Comments on: Determine the block size on hard disk filesystem for disk quota

By: parvesh

parvesh — Sun, 31 Jan 2010 05:27:18 +0000

hi all,
just wanted to know how no of blocks and size of disk are related just suppose i have 500gb of hard disk how blocks are numbered and how many bytes in one block

By: TodayLinux

TodayLinux — Sat, 19 Dec 2009 11:54:55 +0000

Hello Vivek / Admin,

This article is little confusing. I would suggest to make necessary correction on this article.

The output of # dumpe2fs /dev/sdb3 | grep -i ‘Block size’ is IO Block size. not the block size of filesystem which is 512K (each sector size). In your example 8 x 512K = 4096K, which is the default IO Block size.

By: Ramesh

Ramesh — Tue, 17 Nov 2009 12:05:50 +0000

I am a bit confused…

when I try to see block size with command “/sbin/dumpe2fs -h /dev/mapper/System-home”
then it says:

Block size: 4096

but when i run df command: it shows
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/System-home 61958132 49838676 8972092 85% /home

and when I run df -h, it shows

Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/System-home 60G 48G 8.6G 85% /home

does this mean that 1Kb = 4096 blocks ??

By: beanluc

beanluc — Fri, 17 Jul 2009 18:39:05 +0000

linuxrawkstar:

No, James Cape’s tip doesn’t assume that all block sizes are all the same, all the time, on all filesystems.

His tip specifically follows the example in the article, in which LINUXTITLI “discovered” a 4096b block size for the filesystem he was discussing.

LINUXTITLI, and Shane too, already showed how to discover block size for some other particular filesystem.

By: Shane Menshik

Shane Menshik — Sat, 13 Jun 2009 11:07:48 +0000

You can also get the block size for all disks using the following command, as well as readahead, size, etc.

blockdev –report

By: linuxrawkstar

linuxrawkstar — Thu, 23 Apr 2009 18:56:54 +0000

Nice tip. The comment by James Cape assumes that all block sizes are all the same, all the time, on all filesystems… hmmm. Is that true??

By: James Cape

James Cape — Sun, 08 Mar 2009 16:49:10 +0000

Umm, 409600 blocks = 409600(blocks) * 4096(B) = 1.6G

By: Teslamike

Teslamike — Wed, 28 Mar 2007 15:04:31 +0000

100MB is the same size on one system as it is on another. However, with varying block sizes, 100MB may spread over more blocks on systems with smaller block sizes than it does on a system with a larger block size.

For example, on a system with a 512B block size 100MB will take up 204800 blocks. On a system with a 64K block size 100MB will take up 1600 blocks.

By: Tortanick

Tortanick — Thu, 04 Jan 2007 11:58:03 +0000

I just found this post, it was exactly what I was looking for, thanks for the help :)

Just two things:

1) on my system I had to use double quotes rather than single quotes,

2) I think this means that 100MB could be bigger on one system than another? Am I right?

By: LinuxTitli

LinuxTitli — Mon, 29 May 2006 12:08:59 +0000

Opps :( you are right. Above command is to determine the actual size of a block on the filesystem.

Thanks, I will update post :)

By: mj

mj — Mon, 29 May 2006 11:57:11 +0000

hi,
i think that this is BLOCK SIZE OF FILESYSTEM not harddisk. Title is a bit missleading. BLOCK SIZE OF DISK is allmost always 512B