Re: [gentoo-user] Ext4 status - Alternative to ext2/3 for gentoo portage and more

[Florian Philipp]

On Fri, 2008-02-15 at 21:05 +0100, Wael Nasreddine wrote:
> Currently I have 2 partitions, a root and home partition, fortunately
> on LVM array, I was thinking of splitting them to "/, /usr, /var, /home,
> /usr/portage, /mnt/storage" the latter is to be used for Mp3z (around
> 12000) and movies...
>
> I was thinking of having the below filesystem schema:
> /               : ext3 (-j -O dir_index,sparse_super,filetype) (Good mkfs options ??)
> /usr            : xfs (I never used it so please suggest mkfs.xfs options)
> /var            : //
> /home           : ext3 (-m 0 -j -O dir_index,sparse_super,filetype) (Good mkfs options ??)
> /usr/portage    : ReiserFS (3? 4? options??)
> /mnt/storage    : ext3 (-m 0 -j -O dir_index,sparse_super,filetype) (Good mkfs options ??)
>
>
> Could you please comment/complete/change the schema above ?? I really
> would like to speed up my system a little bit, My system is entirely
> built on LVM array, and LVM is on DM-CRYPT so as you can see it's a
> quite slow due to the encryption...
>
> Oh one last thing, What do you suggest for a server? I have a Gentoo
> server and uptime can be over 5/6 months, everytime I reboot the
> server I have to manually scan the filesystem due to errors
> everywhere, any suggestions??
>
> Thanks...

First of all, if there are filesystem errors, check your cables, your
controller and your disks. I don't think filesystem errors count as
normal behavior ...

To your filesystem scheme: Why do you use xfs for usr? AFAIK XFS is good
at write speed but not worth the trouble when reading data and data in
usr is usually written once, updated every few months and read many
times a week (on rebooting Desktop PCs maybe once a day). I'd use
reiserfs3.6, maybe even without notail to make it more space efficient.

I'd also use ext2 on /usr/portage. These data don't need journaling.
Everything's got an MD5-sum to make sure it's unchanged after a crash
and you can easily resync. I found ext2 with 2k blocks to be faster than
reiserfs3.6, even on read-performance.

If I were you, I'd also use separate volumes for /tmp and /var/tmp
(without ccache) with xfs.

/home could use data=journal. Those data are precious and if I remember
correctly, this setting even brings an obscure (i.e. undocumented) speed
improvement with many parallel disk accesses, for example in a
multi-user environment.