A linux utility used to manage software RAID devices.

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“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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1answer
77 views

Dependency failed for mount after dist-upgrade

Last weekend, I ran an apt-get dist-upgrade on a home Debian 8.3 system, and was surprised to see that it entered emergency mode on the next boot. The server in question runs LVM on top of a mdadm ...
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15 views

create raid1 from existing lvm local volume

I have an existing LVM, with one physical drive (say /dev/sdb), and one volume group (say volgrp1), here I have three logical volumes (say lvSys, lvHome, lvSwap). Now I worry about my data and by a ...
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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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raid5 array reassembles as raid0

I found simmilar problem here: Missing mdadm raid5 array reassembles as raid0 after powerout, but mine is a bit different. Here too my raid5 reassembles as raid0, but i don't see any of my devices ...
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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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24 views

Is there a way to rebuild only part of a disk in an mdraid5 setup?

Last night I accidentally used dd to overwrite the first ~20GB of a drive in a RAID5 array. When I noticed, I repaired the array with $ mdadm --fail /dev/md127 /dev/sdb $ mdadm --remove /dev/md127 ...
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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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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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What happens if Host OS of MDADM md0 crashes

So I am debating getting software RAID. But I am trying to reduce the single point of failure problem. I don't think hardware raid is an option as I can't afford a high-end adapter, and I think I like ...
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993 views

mdadm: can't remove components in RAID 1

I have my /boot partition in a RAID 1 array using mdadm. This array has degraded a few times in the past, and every time I remove the physical drive, add a new one, bring the array being to normal, ...
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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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5k views

RAID resyncing automatically?

I rather randomly checked the status of my RAID arrays with cat/proc/mdstat and realized, that one of my arrays seems to be resyncing: md1 : active raid1 sdb7[1] sdc7[0] 238340224 blocks [2/2] ...
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33 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 ...
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1answer
24 views

What happens if my RAID fails while the swap is on it?

Today I removed swap from the system drive on my Debian. And created a swapfile on md0. So, I have a RAID1 array for data and a swapfile (the only swapfile). The system with boot partition is on ...
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19 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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I'd like to verify mdadm RAID1 is completely fine

Is there some mdadm --verify similar command, which would read all sectors of both disks in RAID1 to truly verify it's fine?
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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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Remove 1 disk from mdadm RAID 0 array

The server has a 7-disk RAID 0 array, and sdf is starting to die. Is there a way to remove sdf while keeping the array intact? # df -h Filesystem Size Used Avail Use% Mounted on /dev/md1 14T ...
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Why does mdadm believe my raid1 “has failed so using --add cannot work”?

TLDR: Trying to add a blank partition to a degraded RAID1 with mdadm 3.3.2 (Debian Jessie) fails, saying the (perfectly working!) array has "failed" and "--add cannot work". Is it telling me of a real ...
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127 views

Configuring a mdadm RAID-1 on SSD and HDD

I need to configure a RAID-1 on one SSD and one HDD. Both SSD and HDD has some preinstalled software, which I don't need so both can be fully wiped if that is any advantage. My research so far lead ...
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144 views

FIx RAID configuration after upgrade to Debian/Jessie with ICH9 chipset

I upgraded from Squeeze to Wheezy without problems. But after upgrading to Jessie the system cannot boot anymore (using LILO). LILO ERROR: Duplicated Volume ID O 24.1 Loading Linux ....(snip) BIOS ...
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MDADM RAID 0 Failure

Last night I noticed my system clock on my Ubuntu Server was 5 minutes fast so I ran an 'ntpdate pool.ntp.org' command and went to bed. This morning I noticed that SAMBA shares were not working. ...
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Can I create a software RAID 1 with one device

I have a single disk that I want to create a Mirror of, Lets call this disk sda I have just bought another identicle size disk, which we can call sdb. sda and sdb have one partition called sda1 and ...
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Replacing a disk to RAID5 failed

I removed a faulty disk from my RAID5 with mdadm --manage /dev/md0 -r /dev/sdd1 and replaced it with a new one. I tried to add it with mdadm --manage /dev/md0 -a /dev/sdd1 but it's only added as a ...
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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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1answer
347 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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How to speed up migration from Raid 5 to Raid 6 with mdadm?

Today I started the migration of my Raid 5 to Raid 6 by adding a new disk (going from 7 to 8 disks, all 3TB). Now the reshape is in progress: Personalities : [raid6] [raid5] [raid4] md0 : active ...
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Using mdadm --examine to write mdadm.conf

I'm trying to script the RAID setup for a (growing) number of identical servers. The advice I've seen for using mdadm suggests that once the RAID array has been created you can run mdadm --examine ...
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how to access data on RAID10 (consisting of 2 disks) using only 1 disk?

A long time ago I setup a RAID consisting of 2 disks. I wanted more than else safety/redundancy and indeed I think I wanted a RAID1. Now I have only access to one of those 2 disks and looking at it I ...
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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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How to check mdadm raids while running?

I'm starting to get a collection of computers at home and to support them I have my "server" linux box running a raid array. Its currently mdadm raid1, going to raid5 once I have more drives (and ...
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Difference between UUID from blkid and mdadm?

Can someone explain the difference between the UUID's reported by blkid and mdadm? On one of our CentOS systems, for example: [root@server ~]# blkid | grep /dev/md1 /dev/md1: ...
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935 views

How to map a sata device name to a physical sata interface for RAID systems

I have a system with 10 SATA ports, and another SATA as the boot disk. The 10 SATA ports make up 5 software RAID1 arrays. The RAID disks may be removed between boots, and swapped in with arbitrary ...
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4answers
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Reassemble mdadm-raid5

A friend of mine has a mdadm-raid5 with 9 disks which does not reassemble anymore. After having a look at the syslog I found that the disk sdi was kicked from the array: Jul 6 08:43:25 nasty ...
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1answer
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Rebuild linux raid array?

I'm going to be building a media server soon and I want to know how hard it would be to rebuild an array in the event of an ssd failure. Here's what I'm doing. I'm going to have a 128GB SSD boot drive ...
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1answer
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RAID mdadm virtual disk too small

sudo mdadm --build /dev/md0 --level=linear --raid-devices=3 /dev/loop0 /dev/sda1 /dev/sda2 After running the above command, /dev/md0 is smaller than /dev/loop0 + /dev/sda1 + /dev/sda2. Why is that ...
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How to safely replace a not-yet-failed disk in a Linux RAID5 array?

I have a software RAID5 array (Linux md) on 4 disks. I would like to replace one of the disks with a new one, without putting the array in a degraded state, and if possible, online. How would that ...
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Shrinking LVM physical volume on top of mdadm degraded RAID array, adding a spare and rebuilding it

I have a Debian Wheezy system with a couple of 500 GB HDDs in RAID-1 (mdadm mirror), on top of which sits LVM logical volumes with 5 partitions (boot, root, usr, var and tmp), total size of 47.15 GiB. ...
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1answer
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Is it sensible to use multiple LVM layers with mdraid

I'm building up a home server that will be used for a handful of different things. I'd really like to try a Btrfs raid 1 array for a large data store, but I'm using CentOS 7 (older kernel although ...
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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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1answer
210 views

mdadm raid filesystem differs from disk filesystem

I have created a raid 5 using mdadm on Debian. I used 2 new and 1 "old" disks. The old one had ext3 before. Using "parted -l" I noticed the raid has ext4 as filesystem but the old disk has ext3. I ...
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File transfer between SSD and RAID array uber-slow

It's really simple: this server has an SSD for the main drive, and a RAID array (mdadm) for storage. Intermittently, it has a problem writing to the array: the write speeds slow down to the point ...
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1answer
150 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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2answers
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New RAID array will not auto assemble, leads to boot problems

I had just asked this question where I was unable to boot after installing a new RAID1 Array. I was able to get to the terminal, but once I sorted that out I realized that my problem isn't so much an ...
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3answers
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mdadm refuses to add second identical disk to array

I have a RAID 1 array which is in a degraded state and want to add another drive to it. # mdadm --detail /dev/md1 /dev/md1: Version : 1.2 Creation Time : Fri Mar 21 17:23:00 2014 Raid ...
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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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1answer
375 views

Resize MDADM/Software RAID underlying partition and filesystem

I am running out of space on my root partition and would like to steal some from a different partition. The drives are 2x120GB with mdadm software RAID. I am using CentOS 6.5 64-bit. I used the centos ...
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1answer
145 views

Data Recovery from a 4-Disk NAS RAID 10

I know there are similar questions to this but none specific to RAID 10 extracted from a NAS, so any help is greatly appreciated. So, basically the NAS is kaput but the drives are ok. Following the ...
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Missing mdadm raid5 array reassembles as raid0 after powerout

I had RAID5 array of three disks with no spares. There was a power out, and on reboot, the array failed to come back up. In fact, it the /dev/md127 device disappeared entirely, and was replaced by an ...