OESF Portables Forum

General Forums => General Discussion => Topic started by: ShiroiKuma on July 16, 2007, 03:15:27 pm

Title: Used + Available 1k Blocks Don't Equal Total
Post by: ShiroiKuma on July 16, 2007, 03:15:27 pm

I've just noticed this. When I run df, the number of Used and Available 1k blocks doesn't equal the Total number reported for ext3 formatted CF cards. For vfat cards it matches exactly. For ext3 cards the difference exceeds 400 meg for an 8 gig card - huge difference.

I've split the card into three partitions, one ext3, one swap, and one non-mkfs-ed. Does this have any effect?

And why the difference? Is this normal?

Title: Used + Available 1k Blocks Don't Equal Total
Post by: Capn_Fish on July 16, 2007, 05:17:39 pm

Ext filesystems reserve blocks for the super user (5% by default), so that may account for the blocks. Also, there are a few other blocks that are backup blocks or something.

I may have something wrong, but I'm sure somebody will come along and elaborate/correct.

Title: Used + Available 1k Blocks Don't Equal Total
Post by: dougeeebear on July 16, 2007, 06:57:42 pm

You can use the command:
mke2fs -m 0 /dev/hda1
to format a CF card to ext2 without creating the reserve blocks.

Maybe something like:
mke3fs -m 0 /dev/hda1
would work that way for ext3, I don't know.

Title: Used + Available 1k Blocks Don't Equal Total
Post by: the_oak on July 17, 2007, 10:38:40 pm

I have always heard that ext3 file system is hard on CF cards due to journaling putting excess writes to disk. Maybe whoever posted this info before can elaborate on newest opinion concerning use of ext3?

Title: Used + Available 1k Blocks Don't Equal Total
Post by: Capn_Fish on July 18, 2007, 05:18:14 pm

I heard the same thing, that using EXT2 on flash is better for it, eg causes less wear.