using mdadm with different capacity drives in raid 5

Using mdadm with different capacity drives in RAID 5?

location: linuxquestions.com - date: August 10, 2009
Hi all, I am going to soon setup a RAID 5 configuration for a server with mdadm. However, I am hoping to use the following configuration: 4x1TB SATA 3Gb/s HDD with 2x500GB SATA 3Gb/s HDD in a RAID 5 configuration. If this works as I imagine it, I should be left with about 3.5TB of total space. I am thinking it might be possible to create a striped array with the 2 500GB drives so the system sees 5x1TB HDDs. The reason I want to do this is simple, to achieve the highest capacity while remaining some failure redundancy. I bought the 1TB drives to use in this configuration specifically and the 500GB drives would essentially be unused by me any longer, sitting in the closet or under-appreciated in a workstation somewhere. Impossible? Please lend me your assistance!

Creating RAID 5 with 2 disks using mdadm

location: linuxquestions.com - date: October 10, 2008
Hi, I am using mdadm to emulate s/w raid on my system. I am trying to create a RAID 5 configuration on my system. I have 4 disks, each of X GB, with me. I can create a raid 5 by the following command: mdadm --create --level 5 --chunk 4 --raid-devices 3 --spare-devices 1 --run /dev/md0 /dev/sdb /dev/sdc /dev/sdd /dev/sde The above command creates a perfect raid. By the definition definition of RAID 5, it requires minimum of 3 disks (excluding spare disk) for its configuration. RAID-5 is nothing but RAID-0 with distributed block level parity. Now, if I try to create RAID 5 with the following command: mdadm --create --level 5 --chunk 4 --raid-devices 2 --run /dev/md0 /dev/sdb /dev/sdc It still goes ahead and creates a RAID 5 with just two disks. That means it is using one disk of writing data & other for parity. Is this right? Shouldn't mdadm fail, when we provide only 2 disks to create RAID-5? Though it keeps intact other raid-5 configuration. Say,

Help with deleting RAID 0 using MDADM

location: linuxquestions.com - date: January 25, 2012
Hi all, I'm using MDADM to create a Raid0 array (2 disks), which I have done successfully. Now I want to add another two disks and make a Raid5. I've tried using --remove to delete disks from Raid0 array and delete it but now I realise this can't be done in Raid0. So is it safe to just delete the super-block and make a Raid 5? Do I need to stop the array first? I think I need to delete Raid0 array first but how do I this? Step by step instructions would be really helpful. Thanks in advance for any help.

Need Urgent Help With Software RAID Using mdadm Data Recovery Issue

location: linuxquestions.com - date: September 16, 2015
Hello, I need help with a situation that i am trying to resolve. Let me give some background to provide as much information as possible. I have the 15.04 version of Ubuntu installed. My goal is to reconstruct a software RAID 0 array that I had existing on a Western Digital My Book Studio II (4 TB) external hard drive (these were it's default settings). There was an issue with the controller on the hard drive and it was no longer recognized by any OS (I tried 4 different ones), but the data on both 2 TB drives remained intact. I took the drives out and put them in two external USB 2.0 enclosures and connected them to my Ubuntu setup. I then ran the command: sudo mdadm --create /dev/md0 --level=0 --raid-disks=2 /dev/sdc /dev/sdd believing that this would "pull" the information from the existing RAID setup and place it on the newly mounted "md0" partition. It seemed that someone else had done this successfully on another forum, so I thought this was the cor

Dual Boot Windows 7 and Ubuntu using 2 Different Hard Drives

location: linuxquestions.com - date: November 23, 2010
Hello, I just started working with Linux over the weekend. I do have a working dual booting system but it's not configured exactly how I want it to be. Currently Windows 7 Ultimate and Ubuntu are on the same hard drive but different partitions. The Windows boot screen comes up and I can select Windows or Ubuntu fine. Grub comes up when I select Ubuntu and I can successfully select any choice in the menu and it will run properly. Everything works great now so you may wonder why I even want to keep tinkering, well, it's not working how I want it to. This is what I want it to do. I want Windows 7 on disk 0 and Ubuntu on disk 1. I want each OS to have it's own hard drive. I want Grub to be the only boot loader that comes up with the option to select Ubuntu or Windows. I want to skip the window's OS selection screen all together. I can modify Grub, I've already done some of that on my work computer. I've been installing from windows. Should I use a CD instead? Would th

How to do I install ubuntu on a raid 5 using mdadm?

location: ubuntuforums.com - date: August 18, 2013
Hello, I want to install Ubuntu 13.04 (not server), I have 4 empty hard drives (/dev/sda, /dev/sdb, /dev/sdc, /dev/sdd), each 150 gb and /sdd is160 gb and I have a Live USB. I want to install Ubuntu on a RAID 5 array using mdadm. What exactly do I need to do? I made four ext4 filesystems and four swap partitions and created an array (of all 8), but after install it didn't boot. And on this thread (http://ubuntuforums.org/showthread.php?t=408461), I read something about a separate /boot partition, but I don't really get that. Can someone explain this please? I understand the problem but I don't know how to solve it. Thanks

HOWTO: Linux Software Raid using mdadm

location: ubuntuforums.com - date: April 13, 2007
1) Introduction: Recently I went out and bought myself a second hard drive with the purpose of setting myself up a performance raid (raid0). It took me days and a lot of messing about to get sorted, but once I figured out what I was doing I realised that it's actually relatively simple, so I've written this guide to share my experiences I went for raid0, because I'm not too worried about loosing data, but if you wanted to set up a raid 1, raid 5 or any other raid type then a lot of the information here would still apply. 2) 'Fake' raid vs Software raid: When I bought my motherboard, (The ASRock ConRoeXFire-eSATA2), one of the big selling points was an on board raid, however some research revealed that rather than being a true hardware raid controller, this was in fact more than likely what is know as 'fake' raid. I think wikipedia explains it quite well: http://en.wikipedia.org/wiki/Redunda...ependent_disks Hybrid RAID implementations have become very popula

Software Raid 5 (md) recovery using mdadm

location: linuxquestions.com - date: May 6, 2007
Hello, after receiving the following errors from two of my four disks in my md0-array Code:

HOWTO: Linux Software Raid using mdadm

location: ubuntuforums.com - date: April 13, 2007
1) Introduction: Recently I went out and bought myself a second hard drive with the purpose of setting myself up a performance raid (raid0). It took me days and a lot of messing about to get sorted, but once I figured out what I was doing I realised that it's actually relatively simple, so I've written this guide to share my experiences I went for raid0, because I'm not too worried about loosing data, but if you wanted to set up a raid 1, raid 5 or any other raid type then a lot of the information here would still apply. 2) 'Fake' raid vs Software raid: When I bought my motherboard, (The ASRock ConRoeXFire-eSATA2), one of the big selling points was an on board raid, however some research revealed that rather than being a true hardware raid controller, this was in fact more than likely what is know as 'fake' raid. I think wikipedia explains it quite well: http://en.wikipedia.org/wiki/Redunda...ependent_disks Hybrid RAID implementations have become very popula

Dual boot with two hard drives using bcdedit (not grub)

location: ubuntuforums.com - date: January 31, 2010
Hi, I have successfully installed Ubuntu 9.10 on a second hard drive (/dev/sdb). I already had Windows 7 installed on first hard drive (/dev/sda). /dev/sdb is partioned into 3 partitions. /dev/sdb1 is formatted with ext4 and mounts /, /dev/sdb2 is swap area and /dev/sdb3 i a formatted ntfs partition for OS sharing. GRUB is installed into the MBR of /dev/sdb. I am able to boot Ubuntu if I tell my laptop (Lenovo Thinkpad T60) to boot from my second hard drive. However, I would prefer to have my Windows boot loader (bcdedit) recongize Ubuntu so I could select Ubuntu from there. I am not able to get this to work. When I select Ubuntu on the boot manager menu I get black screen displaying GRUP in the upper left corner and a blinking cursor. I have followed the paragraph "Configuring for Dual Boot" in http://www.iceflatline.com/2009/09/h...using-bcdedit/ which seems to work for most people. However, it seems that most people have a single hard drive scenario and that mi