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Old 11-19-2009, 05:30 PM
Craig White
 
Default New install RAID 1+0

I have a new server to setup. 4 hard drives and I had intended it to be
hardware raid but that's a long story.

Does it make sense to set up the first two hard drives with RAID-0
partitions and then get through the install and then go back later and
then create identically sized RAID-0 partitions on the other two drives
and finally create the RAID-1 mirror from the first to the second?

Craig


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Old 11-19-2009, 05:42 PM
John R Pierce
 
Default New install RAID 1+0

Craig White wrote:
> I have a new server to setup. 4 hard drives and I had intended it to be
> hardware raid but that's a long story.
>
> Does it make sense to set up the first two hard drives with RAID-0
> partitions and then get through the install and then go back later and
> then create identically sized RAID-0 partitions on the other two drives
> and finally create the RAID-1 mirror from the first to the second?
>

are we to assume that your 'long story' involves this *not* being
hardware raid? so you're setting this up with mdraid? or what?

if mdraid, I'd probably boot the CD (or PXE) to rescue mode, use fdisk
and mdadm to partition and raid the drives as you like, then reboot the
CD/PXE into normal install mode, and install onto the md devices you
pre-created.

oh, and you normally build two mirrors (raid1) then stripe them together
(raid0) rather than the other way around.


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Old 11-19-2009, 05:47 PM
Ron Loftin
 
Default New install RAID 1+0

On Thu, 2009-11-19 at 11:30 -0700, Craig White wrote:
> I have a new server to setup. 4 hard drives and I had intended it to be
> hardware raid but that's a long story.
>
> Does it make sense to set up the first two hard drives with RAID-0
> partitions and then get through the install and then go back later and
> then create identically sized RAID-0 partitions on the other two drives
> and finally create the RAID-1 mirror from the first to the second?

I suggest that you consider LVM over RAID 1.

Since you have 4 disks, I would make a small RAID 1 on your first two
disks ( or if you are using IDE disks, the primary and secondary
masters ) to be /boot ( GRUB doesn't work with booting directly from
LVM ) and then create one or more RAID 1 devices in the remaining space.
You then use the RAID 1 devices as physical volumes in the LVM setup,
and create logical volumes however you wish.

My own "personal opinion" is that I use one RAID 1 device to support a
volume group that I call "sysdisk" and use for "system" filesystems such
as /, /var, /tmp, and swap. I use any additional RAID 1 devices in a
volume group I call "export" and put all of my data ( home directories,
downloaded audio/visual media, ISO images, etc. ) in logical
volumes/filesystems there.

One of the benefits of LVM is that you can have more than one physical
volume ( PV ) in a volume group, which will let you construct logical
volumes ( LV ) that are larger than your hard disks. You can also
resize LVs/filesystems and do some other useful things.

My $0.02 (US) worth.

>
> Craig
>
>
--
Ron Loftin reloftin@twcny.rr.com

"God, root, what is difference ?" Piter from UserFriendly

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Old 11-19-2009, 05:50 PM
Craig White
 
Default New install RAID 1+0

On Thu, 2009-11-19 at 10:42 -0800, John R Pierce wrote:
> Craig White wrote:
> > I have a new server to setup. 4 hard drives and I had intended it to be
> > hardware raid but that's a long story.
> >
> > Does it make sense to set up the first two hard drives with RAID-0
> > partitions and then get through the install and then go back later and
> > then create identically sized RAID-0 partitions on the other two drives
> > and finally create the RAID-1 mirror from the first to the second?
> >
>
> are we to assume that your 'long story' involves this *not* being
> hardware raid? so you're setting this up with mdraid? or what?
>
> if mdraid, I'd probably boot the CD (or PXE) to rescue mode, use fdisk
> and mdadm to partition and raid the drives as you like, then reboot the
> CD/PXE into normal install mode, and install onto the md devices you
> pre-created.
>
> oh, and you normally build two mirrors (raid1) then stripe them together
> (raid0) rather than the other way around.
----
yes, mdraid

OK, noted... make them in raid-1 first - I gather all of the mdadm
commands will have to be done in the shell prior to install.

Thanks

Craig


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Old 11-19-2009, 05:54 PM
Benjamin Franz
 
Default New install RAID 1+0

Craig White wrote:
> I have a new server to setup. 4 hard drives and I had intended it to be
> hardware raid but that's a long story.
>
> Does it make sense to set up the first two hard drives with RAID-0
> partitions and then get through the install and then go back later and
> then create identically sized RAID-0 partitions on the other two drives
> and finally create the RAID-1 mirror from the first to the second?
>

No. That just makes it so that if you have a failure you won't be able
to boot, which kind of defeats the point of having a RAID array. Make
your /boot partition a RAID1 partition right off the bat. That is so you
can tell GRUB to boot from any of the drives. You can choose RAID10
directly for the rest of your drive with the 5.4 installer.

--
Benjamin Franz

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Old 11-19-2009, 06:02 PM
Craig White
 
Default New install RAID 1+0

On Thu, 2009-11-19 at 10:54 -0800, Benjamin Franz wrote:
> Craig White wrote:
> > I have a new server to setup. 4 hard drives and I had intended it to be
> > hardware raid but that's a long story.
> >
> > Does it make sense to set up the first two hard drives with RAID-0
> > partitions and then get through the install and then go back later and
> > then create identically sized RAID-0 partitions on the other two drives
> > and finally create the RAID-1 mirror from the first to the second?
> >
>
> No. That just makes it so that if you have a failure you won't be able
> to boot, which kind of defeats the point of having a RAID array. Make
> your /boot partition a RAID1 partition right off the bat. That is so you
> can tell GRUB to boot from any of the drives. You can choose RAID10
> directly for the rest of your drive with the 5.4 installer.
----
yes, I understand about /boot

I didn't know that RAID-10 was an option now in the installer...problems
are solved

Thanks

Craig


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