Block Device Examples
Windows 10
NTFS refers to logical blocks as clusters.
On this NTFS volume, each cluster is 4 KiB.
PS C:\Windows\system32> fsutil fsinfo ntfsinfo C:
NTFS Volume Serial Number : 0x2abe26bebe268285
NTFS Version : 3.1
LFS Version : 2.0
Total Sectors : 1,759,307,063 (838.9 GB)
Total Clusters : 219,913,382 (838.9 GB)
Free Clusters : 75,517,627 (288.1 GB)
Total Reserved Clusters : 9,087 ( 35.5 MB)
Reserved For Storage Reserve : 0 ( 0.0 KB)
Bytes Per Sector : 512
Bytes Per Physical Sector : 4096
Bytes Per Cluster : 4096
Bytes Per FileRecord Segment : 1024
Clusters Per FileRecord Segment : 0
Mft Valid Data Length : 2.11 GB
Mft Start Lcn : 0x00000000000c0000
Mft2 Start Lcn : 0x0000000000000002
Mft Zone Start : 0x00000000089d4080
Mft Zone End : 0x00000000089e08a0
MFT Zone Size : 200.13 MB
Max Device Trim Extent Count : 256
Max Device Trim Byte Count : 0xffffffff
Max Volume Trim Extent Count : 62
Max Volume Trim Byte Count : 0x40000000
Resource Manager Identifier : 1D7A365A-EDCE-11EF-AD26-38FC98203B3A
Debian Trixie
Linux has lots of potential filesystems and filesystems can have different block sizes.
Finding the disk.
root@tesseract:/home/ariadne# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
loop0 7:0 0 1.1M 1 loop /snap/avahi/814
loop1 7:1 0 1.1M 1 loop /snap/avahi/587
loop2 7:2 0 55.5M 1 loop /snap/core18/2979
loop3 7:3 0 55.5M 1 loop /snap/core18/2999
loop4 7:4 0 66.8M 1 loop /snap/core24/1587
loop5 7:5 0 66.8M 1 loop /snap/core24/1643
loop6 7:6 0 174.4M 1 loop /snap/postman/360
loop7 7:7 0 174.5M 1 loop /snap/postman/362
loop9 7:9 0 50.1M 1 loop /snap/snapd/27406
loop10 7:10 0 50.1M 1 loop /snap/snapd/27591
sda 8:0 0 32G 0 disk
├─sda1 8:1 0 31G 0 part /
├─sda2 8:2 0 1K 0 part
└─sda5 8:5 0 975M 0 part [SWAP]
Querying the disk directly for its logical sector size.
root@tesseract:/home/ariadne# blockdev --getss /dev/sda
512
Querying the filesystem.
This ext4 filesystem uses 4096-byte filesystem blocks.
root@tesseract:/home/ariadne# tune2fs -l /dev/sda1
tune2fs 1.47.0 (5-Feb-2023)
Filesystem volume name: <none>
Last mounted on: /
Filesystem UUID: 5a82dda3-b341-4602-9523-cd51db6981ee
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg sparse_super large_file huge_file dir_nlink extra_isize metadata_csum
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 2035824
Block count: 8138240
Reserved block count: 406912
Overhead clusters: 172853
Free blocks: 1083226
Free inodes: 1378863
First block: 0
Block size: 4096
Fragment size: 4096
Group descriptor size: 64
Reserved GDT blocks: 1024
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8176
Inode blocks per group: 511
Flex block group size: 16
Filesystem created: Tue Jul 18 19:42:50 2023
Last mount time: Fri Jul 24 14:14:51 2026
Last write time: Tue Jul 28 17:00:06 2026
Mount count: 116
Maximum mount count: -1
Last checked: Tue Jul 18 19:42:50 2023
Check interval: 0 (<none>)
Lifetime writes: 744 GB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 32
Desired extra isize: 32
Journal inode: 8
Default directory hash: half_md4
Directory Hash Seed: 65bf92d6-f469-47de-a71d-e4f821da4415
Journal backup: inode blocks
Checksum type: crc32c
Checksum: 0xff19412a