we have BBB based custom board with 256MB RAM and 4GB eMMC,
I have partitioned it using below code,
parted --script -a optimal /dev/mmcblk0 \
mklabel gpt \
mkpart primary 128KiB 255KiB \
mkpart primary 256KiB 383KiB \
mkpart primary 384KiB 511KiB \
mkpart primary 1MiB 2MiB \
mkpart primary 2MiB 3MiB \
mkpart primary 3MiB 4MiB \
mkpart primary 4MiB 5MiB \
mkpart primary 5MiB 10MiB \
mkpart primary 10MiB 15MiB \
mkpart primary 15MiB 20MiB \
mkpart primary 20MiB 21MiB \
mkpart primary 21MiB 22MiB \
mkpart primary 22MiB 23MiB \
mkpart primary 23MiB 28MiB \
mkpart primary ext4 28MiB 528MiB \
mkpart primary ext4 528MiB 1028MiB \
mkpart primary ext4 1028MiB 1128MiB \
mkpart primary ext4 1128MiB 1188MiB \
mkpart primary ext4 1188MiB 2212MiB \
mkpart primary ext4 2212MiB 2603MiB \
mkpart primary ext4 2603MiB 2639MiB \
mkpart primary ext4 2639MiB 100% \
And then formatted file system partitions using below command
mkfs.ext4 -j -L $LABEL $PARTITION
Now when I read file system block size using tune2fs, I see different value for partitions less than 1GiB and partition greater or equal to 1GiB partition.
# tune2fs -l /dev/mmcblk0p15 | grep Block
Block count: 512000
Block size: 1024
Blocks per group: 8192
#
#
# tune2fs -l /dev/mmcblk0p16 | grep Block
Block count: 512000
Block size: 1024
Blocks per group: 8192
#
#
# tune2fs -l /dev/mmcblk0p19 | grep Block
Block count: 262144
Block size: 4096
Blocks per group: 32768
# tune2fs -l /dev/mmcblk0p22 | grep Block
Block count: 1191936
Block size: 4096
Blocks per group: 32768
I am not able to understand why block sizes are different. moreover mke2fs.conf is having all default values only and blocksize mentioned there is 4096.
[defaults]
base_features = sparse_super,filetype,resize_inode,dir_index,ext_attr
default_mntopts = acl,user_xattr
enable_periodic_fsck = 0
blocksize = 4096
inode_size = 256
inode_ratio = 16384
[fs_types]
ext3 = {
features = has_journal
}
ext4 = {
features = has_journal,extent,huge_file,flex_bg,uninit_bg,dir_nlink,extra_isize
auto_64-bit_support = 1
inode_size = 256
}
ext4dev = {
features = has_journal,extent,huge_file,flex_bg,uninit_bg,dir_nlink,extra_isize
inode_size = 256
options = test_fs=1
}
small = {
blocksize = 1024
inode_size = 128
inode_ratio = 4096
}
floppy = {
blocksize = 1024
inode_size = 128
inode_ratio = 8192
}
big = {
inode_ratio = 32768
}
huge = {
inode_ratio = 65536
}
news = {
inode_ratio = 4096
}
largefile = {
inode_ratio = 1048576
blocksize = -1
}
largefile4 = {
inode_ratio = 4194304
blocksize = -1
}
hurd = {
blocksize = 4096
inode_size = 128
}
Can someone explain/suggest a doc/hint why block sizes are different for different partitions?
mke2fs.conf
! let me check thatmke2fs
utlity man page. I will update answer so that someone facing similar issue can look at it.