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ext4

Ext4 FS: max file size

If I am not wrong, than with triple indirect addressing, the maximum file size for ext3 would be (4G+4M+4K).

Likewise, what will be the the maximum file size for an ext4 FS using extents if we assume a 4KB disk block size?

Solution

  • BS = Block size = 4 KiB

    You missed the 12 direct pointers in your calculation for ext3:

    (12*BS = 48 KiB) + 4 MiB + 4 GiB + 4 TiB

    For ext4, we use 32-bit indexing for the extents:

    2^32 * (BS = 2^12) = 2^44 = 16 TiB

    which is the number you would e.g. also find on Wikipedia for the maximum ext4 file size.