FreeBSD 5.3 - Raid

[Robert Slade]

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.

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

Any suggestions please.

Rob

[Peter Schuller]

> 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.

Personally I would go for geom_mirror. See gmirror(8) ('man gmirror') for usage
instructions including examples. Creating a mirror takes only one command.

--
/ Peter Schuller, InfiDyne Technologies HB

PGP userID: 0xE9758B7D or 'Peter Schuller <peter.schuller@infidyne.com>'
Key retrieval: Send an E-Mail to [email]getpgpkey@scode.org[/email]
E-Mail: [email]peter.schuller@infidyne.com[/email] Web: [url]http://www.scode.org[/url]

[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: [url]http://www.hedron.org/[/url]

[Andy Firman]

On Sun, Feb 27, 2005 at 01:59:35PM +0000, Robert Slade wrote:

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

Someone else already recommended GEOM which I also recommend.
I just setup gmirror for the fist time and I am very impressed with it.
I did drive failure simulations for both ad0 and ad2 and was able to
reconstruct the mirror each time. This howto is very good:

[url]http://people.freebsd.org/~rse/mirror/[/url]

Andy

[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