FreeBSD 5.3 - Raid

[Ean Kingston]

On February 27, 2005 08:59 am, Robert Slade wrote:
> Hi,
>
> Sorry if this is dumb question.
>
> I have a new install of FreeBSD on a single IDE drive. I have backed this
> up so I am not too concerned about drive failure. I have now added 2, 250
> Gbyte drives (ad3 and ad4) to hold data. I would like to mirror them using
> sofware raid and mount them as /home to hold the users data which is
> critical.
>
> I have read the manual and searched the web for a simple way to do the
> above. The manual seems to cover complex solutions and may be somewhat
> behind the times.

The handbook is pretty up to date (I just looked at it).

I would suggest you ignore  the section that describes 'ccd'. It is easier to 
set up than vinum but I have found the current implementation of ccd to be 
unreliable.

If you are using FreeBSD 5.x (hopefully 5.3), use gvinum instead of vinum. It 
works the same way (commands and options) as vinum but (from what I 
understand) it has some improvements.

> I guess what I am looking for is a howto couched in such a way that even a
> windows user can understand :-).

I assume you have physically installed your two disks (ad3, ad4).

If you have not done so yet, use fdisk(8) to create a single slice (what 
Windows calls a partition). This can also be done through sysinstall

Also, if you have not done so yet, use bsdlabel(8) to create a FreeBSD 
partition (no Windows equivalent). Be sure to set the 'fstype' to 'vinum'.

At this stage I will assume that you have set up your two disks so that you 
have ad3s1a and ad4s1a as the slices you wish to use for vinum. I think you 
can do this with sysinstall as well.

NOTE: you do not need to use newfs to create the filesystem, that would happen 
after you have setup your RAID volumes.

Create a file, we will call it gvinum.conf and put the following into it:

# Define the FreeBSD Partitions to be used for Vinum
drive a device /dev/ad3s1a
drive b device /dev/ad4s1a
#
# Define each volume/plex/subdisk
volume home				# home volume
 plex org concat			# concatinated plex (1st half of mirror)
  sd length 8192m drive a	# 1st subdisk of concatinated plex
 plex org concat			# concatinated plex (2nd half of mirror)
  sd length 8192m drive b	# 1st subdisk of 2nd concatinated plex

Now, use the vinum(8) 'create' command to set things up using the 
configuration file.

You should now have a /dev/gvinum/home device. You can newfs it, mount it, and 
add it to your /etc/fstab.

newfs /dev/gvinum/home

mount /dev/gvinum/home /home

> Any suggestions please.

Do read and try to understand chapter 17 of the FreeBSD handbook if you want 
to get into software RAID.

Rob, you really need to understand how software RAID works if you want to take 
advantage of it. When you have a disk failure, you need to know what to do to 
recover your data. In order to do that you really need to understand how the 
software RAID works.

You may want to consider setting up a seconds FreeBSD partition on each of 
your two new disks so that you can fiddle with RAID and figure out how to 
recover from a disk failure.

-- 
Ean Kingston

E-Mail: ean AT hedron DOT org
URL: http://www.hedron.org/