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Re: /usr/lib vs /usr/libexec



Russell Coker <russell@coker.com.au> writes:

> On Tuesday 10 May 2005 10:36, Goswin von Brederlow 
> <brederlo@informatik.uni-tuebingen.de> wrote:
>> - / can't be on lvm, raid0, raid5, reiserfs, xfs without causing
>> problems for /boot.
>
> I believe that there are LILO patches for /boot on LVM.  There's no reason why 
> GRUB and other boot loaders couldn't be updated in the same manner.  The most 
>...

They don't now and there are way more bootloaders than just grub and
lilo.

> But generally the best solution to such problems is to have a separate 
> partition for /boot.  Red Hat defaults to an LVM install (including LVM root) 
> with a regular 100M partition for /boot, that works well.

No lvm backup data available in case of superblock corruption. Bad
idea. No booting with init=/bin/sh to patch things back together as /
can't be mounted. Bad idea again.

/ on lvm is a major pain in case of error and if you already need a
seperate / partition adding another for /boot is a bit stupid.

The best solution is a regular 100-200Mb partition for / including
/boot imho.

>> - a larger FS has more chance of failing so you risk having a fully
>> broken system more often
>
> I doubt that.
>
> I think that a FS that is written less has less chance of failing, which is an 
> extra reason for having /var and /home on different file systems to /.  If 
> you have /var and /home on separate partitions then / should not get many 
> writes and should have little chance of corruption regardless of size.
>
>> - /usr can be easily network (shared accross the same arch) mounted
>> while / (due to /etc) can't
>
> Why is this desirable in the days of large disks?  There is no machine for 
> which I am responsible which has a disk space issue other than my laptop.  
> None of my machines has /usr taking any significant portion of the disk 
> space.

I have two recently bought systems without disk. Just a small flash to
boot from. Those mips based wireless and dsl routers from linksys and
similar are very popular as well as meshcubes.

>> - / needs functioning device nodes on it while usr can be mounted nodev
>
> The current Fedora setup of having an initrd create device nodes on a tmpfs is 
> working quite well and could be copied for Debian.
>
>> - a small / can be replicated across many disks to ensure the system
>> always comes up and e.g. at least send an email to the admin. / can
>> even be an initrd
>
> How big can an initrd be?  The default is 4M which isn't going to do well 
> for /.

The limit is either 1GB or slightly below 2GB for 32bit (+amd64)
systems. Less for mips I guess due to the hardwired address space.

Enough ram provided of course (4GB ram for a 2GB ramdisk as it gets
copied around by the kernel).

The problem is more how much ram do you want to spend on it than how
much linux can use.

MfG
        Goswin



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