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Mick <michaelkintzios@×××××.com> wrote: |
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|
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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 |
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> > > have. Using fdisk to partition it the starting sector was |
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> > > automatically aligned with 2048 as it fdisk has been improved to |
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> > > deal with 4KB sector drives. |
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> > > |
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> > > However, formatting it with mkfs.vfat I was none the wise if I |
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> > > should use the '-s sectors-per-cluster' option or what to set it |
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> > > 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 |
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> > configure /etc/mtools/mtools.conf and set a drive letter for your |
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> > 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 |
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> > other infos 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, |
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> 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 |
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> be smaller/bigger, or should I leave well alone. |
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|
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I think, this depends on how big the files are that you wanna store on the |
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card. If you plan to store many very small files on it, than it is probably |
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better to choose a smaller cluster size. But for music files, pictures and |
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videos this size should be ok. |
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|
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-- |
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Regards |
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wabe |
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