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