Hello,

Sorry if this is in the wrong group. I couln't find one specific for
LVM.

If I install Linux on a 3-disk software RAID5 system with partitions
SWAP and / will I then later be able to install LVM on this system and
put /home /usr /var (and others) onto LV's or will I have to do this
when installing the system?

Any good tutorial on how to do this? Or maybe a good tutorial on how
to install Debian with both
RAID5 and LVM?

I'm asking because I need to learn RAID first and then move on to LVM
on RAID, but I would like to avoid backing up and reinstalling
everything


Thanks
/Peter

Peter wrote:

> If I install Linux on a 3-disk software RAID5 system with partitions
> SWAP and / will I then later be able to install LVM on this system and
> put /home /usr /var (and others) onto LV's or will I have to do this
> when installing the system?

Much depends on how your slices will look like, if you slice up your
raid at install time, then you will need a extra storage while you
convert a slice to LVM, as this means you will loose all data on it, so
you need to store it somewhere else and then copy it back afterwards.

I do suggest you do the LVM during install, this is usually simplest, as
most modern distributions do have this step as optional during fresh
installation, create the slice for boot and another for the LVM and then
dedicate space out of the LVM to the different "slices" you want to use,
I do suggest you pick reiserfs or ext2/3 as the file system, as jfs and
xfs won't support shrinking the volume size.



> Any good tutorial on how to do this? Or maybe a good tutorial on how
> to install Debian with both
> RAID5 and LVM?

I'm not much into debian, but if you want to do the hard way, then read
first the SoftRAID howto and then jump on LVM howto, but in general you
don't need to raid when using LVM, as you can both stripe and mirror in
LVM and I don't see much of a point using raid as an extra layer and
possible extra trouble if something bad would happen.


> I'm asking because I need to learn RAID first and then move on to LVM
> on RAID, but I would like to avoid backing up and reinstalling
> everything

use a modern distribution and everything will be simple to do during
install, I could suggest Fedora or CentOS to get the simplicity.

--

//Aho

Hi Peter

Peter wrote:
> Hello,
>
> Sorry if this is in the wrong group. I couln't find one specific for
> LVM.

NG is good...

> If I install Linux on a 3-disk software RAID5 system with partitions
> SWAP and / will I then later be able to install LVM on this system and
> put /home /usr /var (and others) onto LV's or will I have to do this
> when installing the system?

Do it when installing the system or it will take a lot of time afterwards

> Any good tutorial on how to do this? Or maybe a good tutorial on how
> to install Debian with both
> RAID5 and LVM?

With Debian it is straightforward. Follow the instructions of the text
based installer. First partition all 3 disks with 2 partitions
(identical size in all the disks), one small for raid1 /boot, and one
bigger for raid5 LVM. Then configure LVM and through the installer and
make in it: /, /home, /tmp, /var and all the rest you want.

> I'm asking because I need to learn RAID first and then move on to LVM
> on RAID, but I would like to avoid backing up and reinstalling
> everything
>
>
> Thanks
> /Peter

On Apr 20, 4:35*pm, linuxnewbie1234 <linuxnewbie1...@nowhere.com>
wrote:
> Hi Peter
>
> Peter wrote:
> > Hello,
>
> > Sorry if this is in the wrong group. I couln't find one specific for
> > LVM.
>
> NG is good...
>
> > If I install Linux on a 3-disk software RAID5 system with partitions
> > SWAP and / will I then later be able to install LVM on this system and
> > put /home /usr /var (and others) onto LV's or will I have to do this
> > when installing the system?
>
> Do it when installing the system or it will take a lot of time afterwards
>
> > Any good tutorial on how to do this? Or maybe a good tutorial on how
> > to install Debian with both
> > RAID5 and LVM?
>
> With Debian it is straightforward. Follow the instructions of the text
> based installer. First partition all 3 disks with 2 partitions
> (identical size in all the disks), one small for raid1 /boot, and one
> bigger for raid5 LVM. Then configure LVM and through the installer and
> make in it: /, /home, /tmp, /var and all the rest you want.

Thanks both of you for answers.

Based on what J.O. Aho wrote, I'm wondering, is there are any benefits
of LVM on top of RAID1 or 5?


Thank again
/Peter

> Based on what J.O. Aho wrote, I'm wondering, is there are any benefits
> of LVM on top of RAID1 or 5?

You can make multiple partitions over a RAID only if you use LVM.

Do not use LVM for /boot, I think the bootloader is not able to read LVM
while it is able to read raid1 with 1 ext2/3 partition directly over it.
(Grub).

On Apr 21, 5:05 am, linuxnewbie1234 <linuxnewbie1...@nowhere.com>
wrote:
> > Based on what J.O. Aho wrote, I'm wondering, is there are any benefits
> > of LVM on top of RAID1 or 5?
>
> You can make multiple partitions over a RAID only if you use LVM.
>
> Do not use LVM for /boot, I think the bootloader is not able to read LVM
> while it is able to read raid1 with 1 ext2/3 partition directly over it.
> (Grub).

I assume you are using a RAID solution provided by your mother board.
This is software RAID. The biggest problem is whether dmraid, used by
Linux, can see your array. I have an Intel ICH8R chip set and was able
to install SUSE 10.3 and fedora 8 in an LVM built during installation.
You should be able to do the same thing with ubuntu if you use the
'alternate' CD.
The problem came when I changed from RAID0 to RAID5. I have found out
that dmraid can't work with RAID 5 & 10 on my chip set.
My suggestion, as a first step, is to boot to Knoppix and see if it
can see your array. If it can't use the package manager to make sure
'dmraid' is installed, I think it is by default.
If you can't see it you need to look some more with Google.
If you can see it create your LVM during installation.
If you plan to dual boot with Windows there are partitioning issues
Your are correct that at least /boot needs to be in a separate non
LVM partition. some people will tell you not to put root in an LVM but
I haven't had a problem with that unless you're moving an existing
distribution.

jim wrote:
> I assume you are using a RAID solution provided by your mother board.

My suggestion is to NEVER use the raid from the mother board. Always use
software raid from linux mdadm. It is faster, has known partition header
and data format specifications, proven reliable, raid level up to 6.