Questions tagged [mdadm]

A linux utility used to manage software RAID devices.

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State of LVM raid compared to mdadm

LVM and mdadm / dmraid are both offering software RAID functionality on Linux. This is pretty much a follow-up post to this question from 2014. Back then, @derobert recommends to prefer mdadm over LVM ...
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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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1answer
777 views

RAIDs disappearing on reboot (Centos 7.5)

I'm trying to create 4 RAID 0 disk arrays on my system running Centos 7.5 and have the RAIDs automount after a reboot. For some reason, only one of the RAIDs /dev/md0 is persistent between boots. The ...
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Hybrid RAID (SDD+HDD) gives unexpected results

I am doing some experiments with hybrid RAID in Linux. My test consists of the following: 2x256GB SSD in RAID 0 (/dev/md1) 2x256GB HDD in RAID 0 (/dev/md2) Then I made md1 and md2 into a RAID 1 (/...
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1answer
932 views

How to check/fix nvme health?

I'm running debian stable with a 2 x nvme Raid 1. Here is the hardware/hoster it's running on https://www.hetzner.com/dedicated-rootserver/ex62-nvme?country=us Almost every second day mdadm monitoring ...
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277 views

mdadm - are there any downsides of mixing 512 B and 4 kB logical sector size disks in RAID 1 or RAID 5/6?

I have a mdadm RAID 1 and RAID 6 setup with 8 TB disks which are using 4 kB physical sector size but 512 B logical sector size. I want to add more 8 TB disks to these arrays and the way I usually do ...
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56 views

update-grub/os-loader doesn't see multiple Ubuntu installations on software Raid

I have two disks containing multiple software RAID1 (mdadm) partitions . I installed Ubuntu 14.04 on /dev/md0 and /dev/md2 (corresponding to /boot and /, respectively) and Ubuntu 16.04 on /dev/md1 and ...
3
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1answer
443 views

On boot, automatically assemble mdadm array that uses another mdadm array

I have two mdadm arrays on my system: alex@fileserver:~$ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md1 : active raid5 sdc1[0] md0[3] sde1[...
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727 views

Understanding Linux software RAID, which devices are connected to my mdadm RAID 1?

I have a RAID 1 which was managed by Intel Rapid Storage Technology drivers. Im migrating this system to Fedora Linux and I ran mdadm --assemble --scan and it seemed like there was an array available ...
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220 views

Don't Spin Up Entire RAID for Read Access

I have a RAID 1 managed by mdadm consisting of a thumb drive and an external HDD. I set a spin-down time for the external HDD. If I access the file system of the RAID to read but not to write (for ...
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How can I completely remove software raid?

I have an install of CentOS 6.5 which was setup with software raid (as outlined in this official documentation). There are 3 hard drives and I have RAID1 running: NAME MAJ:MIN RM SIZE RO TYPE ...
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1answer
589 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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246 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 ...
3
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1answer
100 views

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 ...
3
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1answer
426 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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1k 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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Mdadm Raid6 Re(assemble|build|create) from 6x disk images of original array

I have 6 1TB drives from several years ago. There was a problem with the Seagate drives's microcode, so I updated it. Unfortunately, this reset the UUID of two drives and the RAID6 array was broken....
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76 views

How to recover journal superblock on mdadm RAID5 array

Yesterday my raid5 array with 3 disks was suddenly unmounted. After examining it, it seemed it had become degraded and one of the disks had a much lower event count than the rest. I started running: ...
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Why do my software RAID1 superblocks keep getting corrupted and how can I prevent this?

How might I be repeatedly corrupting my superblocks on RAID1 I have had two occasions in the past six months of RAID1 root arrays becoming unusable because of problems with the superblock. ...
2
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1answer
80 views

LVM Shrink to remove a device

I have Centos 7 I have a 7 drive RAID6 Array created using mdadm. (This is composed on WD 4TB Red drives) I have setup the RAID array as a LVM PV - all this has been working well for ages. I have ...
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1answer
208 views

mdadm external bitmap not used

I've place the bitmap on an external EXT4 drive (1xHDD) but I would expect the file to be written too whenever data is changed on my RAID10 array, right? I even did checksum of the bitmap file, and it'...
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167 views

Reducing disks from a RAID5 mdadm with LVM

Checking a system, I found a server with 12 4TB drives in Raid5, with LVM on top. Single VG, single PV, and a few LGs that wouldn't need more than 6TB of space (currently only 4TB). Read speed is no ...
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Can I enlarge a RAID partition?

I have an OpenSUSE 42.3 system with a RAID5 (mdadm) made out of four discs (2 2TB and 2 3TB). I'm growing the RAID by replacing the 2TB discs with larger ones. The 3TB discs have only 2TB partitions ...
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1answer
368 views

What is the best way to explain this LVM output?

I bumped into the issue two days ago about RAID issue on my TS-251+ QNAP. I do not really bother the box until the problem comes. I explored details to find out what type of RAID, how RAID/LVM ...
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1answer
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“rcu_sched detected stalls on CPUs/tasks” - jiffies - ESXi Ubuntu 16 FileServer Guest

I have a VERY simple Ubuntu 16 x64 VM setup on my ESXi host which acts as a fileserver. It has NFS/SMB and MDADM installed. It is fully updated. Twice in the last week it has hung with an error ...
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1answer
406 views

Is it possible to pause mdadm reshape while growing raid?

I'm using mdadm and I'm running a grow operation on my 3 drive Raid 5 to make it use 4 drives. I put the backupfile in /root/md0_grow.bak. The reshape is apparently supposed to take 7.5h hours, ...
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Can't restart a RAID6 array; missing personalities?

I have an 8-disk 32TB RAID6 mdadm software RAID array. I started the computer today and it won't start the array. It has the common symptom of marking the array inactive and all 8 drives as spares. ...
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933 views

Recovering partition from a linux RAID 1 array

I had an old server (Fedora 4-- yes, old!) die recently. It was configured with two IDE disks in a software RAID 1 array, and I'm trying to recover the data. Unfortunately it had been a while since I ...
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2k 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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585 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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1answer
1k 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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394 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 run ...
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1answer
275 views

Recovering a (not yet created) RAID5 with URE (Unrecoverable read errors)

I wan't to create a RAID5 array at home, the OS is Linux (Kernel 3.15.7) and the array will be created with mdadm. I wan't to create the array with eigth or ten 1TB discs. Let's assume a single drive ...
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1answer
2k 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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394 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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654 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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2k views

Hard drives goes missing until reboot - what can be the cause?

I am struggling here. My end goal is assembling a RAID-6 array on my PC, but time and again, the assemble doesn't complete (and cat /proc/mdstat shows that one drive dropped away). This now happened ...
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2answers
357 views

centos 7 mdadm raid 1 error,

I am trying to get RAID 1 using mdadm. But I got the following error. [root@localhost ahmed]# mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/sd[a-b]1 mdadm: /dev/sda1 appears to contain ...
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1answer
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How to track the start and end time of a raid5 rebuild?

This is my first post on the forum, so bear with me. I am new to the linux environment and also new to raid configurations. I am doing a work project where for part of this project I am measuring ...
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mdadm: How to create RAID50 on Ubuntu 16.04

I am unable to create a RAID50 with mdadm on Ubuntu 16.04. Every time I reboot the server, the RAID0 will disappear. Here is how we proceeded to create the RAID50 : Create two RAID5 (8 disks each) : ...
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Slow write speed on encrypted drive, while benchmark shows much higher encryption / raw disk write rates

I currently setup a NAS with Ubuntu 18.04 on a Netgear ReadyNAS 102device. The machine has a Armada Marvell 370/XP SoC with a hardware encryption accelerator called "CESA". The kernel drivers for CESA ...
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How create RAID 1 on working Slackware 14.2?

I use Slackware 14.2 (with kernel 4.4.14-smp) on sda and I'm trying to create the RAID 1 with additional sdb. I'm using the VM VirtualBox. First, I have cleaned the sdb: dd if=/dev/zero of=/dev/sdb ...
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1answer
96 views

can not shrink raid1 size with mdadm

I want to reduce a soft raid1 disk size, but the following cmd shows an error, root@GalensSynology:~# mdadm --grow /dev/md2 --size=83886080 mdadm: Can't read enough disk from md2 mdadm: component ...
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Recreating a RAID4 / RAID0 array

At first, there was a RAID0 array, to which I've added a new disk by issuing mdadm --add but when I've done that, the drive started to fail because of the power issues and the array has not started ...
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Disk utilization on mdadm raid 5 is 100% even though none of the member disks is at 100%

I am currently confused about the disk utilisation of one of my machines. The setup: I have a machine containing 4 2TB HDDs. For those HDDs I used mdadm to configure a RAID 5 (called md2) On MD2, I ...
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1answer
1k views

SW RAID-1 grub-install

I just changed /sda system disk in SW RAID using following steps, simply put: sfdisk -d /dev/sdb | sfdisk /dev/sda mdadm --manage /dev/md0 --add /dev/sda2 Now disk is initializing chcked by: cat /...
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323 views

Coping with bad sectors on RAID disk

I have a RAID 1 of 2 hard drives managed with mdadm. Today, one of them failed. I figured out that this is because of bad sectors in /dev/sdb. According to badblocks, these sectors are affected: 1028, ...
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498 views

recover data from former RAID 1 drive

I had a RAID1 setup (md0), mirroring two 2TB drives (sdb, sdc). When trying to remove the RAID to use the disks individually with the data on them, I ran mdadm --stop /dev/md0 mdadm --zero-superblock ...
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Unable to assemble existing RAID array with mdadm

I originally set up a RAID1 array on Windows with RST (not as a bootable disk). I recently started moving everything to xubuntu, so I tried mdadm on my xubuntu partition (dual boot). Installing and ...
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102 views

(Complicated) RAID hard drive issue

I have a (complicated) RAID hard drive issue: I have a Synology DS413j with 4 hds, hd 3 failed so I decided to replace them. The official support article says to replace them one by one, and being ...