A nasty ataraid experience.

[Michel Talon]

Bruce M Simpson wrote:

> Following the rebuild procedure in the Handbook, if you try to run 
> "atacontrol rebuild" from the FreeBSD 7.1 LiveFS, it'll break. I ran it 
> thinking that it had some kind of magic in it which I couldn't achieve 
> using dd alone, which is partly true, but also partly not true.
> 
> It has a hardcoded path to /usr/bin/nice, which it runs using the 
> system() libc call, and unfortunately, the LiveFS is rooted at /mnt2. It 
> does this after it issues an ioctl() to tell the ATA driver to copy and 
> rewrite the meta-data to the new "spare" drive.

I always use the LiveFS cdromin the following way:

chroot /mnt2
set -o emacs
mount -t devfs devfs /dev
export PAGER=more

so that i am exactly in the same situation as on a real machine.

> HOMEWORK: Why does fdisk still assume 16 heads... ? Perhaps we should 
> have a switch to tell it to use the LBA-style C/H/S converted geometry?

FreeBSD fdisk is a calamity.


> I also now understand that I can't rely on RAID alone to keep the 
> integrity of my own data -- there is no substitute for backups, I just 
> wish there were realistic backup solutions for individuals trying to do 
> things with technology right now, without paying over the odds, or being 
> ripped off.


A solution to keep backups without "paying over the odds" is to backup
your data to another hard disk. This doesn't mean using RAID mirror, it
means using rsync or similar to copy data regularly. It is preferable
that this occurs on another machine, and even better in another
geographic location. But even if the backup disk is on the same machine,
this protects againts inadvertent deletions of a file or RAID
misbehaviors. The risk being that some hardware problem simultaneously
corrupts the main storage and the backup. Modern features such as
UFS snapshots or better ZFS snapshots allow to produce better backups.


-- 

Michel TALON