ext3/4 file size limit

joemon83 · 11-13-2019, 12:14 AM

Hi,
how is the max filesize limit determined in a ext 3/4 partition.
As per wiki, https://en.wikipedia.org/wiki/Ext3#Size_limits
I understand the relationship between filesystem size and the block size. But not really getting the relationsip between block size and the max size limit of an individual file.

berndbausch · 11-13-2019, 01:30 AM

The larger a block, the more pointers to indirect blocks fit in a block. With the diagram at https://en.m.wikipedia.org/wiki/Ext2#Inodes, you should be able to do the math.

joemon83 · 11-13-2019, 11:29 PM

Thanks for the reply. But even if the block is not large enough, it can still contain multiple levels to indirect pointers to hold any size of file rite ? It can have indirect, double indirect, triple indirect, so on.....

joemon83 · 11-13-2019, 11:35 PM

Ok, I think there is restriction on the no. of indirect block pointers (1..128) in each level.
So if the block size if large, can the inode hold more block pointers than just 3 as show in the diagram ?

berndbausch · 11-14-2019, 12:40 AM

Quote:

Originally Posted by joemon83

Ok, I think there is restriction on the no. of indirect block pointers (1..128) in each level.
So if the block size if large, can the inode hold more block pointers than just 3 as show in the diagram ?

The inode size is not configurable, as far as I know. An inode always has the same number of block pointers, 10 direct, 3 indirect according to the diagram.

There are direct blocks, indirect blocks, double indirect blocks and triple indirect blocks. That's it. No quadruple and so on.

joemon83 · 11-15-2019, 10:36 PM

Ok, so I think the summary is..the no. of indirect pointers are fixed.
The larger the block size, the bigger the file size it can support.