How Can I Create Raid In Redhat As?

jedipi

Dec 21 2005, 12:52 PM

hi,
i want to create RAID5 in redhat as server.How can i do it?
what is the advantage of software RAID compare to Hardware RAID.
Which is better?

Thand you

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PureHeart

Dec 21 2005, 01:24 PM

RAID can be configured during the graphical installation of Red Hat Linux or during a kickstart installation. These instructions are for Disk Druid interface.

1.On the Disk Partitioning Setup screen select Manually partition with Disk Druid.

2.Choose New to create a new partition.

3.Choose software RAID from the File System Type pulldown menu
You will not be able to enter a mount point (you will be able to do that once you have created your RAID device).

4.Enter the size that you want the partition to be.

5.Select Force to be a primary partition if you want the partition to be a primary partition.

6.Click OK to return to the main screen.

Repeat these steps to create as many partitions as needed for your RAID setup.

That's all for RAID config.

About the differences between Software and Hardware RAID. The software RAID is like a emulator. And the hardware one, It's based on hardware, only enable if your hardware support it.

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yordan

Dec 21 2005, 06:58 PM

by the way, jedipi, how many hard disks do you have ? Because you need at least three disks (opmtimally five disks) in order to create a RAID5 disk. If you have only two disk, you create a raid1 disk or a mirrored pair.

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qwijibow

Dec 21 2005, 07:19 PM

QUOTE

what is the advantage of software RAID compare to Hardware RAID.
Which is better?

Hardware raid is better.

Software RAID is like RAID emulation for people who dont have hardware RAID.

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yordan

Dec 22 2005, 10:28 AM

I agree with qwijibow.
Moreover,
If you create a hardware RAID5 group, you can partition your disk, and then use it under Windows as well as under Linux.
Else, if you prefer software RAID, you will have a RedHat-only system, and you will loose a part of the openness and collaboration possibility of your PC.
Regards
Yordan

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jedipi

Dec 25 2005, 06:00 AM

Thank you for you guys help.
I have done it ....

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yordan

Dec 25 2005, 12:10 PM

Hurray ! congratitulations to jedipi and to each of us.

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abhay

Feb 28 2007, 05:38 AM

QUOTE(jedipi @ Dec 21 2005, 06:22 PM)

hi,
i want to create RAID5 in redhat as server.How can i do it?
what is the advantage of software RAID compare to Hardware RAID.
Which is better?

Thand you

1. Run fdisk on your hard disk, converting your partition to RAID AUTO(type 0xfd). Save changes and reboot.
Remember that the example is assuming your partition are /dev/hda9, /dev/hda10, /dev/hda11 and /dev/hda12. your actual partitions may wary.

2. initialze your RAID array:

# mdadm -- create /dev/md0 --level=5 --raid-devices=4 /dev/hda{9, 10, 11, 12}

this will aslo start the array. The array will immediately begin the construction process, but it can be used immediately. In a spare terminal window, run watch cat /proc/mdstat to keep an eye on the progress of array construction.

3. While waiting for this process to complete. we can start using RAID device. format the partition with an ext3 file system. We will use 4k blocks.

# mke2fs -j -b 4096 -R /dev/md0

4. See if you can mount /dev/md0 /data. This command should work, even if the array is still building.

5. The mdadm --detail command can be used to display used to display useful information on the state of your RAID devices. Try out this command, mdadm --detail /dev/md0.

6.Try creating some files in it /data. Add entry to /etc/fstab and test mounting and unmounting the file system.

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