Database Users

2 GB MMC card

Hi All
I have seen that the new 2GB MMC 4 card has been released by Pretec?
It is ment to be the fastest flash memory in the world. hear are the speeds:
Read: 22.5MB/s
Write: 18MB/s
Does any one know if this new MMC 4 cards will work in our XDA II's it says it should work in most SD/MMC slots around today... but regarding speed do you know if we would see any speed increases from SD with this new MMC???
http://www.pretec.com

from tests at least with sd cards the xda2 dont handle all that well compare to most other pocketpc's also worse then xda1 which dont use
the poor internal sd interface that xcale have
you can benchmark using pocketmechanics
and try doing a search people have been posting benchmarks they made with the xda series

Thanks for the reply Rudegar...
Does any one else know any info on the new MMC 4 cards???

well i would asume that they should work
but are they not a bit on the expensive side ?
i mean even with the extre speed if it would help
their price are pretty high
compared to some a few 256MB sd cards
and i dont have any serious issues even with my really really really
slow sandisk sd cards

Die MMC 4 Standard defines 4bit in parallel for data-transmission while AFAIK the MMC has only 1 bit data serial for data.
So it is likely, that it will not work.
Alex

but i'm pretty sure that sd also use 4bit in parallel
but i think the problem with the xda2 is that it's internal xcale interface is a mmc interface which is compatible with sd not the other way around
this is also one of the reasons the xda2 have a slower sd interface then xda1 where it have an external chip because the arm200 dont have that mmc internal interface like xcale400

So MMC are not necessary slower than SD?
Hi...
after reading about the new pretec card I went back to read the articles/posts regarding the difference between MMC and SD...
http://asia.cnet.com/reviews/handhelds/0,39001709,39008492-2,00.htm
http://forum.xda-developers.com/viewtopic.php?t=7901&start=0
http://forum.xda-developers.com/viewtopic.php?t=5513&highlight=sd+mmc
So, if I undestand well now, MMC are not necessary (by definition) slower than SD (this Pretec is faster than the Panasonic?) and not necessary smaller than SD... the only difference boils down to the SD feature...
Rudegar (first all thank you for all the help you are giving in this forum... you are of great example! :wink: ) what do you use your SD card for? In particular, do you watch compressed movies on your XDA without any problems in term of speed?
Finally on SD vs MMC...:
-why do u think Pretec made the 2GB card MMC instead of SD?
-why do you think expansys is pricing MMC higher than SD (look at 256 and 1GB)
http://www.expansys.com/d_storage.asp
so it is not even true that MMC are cheaper than SD...
Mentioning Expansys... what are the best places on the web:
-with widest variety (expansys has recently cut a lot... there are no Panasonic etc... anymore...)
-with the past price (I want to buy one finally!!!)
Thanks,
Chris

i use my sd card mainly for music and a few programs that eat too much space and ebooks and a few video's mainly to brag
in terms of speed then i sometimes get nonsync audio on larger video clips
and when i tried journalbar i had sound clickings so i had to turn it off to listen to music (but i'm not 100% sure that was because of sd speed and not just journalbar acting strange)
and then of cause i use my sd for getting files from a pc that dont have a cradle or other sync cable
using the sandisk cruzer if it dont have a sd reader already

I find my battery goes down much faster with the 256Mb SD card plugged in - would a faster 2Gb MMC card require more power, 1. for higher transfer speeds and 2. for keeping powered up?

Thank you Rudegar!
Good point Madkat...
maybe some with a 1GB memory card who has tried the 256 before can answer us... but I think it would be easier if you open a new thread... something like "SD Card bigger = more power consuption?"

hmmm well. i am expecting my new xda 2 on sunday was thinking of gettin a new mmc on it. whts the max. it supports plz confirm. also whts the standard memory on the phone itself.

I have 128MB, 256MB, 512MB and 1GB SD cards. While I do not have any empirical data to prove it, I do not see any difference in battery consumption between any of the cards. BTW - I have 32, 64 and 128MB MM cards as well.

BRosenow: Any chance you could do a little testing, like leaving MMC & SD cards of same capacity in overnight, and a high capacity SD overnight, and checking the new battery % in the morning? Would be greatly appreciated

I'll give it a go and let you know what I have discovered in a couple of days!

How did the testing go?
How did you go with your testing BRosenow??
Cheers!

Thanks for reminding me. My testing was inconclusive, but there does not seem to be any consistent difference in power drain between the different sizes of SD/MMC cards.
I used the same procedures each night - when I got home from work I put my imate in the cradle to be sure it was powered up to 100%. At 10:00PM I inserted the SD/MMC card and soft-reset the device then placed it on the desk beside my laptop. At 6:00AM I turned on the device and read the meter (using the battery meter in SPB Pocket Plus 2.0) and recorded the % of battery power remaining. My first tests were as follows:
1GB SD 89%
512MB SD 92%
256MB SD 91%
128MB SD 86%
64MB MMC 89%
I was interested to see if the same card consumed the same amount of power each time, so I tried my 1GB SD again, and this time 91% was remaining in the morning.
Other things have kept me from continuing the testing, but my conclusion is that battery drain is not linear based on expansion memory size or type and is influenced by unknown factors, but the precision of the Pocket Plus battery meter could certainly be a factor.
Thoughts?

try leaving it in fligth mode
since variations in signal str's can cause more or less
power requirements depending on how much work the
gsm part is doing that night

I can see that your suggestion is a good idea, though I do not think it would make an appreciable difference in the outcome. A total spread of 6% with the given test parameters, particulary given that a distinct trend was not obvious, does not lend itself to indicate a practical difference in power consumption between types of cards or size of cards. (IMHO )

yeah i just talked about one way to make it a tiny bit less unpredictable
5% is always called the stat error margin and 6% is soo close i doubt there is any relation because size and power requirements
maybe the result would differ a bit if the card were being access'd
not sure doubt there is a world of difference because
these types of cards are used in a world of devices where many i'm sure have amp limiters on their sd power curcit to make sure that a camara malfuction would not kill the sd card
so if like a 512MB card required that much more power then a 64MB card
then many cam's mp3players and ..... would be incompatible with those larger cards

Agreed.
I was tempted to write a little script/batch file that would access a file stored on the card at regular intervals, but I just cannot conceive that there will be a measurable difference, so I didn't bother.
At this point I believe that access times are a more important decision variable in which type/size/brand of card to buy than is power consumption.

Memory card writing slow: is this normal?

I have a question about MiniSD card writing slow:
I formated my card recently. now I'm trying to put data on it (about 700mb)
and it is taking longer than 3 hours and counting. I have written about 300mb so far.
Is this normal?
Is there software that can format the card in a way that it would write faster?/ or is this normal?

S.V.I said:
I have a question about MiniSD card writing slow:
I formated my card recently. now I'm trying to put data on it (about 700mb)
and it is taking longer than 3 hours and counting. I have written about 300mb so far.
Is this normal?
Click to expand...
Click to collapse
Yes.
Is there software that can format the card in a way that it would write faster?/ or is this normal?
Click to expand...
Click to collapse
No. Use an SD Card reader to load your card, then put it in the phone. That is the only fast way to do it. They are cheap (usually around $10 US), and totally worth it if, like me, you use your phone as a media player.
You are effectively asking the phone to read the file you send, copy it, then paste it into the SD Card. There is NO direct throughput, regardless of logic. Sorry to bear the bad news.

i was using the latest version of WM5storage.
formated the card with XP. then i tried a warez program to format it again. Pocket mechanic could not format it by the way.
anyway, just wanted to see if this was a usual thing. The card has pretty much become part of my phone; I lost the adapter that comes with it. I mostly use it to store cab files and photos in between flashing.
The main thing I noticed is that programs dont behave as well if put on storage card. I thought if there is a way to format it propperly, they might?
Thanx for your reply. glad to know i didnt kill my ca with XP.

Defragmentation error - lost clusters

I have Wizcode Defragment and ScanDisk on my HD2, nearly every time that I defrag I get an error message stating 'Errors were found on volume "storage card". The volume cannot be defragmented. Please check the volume for errors first and try defragmenting again'.
I then run ScanDisk which finds a number of invalid/lost clusters, yesterday there were over 200 lost clusters and today 27.
Is this anything to be concerned about? If so, what steps should I take to remedy?
Thank you for your assistance.

u defrag the Storage Card while it's in your HD2?

denizenx said:
u defrag the Storage Card while it's in your HD2?
Click to expand...
Click to collapse
Yes. With Wizcode Defragment Mobile I do not think there is an alternative.

defrag ing your sd card will reduce its life fairly significantly.flash memory has a limited number of write cycles, so defragmenting will use up quite a significant number of these cycles.
but more to the point .... my card always comes up as containing errors whenever I put it in my pc card reader, and asks if I want to fix it. it has been doing this for around 2 years and I've always chosen no, and never had any issues.

samsamuel said:
defrag ing your sd card will reduce its life fairly significantly.flash memory has a limited number of write cycles, so defragmenting will use up quite a significant number of these cycles.
but more to the point .... my card always comes up as containing errors whenever I put it in my pc card reader, and asks if I want to fix it. it has been doing this for around 2 years and I've always chosen no, and never had any issues.
Click to expand...
Click to collapse
Thank you for your reply. I was not aware that defraging a card reduced its life.

no worries.
don't lose any sleep over it,I believe the rewrite cycles are somewhere in the region of 10,000 cycles, so one or two defrags is neither here nor there, but I know how addictive de fragging can be, so doing the whole card even once per week will soon mount up.
personally if I were you and you are worried, I'd use the pc to scan and fix the card.

yeah forget about dragging your card.
get a kettle and a card reader.
copy thee contents of the card to your pc (in a new folder some where)@ put the kettle on while its copying. when is done format your card copy the contents back again to your nice shiney clean card. go make a cup of tea while they are copying back
the card will now be defragged

Apart from being a little harmful, defragmenting flash memory is also useless as there are no moving parts to suffer from fragmentation.

right
I concur. Defragging volumes on solid state media, like anything other than conventional harddisks, is not in any way contributing in any practical performance increase.
There are some benchmark tools for winmo out there. Just wait untill your card is realy fragged, run the benchmark, defrag, and run the test again. You will see no performance increase.
As stated, it's the moving parts that hate fragmented volumes, your HD2 has none, beside the buttons when you press them.
You shouldn't bother.
You should however get a solid state drive (SSD) for your desktop or laptop. It'll make you happy.
Broke, but happy.
(Check tests on internet, there is quite a lot difference between SSD's)
Best to spend that time researching performance of different SD cards. I for instance am very content with my 8 GB Transcend SDHC, some kind of superspeed series. It writes allmost 20MB/s in my desktop cardreader.
Nice.
It realy doesn't care what part of the 8 GB it needs to access to get you your file. I think I saw some article stating the difference is measured in µs. I don't think you can notice µs's, even when they bring their entire family of µs's.
Research tweaking cache sizes and pagepool. Might help with performance, depending on how you use your device.
Hope this helps.

Thank you all for your helpful advice.

HD2 destroyed my SD card?

Hello.
After trying the android booting, for 5-6'th time (all working), now the phone can't see the SD card. I thought it was only on the phone, but when i insert the card, in adapter and connect to pc, then NOTHING happens. Like if the card wasn't there.. Hmm, any clue? Usually I just formatted. But now, I can't format a SD card which "isn't there."
Please.

any one??? :S

mooooooa said:
Hello.
After trying the android booting, for 5-6'th time (all working), now the phone can't see the SD card. I thought it was only on the phone, but when i insert the card, in adapter and connect to pc, then NOTHING happens. Like if the card wasn't there.. Hmm, any clue? Usually I just formatted. But now, I can't format a SD card which "isn't there."
Please.
Click to expand...
Click to collapse
Sounds like your sd card maybe corrupt, they can die for no apparent reason, its happen to me twice in about 4yrs, tho i always buy from CEX they offer a 1yr warranty & just replace it if its within that time.
There's been a few threads about this;
http://forum.xda-developers.com/showthread.php?t=712281
http://forum.xda-developers.com/showthread.php?t=646731

Which brand?
mooooooa said:
Hello.
After trying the android booting, for 5-6'th time (all working), now the phone can't see the SD card. I thought it was only on the phone, but when i insert the card, in adapter and connect to pc, then NOTHING happens. Like if the card wasn't there.. Hmm, any clue? Usually I just formatted. But now, I can't format a SD card which "isn't there."
Please.
Click to expand...
Click to collapse
What is the brand of the memory card?

hey dude,i got the same problem as yours few days ago..cant do much abt it,i just buy a new one..some says the htc that makes the sd card problem

Hi,
My 8 GB sd card lags when i`m scrolling in the file manager.
In addition, the sd card drains the HD2 battery. I loose 35% in 6 hours in flight mode, but only 4% when not in flight mode without the sd card... ( this also yields for the original sandisk 2 GB sd card that was supplied with the phone).
Anyone experienced the same issue?
Is this hardware or software related, and can i fix this myself?

Error check your microSD card using your computer then switch your phone off, put the card back in it and switch your phone back on. The phone will need to index your music/video files etc so go to the relevant tabs and let it do its stuff. See how that helps.

mooooooa said:
Hello.
After trying the android booting, for 5-6'th time (all working), now the phone can't see the SD card. I thought it was only on the phone, but when i insert the card, in adapter and connect to pc, then NOTHING happens. Like if the card wasn't there.. Hmm, any clue? Usually I just formatted. But now, I can't format a SD card which "isn't there."
Please.
Click to expand...
Click to collapse
i got a new HD2 and it came with a MicroSD card. I put a couple of cooked ROMs on it and everything was fine for about a week and then the card jsut stopped working. I didnot use it on any other phone or on my PC and it just died.
I own an HTC Hero as well and i put the card in it but it wouldnt recognize it. It has never happened to me before. Never has a card died on me.
I think its a problem with the way the HD2 accesses the SDcard. I wouldnt know specifics but this is the first phone that fried my SD card.

Hey guys, I had the same issue. The SD card stopped working and cannot be formatted now via computer.

My experience with Windows Mobile is that the SD/CF driver is the weakest link. The problem seems to be simultaneous accesses drive it bonkers. I've had the disappearing card problem on other PDAs but usually removing it, doing a reboot with it out, and then inserting it after the reboot is complete will fix it. If it doesn't show up immediately DON'T do anything for a while, it could be doing a CHKDSK on the card, and if you mess with it it will screw it up worse.
Once it shows up what I would recommend is hooking up via USB in CF Disk mode (not Activesync) and doing a format on the drive from Windows.
Last night I got a new 32gb Class 4 MicroSD from China (unnamed) and stuck it in, worked fine, so I backed up all my data to my 'puter off the T-Mobile Class 2 16gb and changed to the new 32gb SD. I started the copy and after a while went to bed.
This morning I got up and it had died during the copy. It was giving me an error on the new MicroSD. It had copied about 75% but was asking to continue or skip. I ended up having to cancel it because it appeared full but it was not. After a reboot I found a ton of FILEXXX.CHK files which indicated it was doing a chkdsk.
Looking at it with SoftWinter.com's Storage Tools the disk was formatted with 512 byte cluster size, way too small for such a large disk, so it was not really out of space just out of cluster nodes. If you have lots of files (I had 10,000) each takes up at least one, even if the file is only 5 bytes. So I reformatted it from the 'puter to 32k cluster size and started the copy over. Seems to be working better now.
Please note that using larger cluster size also will help performance when writing and reading large files as it has to do less directory accesses. Small cluster size is good if you have a lot of small files as it doesn't waste as much space. You lose on average 1/2 the cluster size for each file, as the last node is almost never full.

mknewman said:
My experience with Windows Mobile is that the SD/CF driver is the weakest link. The problem seems to be simultaneous accesses drive it bonkers. I've had the disappearing card problem on other PDAs but usually removing it, doing a reboot with it out, and then inserting it after the reboot is complete will fix it. If it doesn't show up immediately DON'T do anything for a while, it could be doing a CHKDSK on the card, and if you mess with it it will screw it up worse.
Once it shows up what I would recommend is hooking up via USB in CF Disk mode (not Activesync) and doing a format on the drive from Windows.
Last night I got a new 32gb Class 4 MicroSD from China (unnamed) and stuck it in, worked fine, so I backed up all my data to my 'puter off the T-Mobile Class 2 16gb and changed to the new 32gb SD. I started the copy and after a while went to bed.
This morning I got up and it had died during the copy. It was giving me an error on the new MicroSD. It had copied about 75% but was asking to continue or skip. I ended up having to cancel it because it appeared full but it was not. After a reboot I found a ton of FILEXXX.CHK files which indicated it was doing a chkdsk.
Looking at it with SoftWinter.com's Storage Tools the disk was formatted with 512 byte cluster size, way too small for such a large disk, so it was not really out of space just out of cluster nodes. If you have lots of files (I had 10,000) each takes up at least one, even if the file is only 5 bytes. So I reformatted it from the 'puter to 32k cluster size and started the copy over. Seems to be working better now.
Please note that using larger cluster size also will help performance when writing and reading large files as it has to do less directory accesses. Small cluster size is good if you have a lot of small files as it doesn't waste as much space. You lose on average 1/2 the cluster size for each file, as the last node is almost never full.
Click to expand...
Click to collapse
Hey
i hope for your sake im wrong, but as far as ive been able to find out in my own searching, only san disk has released a 32gb micro sd & its only class 2.
there has been a lot of talk of fake 32gb micro sd's from china, most are actually 4gb re-programed to read as 32gb on your phone or pc, but when you start to fill them with files more than their actual capacity they will only overwrite prev' files & become corrupt.
i actually pick up 1 (32gb) last weekend from a local store, tried to copy the contents of my 16gb, 7gb copied then an error occurred, 2nd attempt 9gb copied but files unreadable by phone or pc, fortunately i always buy from this store & they refunded (£50), straight away, still have 2 16gb cards ive had for about 9mnths with no probs.
there is another longer thread over in the Q&A section, you guys may find some useful feed back over there: http://forum.xda-developers.com/showthread.php?t=646731

Well, the one I got says SanDisk and I have done a full format and surface analysis, it checks out, but I am having trouble writing to it. Not sure what is up with it right now. I knew it was a fake but I thought it was a real fake, not a piece of junk. I hope you are wrong.

I´ve got problems too. I have two SanDisk 16 GB microSDHC cards and both of them are giving similar problems.
I´ve got my HD2 a few days ago and initially I used my old 16 GB card I bought with the X1 (then used with my TP2 and latest the HD2). Everything was working fine initially but then the problems arose. Now I have those problems:
1. Audio Manager has problems reading my music library. iPlay can read it though. Windows Media Player takes a long time building my music library but manages to do that eventually.
2. HTC Album can read my albums sometimes - sometimes not.
3. Resco Photo Manager can read the albums but sometimes it takes a long time to do it.
4. The computer can access the card without any problems after formatting and it seems not to be any problems reading or writing files to it. Installations of cabs stored on the memory card works.
5. Total Commander can access the card without any problems but takes slightly longer time than before to show all folders.
6. Running chkdsk in Windows gives the result of a perfectly working card.
7. The phone is draining battery in an abnormal way with the card inserted.
8. Flashing ROMs from the card worked initially but not any longer. Now it shows the threecolor bootloader screen instead.
The interesting thing is the fact both of my 16 GB cards has the exactly the same symptoms. I will try them in my X1, TP2 and Vivaz later to check out their behaviour.
When I inserts my old 8 GB card (everything made by SanDisk) everything works without any problems. Flashing ROMs work normally etc.
I´m running the Omega XT 3.0 and are using HardSPL3. The 16 GB card has worked perfectly initially with this ROM and HSPL so I don´t think they are related.
The whole thing seems to indicate some kind of "incompatibility" between the phone and the 16 GB cards. It´s like it is unable to handle that size of card correctly. It seems like it "trashes" the file system. My older 16 GB card started to behave badly which caused me to buy a replacement and now that replacement has the exactly the same behaviour.
My 8 GB card is an "ultra" SanDisk card. The troublesome cards are Class 2 cards. I began to have the impression the problem is some kind of issue with Class 2 - because the cards itself seems to be working after formatting.
I have formatted them with either Panasonic SDFormatter and the Format SD application on the phone. Both options gives the same result.

No need to format your SD card any more.

Do not format you SD card, in this way you will loose all your data.
You just need to Defragment you SD card and in this case you will never loose your data but also you will found that your SD card is back to High speed.
Defragmentation can be done using any windows just right click on your SD card then go to tools tab then click on defragment.

Interesting.....
Things never get fully deleted off SD cards anyway...

part of the sd tech is something called wear leveling..
doing a defrag on your memory card is not going to be very accurate.
the card has an on board chip that spreads out the writing of sectors to keep them from wearing out. this is transparent to the system.
Do not defrag a memory card. This consumes write/erase cycles and shortens the MTBF.

aarons6 said:
part of the sd tech is something called wear leveling..
doing a defrag on your memory card is not going to be very accurate.
the card has an on board chip that spreads out the writing of sectors to keep them from wearing out. this is transparent to the system.
Click to expand...
Click to collapse
I tried it on my HD2 and it works, and booting Android come faster as if i format it.
Defragment : it reorganize all the blocks in the SD card (re addressing the blocks)
which make running or opening a file is faster and it give more space.
It only effect on SD card files and not Android system files.
Android system files are found in data.img which is a virtual disk (Formatted as EXT2)

zaidsa3sa3 said:
I tried it on my HD2 and it works, and booting Android come faster as if i format it.
Defragment : it reorganize all the blocks in the SD card (re addressing the blocks)
which make running or opening a file is faster and it give more space.
It only effect on SD card files and not Android system files.
Android system files are found in data.img which is a virtual disk (Formatted as EXT2)
Click to expand...
Click to collapse
yes but because of the write leveling circuit those files are not organized contiguous in the first place.
they are placed in order of what sectors get written to less.
or at least thats how its supposed to work

But, the data.img is one big file on your sd card...
I could see doing a defrag once in a long while, like if you load up with a bunch of MP3s you plan on leaving there. But, if you constantly move files on & off, and defrag often, then you're just wearing your card out faster.

I thought defragmentation was only effective on hard drives?

aarons6 said:
yes but because of the write leveling circuit those files are not organized contiguous in the first place.
they are placed in order of what sectors get written to less.
or at least thats how its supposed to work
Click to expand...
Click to collapse
Try it before you judge
Am pretty sure of what i am talking about.

I think its better on your card to just copy everything on your card to your computer, then format card and copy everything back at once. I thing defragging causes too much writing and erasing on the sectors... it will make your card wear out quicker.
Sent from my HTC HD2 using XDA App

Defrag is only good for harddisk to save seektimes and minimize head movement
on a SD Card is nothing like that, no head that must seek thing.
There is no need to defrag SD Cards or SSD Disks

Quick format : it only clear the address table and it will not rearrange the blocks.
Defragmet is similar to full format but it is much faster and without loosing your data.
For me i will go to Defragment option.
BTW SD card doesn't have a read/write head that may scratch the cylinder (Harddisk),
it is a 0/1 operation (no mechanical parts) so it will not brick your SD card.
"SD card lifetime is 10 years or more."

ByteFax said:
Defrag is only good for harddisk to save seektimes and minimize head movement
on a SD Card is nothing like that, no head that must seek thing.
There is no need to defrag SD Cards or SSD Disks
Click to expand...
Click to collapse
It will reallocate the blocks in the sectors which will put all related blocks in sequence, which will make running an application faster with more free space on your sd card.
Try it and read about it before you judge.

Can you tell me where did you find that kind of info? I thought you shouldnt defragment sd cards and ssd drives. That just doesn't sound right to me...

100% correct.
ByteFax said:
Defrag is only good for harddisk to save seektimes and minimize head movement
on a SD Card is nothing like that, no head that must seek thing.
There is no need to defrag SD Cards or SSD Disks
Click to expand...
Click to collapse
Sent from my HTC HD2 using XDA App

The normal reason people suggest formatting your SD card is so that you can select a larger cluster size, to help with R/W speed and therefore battery life.
A defrag doesn't do this (obviously), so there will be times where a format is definitely the right thing to do.

zaidsa3sa3 said:
It will reallocate the blocks in the sectors which will put all related blocks in sequence, which will make running an application faster with more free space on your sd card.
Try it and read about it before you judge.
Click to expand...
Click to collapse
Can you tell me the access time of a Hard Drive and the one from a SD card?

Access time of a HDD is usually ~9ms-~11ms depending on the size, rotation speed and make. SD/SSD's usually have access times below 0.5ms, but, SD's are quite slower than SSD's which is why people want NAND support so much. NAND is not fast as transferring data but it's access write/read time is at least 10 fold faster.

TonyCubed said:
Access time of a HDD is usually ~9ms-~11ms depending on the size, rotation speed and make. SD/SSD's usually have access times below 0.5ms, but, SD's are quite slower than SSD's which is why people want NAND support so much. NAND is not fast as transferring data but it's access write/read time is at least 10 fold faster.
Click to expand...
Click to collapse
hehe, knew that but my point is that defragging only works on a HD because the head needs to go from one position to another.
Mechanical things take a much longer time so that is why we (I use a SSD so no need to) have to organise the data on the drive so it can read/write in one go.
Actually on SSD's they spread the data around since they wear out. So the controllers randomizes the data around so 1 cell isn't abused all the time.
I would love to see the benchmark of a fragged and defragged SD card.

Guys
I tried it using 2 HTC HD2 T-mobile 16gb as the senario below:
Me :
Install new build mdj v.4.1 without Formating
defrag sd card
run es file explorer
Time taken for the application to load 3 sec
My Cousin:
Install new build mdj v.4.1 without Formating
run es file explorer
Time taken for the application to load 8 sec
Do you think it's the same ?????????????????????

It seems to me that sd cards are going to wear out, probably in about the same amount of time , whether they are defragged or not. We're talking thousands of write cycles here, so 7 or 8 defrags throughout the life cycle of the card isn't going to be a huge deal. And if you wear it out a little faster, that's the price you pay for a possible performance increase. I know sd cards aren't cheap, but they're not ungodly expensive. So I would say format the card when you first get it, try and load all your crap onto it at once (as much as possible) as opposed to slowly adding files as you go, and to yes do a defrag on it at key times, say like if you're removing one Android build and installing another. The benefits of defragging may be small, or even non-existant, but the same can be said of the extra wear that defragging puts on the card.