# what blocksize does my harddisk have? cat /sys/block/md0/queue/physical_block_size; 512 # alternatively stat -f /dev/md0; File: "/dev/md0" ID: 3d822af00fc67f8d Namelen: 255 Type: ext2/ext3 <- it should be actually EXT4! Block size: 1024 Blocks: Total: 142799 Free: 16739 Available: 16739 Inodes: Total: 36864 Free: 30454
fdisk -l /dev/md0 | grep Units
Units = cylinders of 8 * 512 = 4096 bytes
fdisk -l /dev/sda3 | grep Units
Units = cylinders of 16065 * 512 = 8225280 bytes
Note the fdisk output says “cylinders of 16065 * 512”. This means that there are 512 bytes per block on the disk.
every file system needs to split up a partition into blocks to store files and file parts.
This is why there is a different block size for a file system as you can see here:
stat -f .
File: "."
ID: 236d62321492c2ce Namelen: 255 Type: ext2/ext3
Block size: 4096 Fundamental block size: 4096
Blocks: Total: 76899893 Free: 8380419 Available: 4474114
Inodes: Total: 39075840 Free: 38013010
can also be read with:
tune2fs -l /dev/sda1
tune2fs 1.42.12 (29-Aug-2014)
Filesystem volume name:
Last mounted on: /
Filesystem UUID: e9ca2a70-bbb4-4b00-aa8f-14ccdb1c7c3d
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 8192000
Block count: 32768000
Reserved block count: 1638400
Free blocks: 31353633
Free inodes: 8051456
First block: 0
Block size: 4096 <----- HERE IT IS
Fragment size: 4096
Reserved GDT blocks: 1016
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8192
Inode blocks per group: 512
Flex block group size: 16
Filesystem created: Mon Apr 24 12:22:32 2017
Last mount time: Fri May 19 10:03:13 2017
Last write time: Fri May 19 10:03:55 2017
Mount count: 13
Maximum mount count: -1
Last checked: Fri May 12 10:11:37 2017
Check interval: 0 ()
Lifetime writes: 31 GB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Journal inode: 8
First orphan inode: 524303
Default directory hash: half_md4
Directory Hash Seed: cbc60d19-3f00-4607-9017-5098cb4b96f5
Journal backup: inode blocks
source & creditz: http://wiki.linuxquestions.org/wiki/Block_devices_and_block_sizes
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