How to Raid 5 with 5 drives

[carltonb]

I have a machine set up that houses 5 drives.

Drive 1 is a 500g, while drives 2,3,4,5 are all 1TB.
I want to use the 500g drive for the program, while 2-5 are for a Raid 5 setup.

Can any one point me in the direction of a post or article on how to set it up.

Thanks
carltonb

[moredruid]

Well, just install everything as per the instructions on the Amahi site. Leave the disks you want to use as the RAID 5 set untouched.
When the install is finished you can create the RAID array as follows (if you've installed your OS on /dev/sda):
*work as root on a terminal*

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mdadm --create /dev/md1 --level=5 /dev/sd[bcde]

Then save the config to disk:

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mdadm -D -s > /etc/mdadm.conf

Create a volume group with a logical volume on the disk for you data:

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pvcreate /dev/md1 vgcreate vgdata /dev/md1 vgdisplay

Here you will see the output of the volume group, note the "free PE" number and put that number behind the -l option in the lvcreate line:

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Free PE / Size 2305 / 9.00 GB lvcreate -l 2305 -n lvdata vgdata mkfs.ext4 /dev/vgdata/lvdata

I chose the ext4 filesystem, but if you want a different filesystem (ext3, reiserfs, xfs) you can do that if you want, you just need to substitute the mkfs command with the option you want.
Now we need to set it all up so you can actually use it. First we need to temporarily copy everything in /var/hda/files to a different folder:

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mkdir /tmp/tempfiles mv /var/hda/files/* /tmp/tempfiles

Now we test the filesystem:

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mount /dev/vgdata/lvdata /var/hda/files mount

You'll see that the logical volume is mounted on /var/hda/files. You can also type "df -h" and you'll see that /var/hda/files has tons of free space.
Now we move the files back to where they belong:

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mv /tmp/tempfiles/* /var/hda/files

Last part: unmount the filesystem and make sure that the disks are mounted at boot time:

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umount /var/hda/files cp /etc/fstab /etc/fstab.backup echo "/dev/vgdata/lvdata /var/hda/files ext4 defaults 1 2" >> /etc/fstab

Make sure the whitespace is preserved when copying the last line!
Check if the line has been added correctly & mount the filesystem

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cat /etc/fstab mount -a

If you get no errors on the last command (mount) the filesystem is up and will be brought back up at subsequent bootups.

[marcel]

I do not want to hijack this topic, but i have also a few question about raid, spin down raid arrays, rebuilding raid arrays. You now a lot about Linux moredruid. I will open a new topic for these questions when i have time.

[moredruid]

sure, shoot...

it might indeed be interesting to have some kind of reference for setting up RAID.