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2007-04-11
, 22:37
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Posts: 3,401 |
Thanked: 1,255 times |
Joined on Nov 2005
@ London, UK
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#22
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300MB in 10-15 minutes doesn't sound right - something is wrong with the card, the card reader or the PC! 
It's quite hard to benchmark the write speed on the N800 because of the internal OS filesystem buffering.
Using the following (utterly bogus) test...
...will "write" 128MB of data to a Transcend Class 2 8GB card (high speed, 4-bits wide) in 20.64 seconds (latest 3.2007.10-7 SDHC kernel) which works out at just over 6.2MB/s write speed.
I know the results from this test are incorrect, but it does go to show that you won't really see a great deal of difference between Class 2 and Class 4 write performance in day-to-day usage. The OS will finish writing the data asynchronously to the Class 4 card faster than it will the Class 2 card, but you're not likely to notice.
You should see a difference between Class 2 and Class 4 in a Windows PC as file transfers should be quicker with the Class 4 card, in which case your buying decision should be based on how often you intend to bulk copy data to the card when it is connected to a PC.
IMHO, the N800 isn't likely to see any benefit when using a Class 4 or faster card - Class 2 will be fine.
It's quite hard to benchmark the write speed on the N800 because of the internal OS filesystem buffering.
Using the following (utterly bogus) test...
Code:
/home/user # sync; time sh -c "dd if=/dev/zero of=/dev/mmcblk1 bs=1M count=128; sync; sync; sync;" 128+0 records in 128+0 records out real 0m 20.64s user 0m 0.00s sys 0m 1.39s
I know the results from this test are incorrect, but it does go to show that you won't really see a great deal of difference between Class 2 and Class 4 write performance in day-to-day usage. The OS will finish writing the data asynchronously to the Class 4 card faster than it will the Class 2 card, but you're not likely to notice.
You should see a difference between Class 2 and Class 4 in a Windows PC as file transfers should be quicker with the Class 4 card, in which case your buying decision should be based on how often you intend to bulk copy data to the card when it is connected to a PC.
IMHO, the N800 isn't likely to see any benefit when using a Class 4 or faster card - Class 2 will be fine.
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2007-04-12
, 00:21
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Posts: 1,310 |
Thanked: 820 times |
Joined on Mar 2006
@ Irving, TX
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#23
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Well... did redo the speed test using 319MB size AVI file copied from computer to N800. It took 740 seconds... (that is over 12 minutes...). By reading back the same file to PC took only 30 seconds! Thus the read speed is over 10MB/sec, which is over 20x faster than write speed! That is with "regular" 4GB SD card, not SDHC card. (I do have the SDHC kernel installed which seem to be faster than the stock kernel, even with non-SDHC cards.)
At any rate even Class 2 card would be many times faster to write than my current 4GB card. (Read speed might be slightly slower?)
Based on your recommendation I'll propably just get a Class 2 card.
At any rate even Class 2 card would be many times faster to write than my current 4GB card. (Read speed might be slightly slower?)
Based on your recommendation I'll propably just get a Class 2 card.
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2007-04-25
, 23:26
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Posts: 273 |
Thanked: 104 times |
Joined on Mar 2007
@ Manitoba, Canada
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#24
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This seems like the best thread to post my questions, so here goes:
1) I have a brand-new N800 (yay!) and I purchased two 8gb Patriot SDHC cards for it. I would assume that before I can use them that I need to format/partition them (?), but does this mean I need to go out and purchase a USB multi-card-reader with SDHC support before I can do this? The card readers on my Linux PCs don't seem to recognize these cards (nio big surprise). How do the rest of you SDHC people do this? Can I be sure that any card reader that I purchase will work on my Linux systems (I am assuming that any desire to create EXT2/3 partitions without using them under Linux would be impossible).
2) I need to have clear(er) guidance on the best way to partition these cards. I have read that they *must* have a FAT(32?) partition on them -- is this true? How large? Being a Linux guy I would simply prefer to format them completely as EXT3.
Please help guide me!
1) I have a brand-new N800 (yay!) and I purchased two 8gb Patriot SDHC cards for it. I would assume that before I can use them that I need to format/partition them (?), but does this mean I need to go out and purchase a USB multi-card-reader with SDHC support before I can do this? The card readers on my Linux PCs don't seem to recognize these cards (nio big surprise). How do the rest of you SDHC people do this? Can I be sure that any card reader that I purchase will work on my Linux systems (I am assuming that any desire to create EXT2/3 partitions without using them under Linux would be impossible).
2) I need to have clear(er) guidance on the best way to partition these cards. I have read that they *must* have a FAT(32?) partition on them -- is this true? How large? Being a Linux guy I would simply prefer to format them completely as EXT3.
Please help guide me!
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2007-04-25
, 23:46
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Posts: 449 |
Thanked: 18 times |
Joined on Apr 2006
@ Eureka, CA
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#25
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See the SDHC wiki:
http://www.internettablettalk.com/wi..._to_a_computer
In short - you don't need to format. You just need to patch the kernel to get SDHC support. This is not hard to do.
Good luck.
http://www.internettablettalk.com/wi..._to_a_computer
In short - you don't need to format. You just need to patch the kernel to get SDHC support. This is not hard to do.
Good luck.
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2007-04-26
, 07:39
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Posts: 2,152 |
Thanked: 1,490 times |
Joined on Jan 2006
@ Czech Republic
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#26
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Originally Posted by darethehair
N800 works as usb card reader. once you flash sdhc kernel you can reformat and repartition cards from PC over USB.
I would assume that before I can use them that I need to format/partition them (?), but does this mean I need to go out and purchase a USB multi-card-reader with SDHC support before I can do this? The card readers on my Linux PCs don't seem to recognize these cards (nio big surprise). How do the rest of you SDHC people do this?
Originally Posted by darethehair
Default system simply expects first partition to be FAT. With fist partition being FAT(32) you won't need any modification of system files. It is possible to have ext2 but it may be less practical when accessing card over USB from non-linux PC and you also need to hack few configuration files (/etc/fstab at least).
2) I need to have clear(er) guidance on the best way to partition these cards. I have read that they *must* have a FAT(32?) partition on them -- is this true? How large? Being a Linux guy I would simply prefer to format them completely as EXT3.
In my opinion the easiest is to keep first one as FAT for data that I wish to share over USB and create other partition(s) as ext2 or ext3 for things that need permissions. If you are advanced linux user you may also consider transferring system from flash to mmc card to have more space, faster system (depends on card speed) and easier crash recovery
http://maemo.org/maemowiki/HowTo_EAS..._From_MMC_card
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2007-05-04
, 19:28
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Posts: 2 |
Thanked: 0 times |
Joined on May 2007
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#27
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Originally Posted by johsua
I just can't get that guide to work.
See the SDHC wiki:
http://www.internettablettalk.com/wi..._to_a_computer
In short - you don't need to format. You just need to patch the kernel to get SDHC support. This is not hard to do.
Good luck.
I just don't understand why I get that "error".
http://kirkedam.mine.nu/kwk/N800%20Stuff/Bilde340.jpg
Thanks in advance
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2007-05-04
, 20:32
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Posts: 2,152 |
Thanked: 1,490 times |
Joined on Jan 2006
@ Czech Republic
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#28
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Originally Posted by Karl-Wilhelm
You did not enter correct path to kernel flasher archive. I have added more details to that wiki page. Read again and use proper path, it depends on where you saved those files.
I just can't get that guide to work.
I just don't understand why I get that "error".
http://kirkedam.mine.nu/kwk/N800%20Stuff/Bilde340.jpg
Thanks in advance
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2007-05-04
, 21:23
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Posts: 2 |
Thanked: 0 times |
Joined on May 2007
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#29
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Originally Posted by fanoush
Thanks =) I got it to work now! I had done a couple of things wrong...
You did not enter correct path to kernel flasher archive. I have added more details to that wiki page. Read again and use proper path, it depends on where you saved those files.
Happy weekend
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2007-05-06
, 22:31
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Posts: 57 |
Thanked: 4 times |
Joined on May 2007
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#30
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Originally Posted by Mara
any new result with the class 2 card?i am planning to buy a non-standard 4gb sd to use with my n800, if it is as what you tested, i would choose sdhc card. thanks.
Well... did redo the speed test using 319MB size AVI file copied from computer to N800. It took 740 seconds... (that is over 12 minutes...). By reading back the same file to PC took only 30 seconds! Thus the read speed is over 10MB/sec, which is over 20x faster than write speed! That is with "regular" 4GB SD card, not SDHC card. (I do have the SDHC kernel installed which seem to be faster than the stock kernel, even with non-SDHC cards.)
At any rate even Class 2 card would be many times faster to write than my current 4GB card. (Read speed might be slightly slower?)
Based on your recommendation I'll propably just get a Class 2 card.
--
posted from zaurus
| The Following User Says Thank You to chyang For This Useful Post: | ||
I have seen some speed test numbers here about speeds of different cards, but I do not remember seeing anything about write speed of different SDHC class cards? Would the Class 4 be faster than Class 2 to write to, when using the patched SDHC kernel in N800?