Change the block size of file system from 4K to 8K

[Amged Ahmed Kushlaf]

Dear RedHat experts,



The default block size of redhat operating system ( /) is 4K, so how can I
change the block size of the root directory ("/") to 8K during the
installation.

If not possible during the installation, so Is there any other ways to make
it 8K.



Your help is highly appreciated



Thanks,



Amged

[George Magklaras]

I assume that you are setting this up with ext3 and hence my answer ties
to this. If your filesystem is different, you should say so.

Note: *In ext3, an 8K block size on the fs is only possible if you use
Itanium and other 8K architectures. If your architecture is x86, x86_64,
it is not possible to have a block size greater than 4k*. If you try to
make an ext3 fs you will fail with an error message similar to this:

mkfs.ext3: 8192-byte blocks too big for system (max 4096)

So,if your server architecture can take it, you can
i)use parted post installation to make the partition and then type the
following example (if your partition is called for instance /dev/sda2):

mkfs -t ext3 -b 8192 /dev/sda2

ii)There is also kickstart
(http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Installation_Guide/ch-kickstart2.html).
From a quick browsing on the RedHat manual, I cannot find the exact
switch to specify block size (must be set with size)

#part / --fstype ext3 --size=1024...etc

So, I would recommend number i) as a faster option.
--
--
George Magklaras BSc Hons MPhil
RHCE:805008309135525

Senior Computer Systems Engineer/UNIX-Linux Systems Administrator
EMBnet Technical Management Board
The Biotechnology Centre of Oslo,
University of Oslo
http://folk.uio.no/georgios

Post by Amged Ahmed Kushlaf
Dear RedHat experts,
The default block size of redhat operating system ( /) is 4K, so how can I
change the block size of the root directory ("/") to 8K during the
installation.
If not possible during the installation, so Is there any other ways to make
it 8K.
Your help is highly appreciated
Thanks,
Amged

[George Magklaras]

This implies that you cannot safely or reliably change it but you have
to re-format the fs.., OK?

GM

Post by George Magklaras
I assume that you are setting this up with ext3 and hence my answer ties
to this. If your filesystem is different, you should say so.
Note: *In ext3, an 8K block size on the fs is only possible if you use
Itanium and other 8K architectures. If your architecture is x86, x86_64,
it is not possible to have a block size greater than 4k*. If you try to
mkfs.ext3: 8192-byte blocks too big for system (max 4096)
So,if your server architecture can take it, you can
i)use parted post installation to make the partition and then type the
mkfs -t ext3 -b 8192 /dev/sda2
ii)There is also kickstart
(http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Installation_Guide/ch-kickstart2.html).
From a quick browsing on the RedHat manual, I cannot find the exact
switch to specify block size (must be set with size)
#part / --fstype ext3 --size=1024...etc
So, I would recommend number i) as a faster option.