A linux utility used to manage software RAID devices.

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How to restore RAID5 Array

I have a RAID5 array consisting of 3 identical 2TB drives. Suddenly GRUB wouldn't boot anymore and gave the error out of disk. Eventually booted a livecd and ran some mdadm commands: mdadm --examine ...
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236 views

Raid 5 rebuild with wrong stripe size & no failed disks - is data lost?

I'm curious if there are hidden complexities to RAID5 and RAID5 rebuilds. My understanding is that (in a 3 disk array) a rebuild would just directly compute the parity of disks 1 & 2 and write ...
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1answer
907 views

mdadm: /dev/md0 assembled from 3 drives - not enough to start the array

I had a drive in my raid5 fail a while back. I believe the problem was due to a power failure at the time, but originally thought it might be the hard drive controllers on the motherboard. (this is ...
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103 views

mdadm RAID10 - change broken disk

Tonight my server stopped answering to ssh, ping, so I drove to the server room. Server did not respond to keyboard (even Ctrl-Alt-Del), there was no data on screen (it was black, no symbols on it), ...
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395 views

RAID boot drive not found after mdadm upgrade

I was having trouble getting a new RAID array to assemble on startup, and before anyone responded to that post, I tried updating mdadm, but this ended up taking a very long time because of all the ...
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723 views

Revert btrfs to ext4 on mdadm raid

I have a Raid 5 setup using devices rather than partitions. I recently converted the ext4 fs on the md device to btrfs. I was initially happy with btrfs, but to be short, it's eating up CPU cycles ...
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169 views

mount mdadm disk without partition table

I've a debian installation and during the installation I had made 3 mdadm raid disk: swap, root and home. I had done it with partman and it had made the mdadm disk without partition table. Now I want ...
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279 views

Removing failed disk from raid 1

my server (Debian Wheezy) has a failed disk. I have sda and sdb and according to the support of my hoster, sdb needs a replacement. I send them this information with the mdstat: http://pastebin.com/...
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2k views

“Spare” disk in a 2-disk mdadm RAID1 array?

I recently had a RAID1 volume fail. It had three primary partitions in it, all participating in separate, but similarly configured VGs. This configuration comes from the fact that the machine is ...
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6k views

Linux md RAID: /dev/md0 vs. /dev/md/0

On newer systems /usr/share/mdadm/mkconf (the script that is used to generate /etc/mdadm/mdadm.conf) tends to use the device name /dev/md/0 instead of /dev/md0: new-system ~ # /usr/share/mdadm/mkconf ...
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43 views

Getting a Windows 7 installation to run virtualized under Ubuntu?

I've currently installed Windows 7 and Ubuntu via dualboot. To avoid switching the OS by rebooting, i want to be able to start my Windows 7 via a virtual machine. It is important to be able to boot ...
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62 views

What chunks are mismatched in a Linux md array?

This is a repost of a question I asked on ServerFault and was automatically deleted for lack of activity. Let's hope it will have better luck here. After performing a "check" (by writing check to /...
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116 views

Boot GRUB2 with Degraded RAID5

I am building a custom NAS with Debian Jessie. Has three 4TB hard drives in a software RAID5 configuration. Works perfectly when all three drives are present. I am trying to test what happens when if ...
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54 views

CentOS 7: RAID 1 high I/O wait

I am running CentOS 7, with RAID 1 (md) on the hard drives. I have the partitions set as shown below. md0 -> root (sda1, sdb1) md2 -> swap (sda2, sdb2) md3 -> misc (sda3, sdb3) on md3, I ...
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256 views

Install CentOS on RAID (manually) on UEFI system

I'm struggling with the manual configuration of a RAID1 + RAID10. I'm trying the procedure on a VM (VirtualBox 5.0.14 r105127) on OSX 11.10.3. The strategy I took is: The complete set of commands I ...
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242 views

Degraded RAID1 array boots with one drive, not with the other

UPDATE It seems initramfs fails to properly mount the array. If I stop and reassemble them, they works: mdadm --stop /dev/md124 mdadm --assemble --run /dev/md124 /dev/sda6 Maybe initrd tries to ...
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330 views

RAID5 Arrary disappeard with no HW or SW changes made

I have a R-Pi running XBMC (Linux CaribNAS 3.10.24 #2 PREEMPT Mon Dec 23 05:18:12 UTC 2013 armv6l GNU/Linux) with a 3 disk raid 5 array that has been working up till yesterday when is stopped running ...
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740 views

Disable RAID auto detect at runtime

In Linux, I'm partitioning two disks for RAID1 with fdisk. The first disk partitioning succedes, but the second fail because the raid starts automatically and occupy also the second disk (why? it ...
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498 views

Software raid checksumming slow

On my new 24 disk array I get 900 MB/s of raw read or write using dd to all the disks. When I set the disks up as a 24 disk RAID6 I get 400 MB/s write and 600 MB/s read. It seems to be due to ...
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92 views

Assistance with mdadm.conf syntax for reassembly of existing RAID0

I'm trying to recover a friends data from a Sony Vaio VGN-AW47GH Laptop. It has a pair of Toshiba MK5055GS 2.5" 500GB HDD combined (according to my reading) into a 1TB RAID0. The laptop is no longer ...
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48 views

Debian boot with encrypted disks: RAID is not assembled

Situation I am running Debian 8 on my machine. The disk setup is as follows: # lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 55.9G 0 ...
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65 views

Why is uEFI firmware unable to access a software RAID 1 /boot/efi partition?

BIOS firmware can boot a BIOS formatted /boot partition installed on a software RAID 1 pair no problem. It can even boot from a /boot installed on LVM volume that lives on a software RAID 1 pair. But ...
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50 views

MD RAID 5 module doesn't load at boot

I recently upgraded my NAS to kernel 4.4 and now my md raid 5 array doesn't assemble itself at boot. dmesg reveals this: [ 2.299666] md: personality for level 5 is not loaded! and doing lsmod | ...
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96 views

Ubuntu Server: How to make bootable bios_grub RAID device?

I have a stable Ubuntu (14.04.3) Server-powered file server that I have set up, and want to set up a RAID10 array for it. For reference, I have been following this guide so far, but using RAID10 ...
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124 views

lsblk shows non-existent md partitions after reboot

I'm getting weird behaviour while setting up an mdadm RAID1 array on debian 8.2. After I set-up the array, lsblk shows: simon@debian-server:~$ lsblk NAME MAJ:MIN RM SIZE ...
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70 views

RAID5 needs drive to be added every reboot

I have a 3 disk RAID5 mdadm array total 4TB on an Ubuntu Server 14.04.3 LTS. Since a kernel panic caused by an already replaced device unrelated to the array, after every reboot the array starts [UU_]...
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48 views

RAID1 superblock recovery

I have a big issue with my RAID1 array. I transferred my RAID1 (mdadm) to a new PC, but when I was installing it, I rebuilt the array as a RAID0. No data has been written to the disks. When I try ...
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12 views

How to make mdstat ignore specified devices

I have a hypervisor with KVM that uses zvols for virtual machine storage. One such virtual machine was moved from a physical one and has software RAID inside it. Zvols are detected as block devices on ...
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47 views

mdadm arrays referencing the same devices

I've a software RAID setup for one of my servers. Now there are two arrays that reference the same devices (md126/md127 - see below) where one of them is marked inactive. I want to understand what ...
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139 views

MDADM Array Detection Slowing Down Boot - Why?

I have an AMD64 Gentoo (running systemd) build with a RAID0 root and some other arrays (RAID1 boot, RAID1 home etc..). The boot process is being slowed down quite dramatically as mdadm searches the ...
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Is it reliable to assemble md from two machines at the same time

Say we have the same disks accessible from two machines. I want to do assembling md from two machines. Is it possible/reliable ? The disks are connected through SAS. All I need to have is reliable ...
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824 views

Help with lost software RAID5 on CentOS 6.5

I've been searching for hours and giving up / too scared to delete all my data. I have a file server running CentOS 6.5 which has 4 WD RED 2TB drives (all > 1 year old) in software raid 5 with mdadm, ...
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376 views

How do you migrate from dmraid to mdadm on a working 14.04?

I installed 14.04 LTS the other day on two Samsung 840 Pro's in RAID0 on my Intel FakeRAID BIOS setup (NO efi). It is running great, however during the initial boot the system seemed to have a broken ...
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Linux software raid assembled “itself” with failed drive. Why?

I have two raid1 arrays: md3 (sda3 + sdb3) and md5 (sda5 + sdb5). I deliberately failed the sdb disks because I wanted to change the partition table: # mdadm /dev/md3 --fail /dev/sdb3 # mdadm /dev/...
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238 views

How to blacklist bad blocks from a MD-raid + dm-crypt + ext4?

I have a ext4 partition, on top of a dm-crypt, on top of a MD-RAID 10. One partition (/dev/sdc1) dropped out of the array with a ton of read errors. I ran the manufacturer provided diagnostic tool ...
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Help needed with Raid 5 that was working OK

My parents had a Netgear RN 104 that stopped working properly, they messed with some settings, messed it up and gave it to me to fix. It has 4 x 4tb drives in Raid 5. I've used mdadm before to ...
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23 views

Converting A Physical Ubuntu Server with boot raid 1 to a Xen domu

So here's the situation: 1 physical server running a very outdated version of ubuntu 14.04 Booting off of a a software raid 1 configured in the installation. This server runs mission critical ...
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42 views

What can slow down a RAID 5 with 3 disks recovery rate to sub-MB speeds?

I have a RAID 5 on 3 disks 4K aligned (2x WD2001FFSX and 1x WD20EFRX). One of the disks has failed, and i replaced it with an other WD2001FFSX. After partitioning it the same way than the other (1 ...
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41 views

RAID0 worse that write speeds of hard drives independently

So I have two hard drives one connect with SATA and one with USB3.0 SATA (/dev/sdc1): Apple HDD Toshiba USB (/dev/sde2): Western Digital Technologies, Inc. Elements SE Portable ...
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21 views

Applying a patch to mdadm

I have configured RAID 6 using mdadm, and after trying to add a new disk to the ARRAY (replacing a faulty one), I am receiving the following error: mdadm --manage /dev/md0 --add /dev/sdi mdadm: /dev/...
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45 views

Centos 7.2 Convert single LVM to RAID Mirror Reinstall BootLoader

I am trying to convert a single-drive Centos 7.2 installation with LVM into a two-disk mdadm mirror with mrrored LVM. I was able to follow the excellent instructions at: http://www.dgoradia.com/...
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26 views

mdadm does not automount raid0 disks under /media/storage

I've beat my head against this issue all night and I can't seem to wrap my head around it. I've recently installed Linux Mint 17.3 Mate to replace my Windows 10 machine and after some tinkering I've ...
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49 views

Mount existing RAID 5 to Open Vault Media but cannot see any file

I have an existing mdadm RAID5 pool with 3 disks running on Debian. When I connect this RAID5 pool to Open Media Vault (OMV), OMV recognise the pool and all information: disks, usage, free space.... ...
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mdadm raid 1 array superblock can't be ready

I have a ubuntu linux box, with a raid mirror, 2x3TB using mdadm It's not the system disk, but a raid 1 mirror that contains some files I really need to keep. After power cut, restarted and now ...
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64 views

raid10 “recovery aborted due to read error” drives being marked spare

I'm trying to recover my RAID10 array. All devices are plugged into a PCI controller that I've been using for a number of years now. I just replaced all of the drives in the system, as they all seemed ...
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1k views

How to make Intel fake RAID 0 volume appear on boot with Ubuntu 14.04 in a multi-boot environment?

I have a computer with a Gigabyte GA-Z97N-Gaming 5 mainboard, a 256 GB drive for booting and two 3 TB drives meant to use in a RAID 0 setup with both ext4 and NTFS partitions. We are planning running ...
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812 views

Understanding iostat with Linux software RAID

I'm trying to understand what I see in iostat, specifically the differences between the output for md and sd devices. I have a couple of quite large Centos Linux servers, each with E3-1230 CPU, 16 GB ...
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602 views

mdadm raid 5 missing partitions after reboot

I had a working raid 5 array that had a whole debian install on it (I set it up during a debian install). I'd been using it a couple of days, all was fine, but since I created it during debian install,...
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98 views

Change Initramfs script

I made RAID 0 by mdadm'ing partition located on dmraid VIA VT6421 and Western Digital hdd. Installed Ubuntu on that RAID. Now, when I boot, I get (initramfs) ash prompt. There, I have to write mdadm ...
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Change numbers in the Number column to be consecutive from 0 for an mdadm RAID array

I have a RAID 1 array: # mdadm --detail /dev/md0 /dev/md0: Version : 1.2 Creation Time : Thu Oct 18 21:52:43 2012 Raid Level : raid1 Array Size : 1048564 (1024.16 MiB 1073.73 MB) ...