[Gllug] What are the best practices for Linux partitioning & Mount points for Production systems

Alain Williams addw at phcomp.co.uk
Fri Mar 2 15:31:06 UTC 2012

On Fri, Mar 02, 2012 at 12:44:35PM +0000, Phil Hands wrote:

> My normal setup is /boot and / on non-LV partitions (normally on
> software RAID1 across every physical disk in the machine, and ensuring
> that every disk also has grub installed, and working, on it).  That way
> you can get somewhere towards a bootable system if any single disk
> survives the disaster -- being software RAID1, in extremis you can get
> it to boot with root=/dev/sda2 (say) and it'll even survive you messing
> up the raid modules for the kernel.
> ....

An interesting problem that happened to one machine that I look after recently.
The machine had had intermittent disk hardware problems (low level motherboard,
sata disk configuration issues). A new disk was purchased and it ended up with a
3 way mirror (RAID 1 - Linux kernel MD).

Later the machine would slow up for 30-60 seconds maybe once or twice a day,
eventually I traced it to sda appearing to take that time to service requests. I
tested this by removing sda from the mirror set ... no problems after a few days
and so thought 'problem solved'.

The disk was not removed from the machine.

A couple of months later I requested that the user reboot the new machine since
a new kernel had been installed .... they did but it ran the old kernel ????

Long story short: the BIOS booted from the first disk that it saw: sda. That was
no longer being updated because it was not in the mirror any more ... so
grub.conf on that disk was not updated.

Moral: remove unused hardware.

Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256  http://www.phcomp.co.uk/
Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php
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