028
    robot8		Transcend	6	8		0.018
    ExploreMN	Patroit		10	16		0.018
    swoozle		Kingston	4	4		0.016
    Tnexus		Patroit		10	16		0.014
    a.fenderson	Kingston	4	8		0.014
    chinly43	Lexar		4	8		0.011
    2
    Thanks a lot for clarifying, I will try it out now that I know I can opt out of the install.

    Edit: Ran CrystalDiskMark for 16GB class 4 Sandisk card vs internal nook storage via USB storage mode:

    Sandisk 16GB class 4 (non-Ultra+)

    Sequential Read : 20.003 MB/s
    Sequential Write : 3.086 MB/s
    Random Read 512KB : 20.113 MB/s
    Random Write 512KB : 1.372 MB/s
    Random Read 4KB (QD=1) : 5.143 MB/s [ 1255.7 IOPS]
    Random Write 4KB (QD=1) : 0.594 MB/s [ 145.1 IOPS]
    Random Read 4KB (QD=32) : 6.019 MB/s [ 1469.4 IOPS]
    Random Write 4KB (QD=32) : 0.574 MB/s [ 140.1 IOPS]


    Nook internal:

    Sequential Read : 19.970 MB/s
    Sequential Write : 3.937 MB/s
    Random Read 512KB : 20.634 MB/s
    Random Write 512KB : 2.173 MB/s
    Random Read 4KB (QD=1) : 4.905 MB/s [ 1197.5 IOPS]
    Random Write 4KB (QD=1) : 1.106 MB/s [ 270.0 IOPS]
    Random Read 4KB (QD=32) : 4.446 MB/s [ 1085.4 IOPS]
    Random Write 4KB (QD=32) : 1.116 MB/s [ 272.4 IOPS]
    2
    Update:Transcend

    Just a minor addition with a Transcend card. I'd seen many posts that swore by a Transcend Cl 6 8G card through Newegg. I ordered, received, benchmarked and loaded CM7 Nightly 37.
    To cut to the chase, the Transcend sucked big hairy monkey balls. Similar small block write speeds as the other crappy cards. And the CM7 performance was predictably bad. Crappy UI response and FCs.

    __Test_________Sandisk Cl2 8G___Patriot CL10 8G____Kingston Cl4 4Gig___Transcend Cl6 8G
    Sequential Read___10.871 MB/s____20.036 MB/s___________18.700 MB/s___________19.930 MB/s
    Sequential Write___6.659 MB/s____13.660 MB/s____________4.277 MB/s___________19.325 MB/s
    Rndm Rd 4KB(QD32)__3.077 MB/s_____3.444 MB/s____________2.088 MB/s___________2.968 MB/s
    Rndm Wrt 4KB(QD32)_1.791 MB/s_____0.038 MB/s____________0.016 MB/s___________0.029 MB/s

    I'm sure any of these would work fine as data cards. But for running off of SD, it makes a huge difference.