FreeBSD 5.3 - Raid

[Robert Slade]

On Sun, 2005-02-27 at 15:26, Ean Kingston wrote:
> 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).

What confused me is that it did not seem to cover GEOM which came up
during my searches.

> 
> 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 am using 5.3.

> 
> > 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,

Many many thanks for your explanation. I do take your points regarding
understanding how the raid works before providing it for users. I have a
little time before the box has to go live and I will use it check the
system. 

Rob