FC5 install with RAID 1 - tutorial ??

[bluejuice]

I have made several attempts to configure a RAID 1 Array (mirror 2 hdd) via the FC5 installation options, but I always get "this option is not possible". Does anyone have any advise or know of any step-by-step tutorials for this?

[pparks1]

Start a standard install. When you get to the Linux partitions screen, you should see your 2 hard drives listed. Change from "Remove linux partitions on selected drives and create default layout" and instead use "Create Custom Layout" Click on Next.

Highlight the free space on /dev/hda.
Select New
Change file system type to "software RAID"
Under allowable drives, ONLY choose /dev/hda
Choose your desired size
click on ok.

Highlith the free space on /dev/hdb
Select New
Change file system type to "software RAID"
Under allowable drives, ONLY choose /dev/hdb
Choose your desired size
click on ok.

Repeat those steps above for whatever RAID partitions you want to setup. If you want /home and /var to be RAID, you will do the above steps twice

Now, click on RAID
Choose Create a RAID Device (default = /dev/md0} and click on Ok.
Define a mount point
Set file system type (i chose ext3)
Set Raid Device to md0
Set RAID level to RAID1
Choose both of your RAID members (hda and hdb)

Repeat these steps for however many partitions you decided to setup using RAID1.
select OK.

Click on Next to Continue with remainder of installation

[bluejuice]

pparks1 appreciate the support - wont have a chance to make another trial for a couple of days but will give your instructions a go and hopefully close this thread on a high note.

[ltam]

I tried to install RAID 5 with 2 - 80 gig ide drives.
I followed these steps to create 3 RAID partition on both drives for /, /home, /var. The remaining was created for swap. Is it correct to create a swap on both drives. Will having swap on both drives cause problems? Basically, both of my drives have exact image partitions.

Thanks.

By the way, thanks to pparks1 for writing the tutorial. I cannot find anywhere a set of step by step instructions to describe this. It's not difficult but every book that I go to describes it differently. They either go into RAID theory or dismisses the topic altogether.

[ltam]

Can someone please tell me how I can check if my raid drives are working properly?

[pewterdragn]

Run this in a terminal:

cat /proc/mdstat

For RAID1/0 arrays, if you see:

md0 : active raid1 sdb1[1] sda1[0]
         128384 blocks [2/2] [UU]

or similiar you are ok. If you see something like:

md0 : active raid1 sdb1[1] sda1[0]
         128384 blocks [2/1] [U_]

then that array is broken. The [2/1] says you have one partition down and the [U_] is a representation of that. If you see something like:

md4 : active raid1 sdb6[2] sda6[0]
      117354688 blocks [2/1] [U_]
      [>....................] recovery = 0.0% (27264/117354688) finish=143.2min speed=13632K/sec

then that array is repairing itself (resync).


RAID5 arrays are the same but with different amount of disks (and RAID config):

md3 : active raid5 sda5[0] sdb5[0] sdc3[2] sdd3[3]
         441609984 blocks level 5, 256k chunk, algorithm 2 [4/4] [UUUU]

[ltam]

Wow, thanks Pewterdragn for the quick response and the great detail in your response. Mine is showing 2/2 as it should since I just installed it. Terriffic!!!!

Thanks again.

[ltam]

I don't know if I'm imagining this but I'm running CentOS4 on my Duron 1.7GHz box with 512 meg of RAM and 2 x 80 gig mirrorr drives and it seems to be performing better then when it was only one drive. Is that possible?

[pewterdragn]

very possible. when reading data (not writing) you are reading from both disks at once (there is some overhead - its not 2x faster).

[PinkZeppelin]

I followed pparks instructions for the software RAID on my FC4 machine.

I just wanted to check if what I have done is correct and in theory should work.

I have 2 80gb hard drives so I created a RAID 1 array with md0 which is my /boot device.
Then I created a /swap partition (but I did not mirror this with RAID 1 on the other hard drive, and instead I just created another swap partition on the other hard drive with the same size). Then I used the additional space on each hard drive to create a RAID 1 array, md1 which contains /

Is this correct? Will both drives be bootable and will swap work even though I did not mirror the swap partition? Any Recommendations?

Thanks

[jonmyatt]

You should mirror the swap too, otherwise if you lose the disk with the swap on, your system won't be happy...

[PinkZeppelin]

Thanks jonmyatt. I ended up reinstalling fedora and mirrored /swap.

Just to conclude this topic could someone please tell me what you have to configure or change with grub in order for the mirrored drive to be bootable.
Meaning, if I unplug the 1st drive, how will the second work. I heard you have to configure grub for this or instead use lilo. I would rather use grub, however, so can someone list the changes you need to make in order to make both drives bootable.

Thanks

[jonmyatt]

Have a look here:

http://www.dirigo.net/tuxTips/avoidi.../GrubMdMbr.php

basically you need to get grub to write an MBR to the 2nd drive.

Jon.

[bluejuice]

I have finally had some time freed up to experiment with RAID1 installation.

My objective is to configure raid 1 mirror on a running system (post installation) which was default installed with Fedora 4 onto 2 x 80G harddrives. I attempted to follow a guide that detailed a method of removing the second drive from the Volumn Group and change the partition ID to fd (raid autodetect) then create a Raid dev md0 with mirror partition 'missing'. Move the data from the existing partition of the new raid partition, change the ID on and add the missing partition. Supposedly this could all be done without rebooting.

However I ran into an immediate hurdle when I discovered that the default installation had not actually physically partitioned the drives but instead had created a boot partion on hda and the remaining space on hda and the entire of hdb were partitioned as LMV physical volumes as part of the VolGroup00. Therefore since the boot partition effectively made the PV of hda smaller than the PV of hdb, I was not able to pvmove and thus could not figure out how to remove hdb from the VolGroup00.

[psmith811]

Originally Posted by jonmyatt

Have a look here:

http://www.dirigo.net/tuxTips/avoidi.../GrubMdMbr.php

basically you need to get grub to write an MBR to the 2nd drive.

Jon.

is this true if the /boot partition is on say /dev/md0 ?