How many bytes per inodes?

Question

I need to create a very high number of files which are not very large (like 4kb,8kb). It's not possible on my computer cause it takes all inodes up to 100% and I cannot create more files :

$ df -i /dev/sda5 Filesystem            Inodes   IUsed   IFree IUse% Mounted on /dev/sda5            54362112 36381206 17980906   67% /scratch 

(I started deleting files, it's why it's now 67%)

The bytes-per-nodes are of 256 on my filesystem (ext4)

$ sudo tune2fs -l /dev/sda5 | grep Inode Inode count:              54362112 Inodes per group:         8192 Inode blocks per group:   512 Inode size:               256 

I wonder if it's possible to set this value very low even below 128(during reformating). If yes,what value should I use? Thx

Answer 1

The default bytes per inode is usually 16384, which is the default inode_ratio in /etc/mke2fs.conf (it's read prior to filesystem creation). If you're running out of inodes, you might try for example:

mkfs.ext4 -i 8192 /dev/mapper/main-var2 

Another option that affects this is -T, typically -T news which further reduces it to 4096.

Also, you can not change the number of inodes in a ext3 or ext4 filesystem without re-creating or hex-editing it. Reiser filesystems are dynamic so you'll never have an issue with them.

Answer 2

You can find out the approximate inode ratio by dividing the size of available space by the number of available inodes. For example:

$ sudo tune2fs -l /dev/sda1 | awk -F: ' \     /^Block count:/ { blocks = $2 } \     /^Inode count:/ { inodes = $2 } \     /^Block size:/ { block_size = $2 } \     END { blocks_per_inode = blocks/inodes; \           print "blocks per inode:\t", blocks_per_inode, \                 "\nbytes per inode:\t", blocks_per_inode * block_size }'  blocks per inode:    3.99759  bytes per inode:     16374.1