Raid , before os install or after os install ?
 

Hai to all

I have configured software raid 5 during fedora installation process . It works fine and it is a fault tolerant .

but when i configured raid 5 after os installation by using mdadm, it does not seem to fault tolerant . If any of the drive fails in array whole raid partition is failed .

Please suggest me some idea to configure raid 5 after os installation

You want to use mdadm (soft raid) or you are using some raid controllers ?

Thanks for your quick response

I dont have hardware raid controllers . I want to configure only by using mdadm

Can you give more details about your hdd structure. Where is root partition and where is raid5?

I have configured Raid 5 in my fedora system during the graphical os installation process for that i selected 3 harddrives.This raid5 configuration includes /boot, /, partitions.every thing was
fine.

Just for testing purpose, I removed one harddrive from the raid5 array.still the system works fine. I got happy, Then i moved to configure from commandline using mdadm ....

Now i have 4 harddisk(sda,sdb,sdc,sdd). sda is not in raid5 array it consist of /boot /,and swap partitions formatted with ext3 filesystem . I took rest of three drives to configure raid5(sdb,sdc,sdd).

Using fdisk i formatted (sdb,sdc,sdd) to fd filesystem ....

The following commands i used ...

[root@test]# mdadm --create --verbose /dev/md0 --level=5 --raid-device=3 /dev/sdb1 /dev/sdc1 /dev/sdd1 .

then i got "mdadm: array /dev/md0 started " message


[root@test]# cat /proc/mdstat
.
.
.
[3/3][UUU]


[root@test]# mkfs.ext3 /dev/md0

[root@test]# mdadm --detail --scan --verbose > /etc/mdadm.conf

[root@test]# vi /etc/fstab

/dev/md0 /raidtest ext3 defaults 1 2

[root@test]# mount -a

Then i rebooted my system .

The /raidtest partition is successfully mounted ...( I got happy )

For testing purpose i removed one harddrive from the raid5 array, But my system is not booting.

I got the error messages as follows :

fsck.ext3 : Invalid argument while trying to open /dev/md0
/dev/md0:
The superblock could not be read or does not describe a correct ext2 filesystem .
.
.
.
.
Give root password for maintenance
(or type control-D to continue):

why this happened ?

where did i made mistake ?

This dosen't happened in graphical OS installation process(Fedora DVD) of raid5 configuration ..

any suggestions will help me

Thanks in advance to all ....

Just to confirm, you created the raid from ssdb, ssdc and ssdd AFTER you had booted the original system configured under the Fedora GUI system? You were running this system when you re-created the RAID volume /dev/md0? I'm confused :confused: If you created the RAID while running the OS, didn't you just format md0 which means that you've just overwritten your initial system? (apart from the /boot on ssda which contains the kernel)
You need to initialise disks and RAID systems BEFORE you load an OS surely?

Maybe I've missed something in what you've written...

Play Bonny :hattip:

Thanks for your response

let me explain clearly . What i did is that i took 4 new harddisk attached to my system , inserted my fedora dvd started graphical installation process .
During graphical installation process i clicked raid button to create raid 5 everything was in GUI . It worked fine .


task 2 : now i selected another system attached only one harddrive and i installed fedora os. After installation Then i attached 3 more new harddisk . By using command line(mdadm) i started to configure raid 5 but it is not showing fault tolerant

Ah! Your system is loaded on ssda. The RAID is then set up on ssdb, ssdc & ssdd. Sorry, I misunderstood. Did the system boot OK when you re-inserted the disk? Does the system keep running if you pull the disk when it's up? (Oh! painfull... :eek: )

Play Bonny! :hattip: