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On Friday 07 Aug 2015 00:23:35 wabenbau@×××××.com wrote: |
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> Mick <michaelkintzios@×××××.com> wrote: |
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> > I was wondering similar questions regarding a 32G flash card I have. |
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> > Using fdisk to partition it the starting sector was automatically |
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> > aligned with 2048 as it fdisk has been improved to deal with 4KB |
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> > sector drives. |
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> > |
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> > However, formatting it with mkfs.vfat I was none the wise if I should |
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> > use the '-s sectors-per-cluster' option or what to set it at. |
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> |
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> For the SD Cards of my Android devices I use |
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> |
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> mkfs.vfat -F32 -s64 |
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> |
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> This always gave me good performance. |
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> |
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> > Furthermore, how can I read the current cluster size off the flash |
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> > card? Is this appropriate? |
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> > |
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> > blockdev --getbsz /dev/sdb |
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> > 4096 |
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> |
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> This gives you the physical blocksize of the device. |
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> |
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> If you wanna know the cluster size, that means the blocksize of your |
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> filesystem, you can use mtools. First configure /etc/mtools/mtools.conf |
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> and set a drive letter for your SD Card, e.g. |
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> |
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> drive c: file="/dev/sde1" |
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> |
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> then use |
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> |
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> minfo C: |
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> |
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> to query a lot of information about the filesystem. Beside some other infos |
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> you will get for example: |
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> |
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> sector size: 512 bytes |
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> cluster size: 8 sectors |
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> |
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> This means cluster size is 4096 Bytes. |
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> |
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> -- |
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> Regards |
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> wabe |
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|
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Thanks! |
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|
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I've used minfo and this is what it showed: |
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|
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# minfo d: |
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device information: |
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=================== |
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filename="/dev/sdb1" |
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sectors per track: 32 |
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heads: 64 |
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cylinders: 30399 |
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|
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mformat command line: mformat -t 30399 -h 64 -s 32 -H 2048 d: |
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|
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bootsector information |
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====================== |
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banner:"mkfs.fat" |
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sector size: 512 bytes |
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cluster size: 32 sectors |
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reserved (boot) sectors: 32 |
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fats: 2 |
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max available root directory slots: 0 |
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small size: 0 sectors |
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media descriptor byte: 0xf8 |
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sectors per fat: 0 |
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sectors per track: 32 |
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heads: 64 |
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hidden sectors: 2048 |
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big size: 62257152 sectors |
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physical drive id: 0x80 |
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reserved=0x1 |
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dos4=0x29 |
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serial number: 870C0C43 |
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disk label="VERBATIM32G" |
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disk type="FAT32 " |
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Big fatlen=15193 |
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Extended flags=0x0000 |
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FS version=0x0000 |
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rootCluster=2 |
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infoSector location=1 |
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backup boot sector=6 |
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|
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Infosector: |
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signature=0x41615252 |
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free clusters=516445 |
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last allocated cluster=1448265 |
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|
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|
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So, with: |
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|
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sector size: 512 bytes |
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cluster size: 32 sectors |
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|
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I get a cluster of 16,384 bytes. This was created automagically, when I ran: |
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|
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mkfs.vfat -c -n "Verbatim Flash" /dev/sdb1 |
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|
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Without knowing the specific AU/RU as Fernando explained, should it be |
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smaller/bigger, or should I leave well alone. |
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|
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-- |
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Regards, |
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Mick |
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