Questions tagged [mdadm]

A linux utility used to manage software RAID devices.

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Re-assembling mdadm RAID1

I was in the process of reinstalling from Mint 18 -> 20. I have 2x 4TB devices RAID1'ed with mdadm. One of them had degraded/dropped off the array for some reason. (Not sure if this happens for any ...
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Linux software raid1: What reasons might cause a read speed reduction?

Configuring two PCIe NVME ssds as a raid1 linux software raid instead of boosting read performance has roughly halfed the read speed. In similar linux software raid1 setups (also ssds) I have seen an ...
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mdadm 4 drive RAID6 after booting older version (12.04 vs 14.04) with 3 drv all show up as spares

So I just need to get the array back, assemble with --force does not work cause it see's three spares and can't do anything with spares. I just have to find how to tell mdadm to unspare the 3 drives ...
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blkdiscard hangs on md raid 10 on PCIe SSDs

I have a running Linux 4.19 amd64 system with two PCIe SSDs that I'd like to clear, test, reformat and put in use again. All of the data has already been moved away. I've tried to trim/discard blocks ...
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mdadm RAID - Reboot during grow - reshape is not resuming

I am on Debian 10, a fresh install from a week ago. I moved my array from a previous server, everything went fine. I then added a new drive in the array and did a grow. mdadm --add /dev/md1 /dev/sda2 ...
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GPT error? /dev/sd*3 disappeared

This is related with this but simplify the problem. I have drive ~#mdadm --examine /dev/sdj /dev/sdj: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : a9bcec2a:...
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Raid 5 suddenly missing two hdd at the same time

I made a raid 5 with 4 drives /dev/sdh3 /dev/sdi3 /dev/sdj3 /dev/sdk3 Normally I started raid with this command mdadm --assemble /dev/md128 /dev/sdh3 /dev/sdi3 /dev/sdj3 /dev/sdk3 Suddenly something ...
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How to fix a bad checksum error on mdadm raid5 array (Ubuntu)

I have a 4 x 4 TB drive configured in a raid5 array. Drives labeled as /dev/sdb1, /dev/sdc1, /dev/sdd1 & /dev/sde1 assembled as /dev/md0 mdadm assemble output When I tried to assemble the array I ...
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How to install bootloader on Linux Mint 20 RAID0 on laptop?

I have created raid0 from two disks in ext4 using mdadm from livecd but ubiquity installer failed on grub-install hence I'm using ubiquity -b command in terminal. How to properly install boot loader ...
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mdadm problem on btrfs disks

Ubuntu 20.04.1, new reinstall. I accidently tried to mount my BTRFS raid 1 disks using MDADM. I now cannot mount my btrfs raid. $ lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT NAME ...
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Why does mdraid resync after a grow operation?

I recently decided to expand a NAS that's configured with mdadm raid1 volumes. Because disk slots are limited, the procedure for this is roughly: pull one of the disks and replace it with a larger ...
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Single RAID5 disk recovery Ubuntu 20.04

I have a Ubuntu 20.04 server, happily running 2 RAID1 arrays. I have a load of old disks that I want to check before deciding whether to backup before destroying. I am connecting the disk to the ...
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mdadm raid configuration from USB and best practice

I never configured mdadm before and I have a question. I have got two discs /sda and /sdb. Currently on disc /sda I have got debian system with sda1,sda2,sda3. Is it possible to run my debian and ...
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Optimal way to create mdadm raid 1 on USB adapter and then put it into slot on motherboard

I'm looking for the optimal way how to perform the task. On one of my debian servers: I have 2xSSD connected via USB adapter (no free ports on motherboard) I need to create RAID 1 MDADM array (2USB ...
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What's the mdadm --incremental function?

I can understand this command: mdadm --create --verbose /dev/md0 --level=1 /dev/sda1 /dev/sdb2 but I don't know what the purpose to do this: mdadm --incremental /dev/sdb
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mdadm does not persist RAID when re-booting

I have created a RAID-0 with the following command: mdadm --create --verbose /dev/md0 --level=0 --raid-devices=2 /dev/disk/by-id/ata-Samsung_SSD_750_EVO_500GB_ABC /dev/disk/by-id/ata-...
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Can I re-assemble my RAID 5 on only 2 drives using mdadm to recover my data?

I have a 3 drives RAID 5 on a CentOS NAS but 1 drive died. Since then, CentOS boot in emergency mode and I can't manage to get access to my data. I tried mdadm --assemble --scan and command returns ...
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bare metal raid array with LVM dissapears after reboot

tl;dr: RAID array + LVM dissapears after reboot. Detail I wanted to set up an encrypted raid array, based on this SO. I set up a RAID array "bare metal" (i.e. on the disks not on the ...
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Disable caching of mdadm's write-intent-bitmap?

TL;DR > How can any caching of the a raid1's write-intent-bitmap be disabled, to prevent the on-disk-bitmap not to be outdated in any situation? (Or is there a way to flush the cache bitmap to on ...
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How to setup mdadm raid1 auto-assembly, where external bitmap is itself on another mdadm raid1?

How can the assembling of a raid (as via information stored in mdadm.conf) succeed, given that its assembling requires a bitmap file, which itself is only available after another device has become ...
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MDADM and lib-virt KVM. After restarting KVM host, RAID devices disappear, and cannot be re-assembled

I have managed to establish that restarting my hypervisor somehow causes the raid setup on the virtual host to break. Here's what I did created multiple RAID 1 devices on the virtual host I can ...
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mdadm - Is it mandatory to run `update-initramfs -u` after raid creation?

I had some very strange experience with some raid 1 arrays recently, I've only just figured out vaguely what happened. I created 3 pairs of raid 1 arrays. Going back through the terminal history, I ...
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Can I decide which drives will be removed when reducing number of drives in RAID6 array?

I have a RAID 6 array of 7 drives, 4 TB each. I am replacing them one by one with 8 TB drives. I know how to grow my array when all of the drives are replaced. The larger drives have 8 TB partitions, ...
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Is it possible to split a single Raid 1 array pair and mount a single disk?

I'm having a lot of problems with raid 1 arrays on my server. Is it possible to split a raid 1 array into two seperate disks, and mount one, or either of them, as regular disks. The raid 1 devices ...
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MDADM RAID1 Creation - Which device is “master”?

In a RAID 1 config with MDADM, which device is the master device during the initialization process? In a RAID 1 config with 2 devices, presumably (?) one device acts as a master and the other as a ...
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MDADM RAID1 creation - What does the initilzation process do?

I am creating a RAID 1 mirror pair with MDADM. After creation of the array sudo mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb the array enters an initialization ...
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Two disks MD RAID 1 setup running with one disk

I have MD RAID 1 with two disks but one failed and will be replaced soon but till this time is it possible to set the raid to active to access my files because now the state is inactive ? Thank you. ...
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177 views

Can't run fsck or format device - device is in use

today I crashed my boot partition. While is normally no problem due backups, I can't write to the partition anymore. root@hades ~ # touch /boot/a touch: cannot touch '/boot/a': Structure needs ...
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Replace 500GB raid1 with 120GB raid1 with mdadm

I have a home server with two mirrored (soft raid1 with mdadm) 500GB HDD that contain the operating system. I would like to replace both the drives with two 120GB SSD mirrored in raid1 the same way. ...
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Is it possible to share the same Windows installation on two systems, a VM(Qemu/Libvirt) and the host. One using Legacy BIOS and the other UEFI

I want to use a single Windows installation on a VM(Qemu + Libvirt) and on my host. My VM can only use Legacy BIOS boot mode, because I'm passing through my Intel iGPU, which is currently only ...
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When should assemble be run?

Let's say we have a soft RAID1 with mdadm When should these command should be run? mdadm --assemble --scan Is there some risk in running twice?
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Raid5 mdadm array change size

I have created a raid5 array with 4 disks. Initially i had 3x 3tb and 1x 4tb (because 3tb was unavailable at the time). After some years i have replaced most of these disks and have come to the point ...
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Debian mdadm RAID - rebuild and level modification

I would like to build a new NAS and run Debian on it to make the files available with Samba. I would like to use RAID5 and RAID6. I read that mdadm is the right tool for this and how you can set it up....
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Attempted to replicate partition table to replacement RAID1 disk, but source partition table now empty

I had a disk (/dev/sda) show signs of eventual failure in a RAID1 array, so I failed and then removed it from the array. I then replaced the disk, booted back up, and began the process of replicating ...
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Recovering failed RAID5

md0 : active raid5 sdc2[5](S) sda2[4] sdd2[3](F) sdb2[1] 17510688768 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/2] [UU__] What happend: sdc failed I have repleaced it with a new HDD ...
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RAID1 no suitable drives found

I have a synology NAS with 2 disks configured in RAID1. Somehow the RAID array got messed up. I plugged the 2 disks into my desktop computer to investigate what's happening: # mdadm --examine /dev/...
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Quickly assemble raid5 for perf test

I'd like to run a series of fio-based performance tests on a few drives in various RAID and non-RAID configurations. When assembling drives in RAID5, the rebuild process takes an incredibly long time (...
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164 views

mdadm not enough to start array - /dev/sdc2 no superblock

After a power failure on a server with 4 disks in RAID6 configuration, /dev/md1 won't come up (though /dev/md0 does). mdadm --assemble --scan mdadm: /dev/md/1 assembled from 3 drives - not enough to ...
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Newly created mdadm raid 6 cannot be mounted

I have a newly created mdadm raid 6 that was built using this command: sudo mdadm --create --verbose /dev/md127 --level=6 --raid-devices=8 /dev/sdi1 /dev/sdj1 /dev/sdk1 /dev/sdl1 /dev/sdm1 /dev/sdn1 /...
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581 views

RESOLVED: EXT4-fs (md1): unable to read superblock - really want to avoid data loss

my level of Linux knowledge is very light (I'm learning) and I've got a problem that's beyond my level of Google-Fu. I'm well out of my depth and I'm hoping somebody might be able to help me... I'm ...
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How do I reassemble mdadm array with both drives available?

I need to re-instate an RAID 1 (mirror) array. I have both drives and mdadm tells me the following about them: $ sudo mdadm --examine /dev/sdb1 [sudo] password for pi: /dev/sdb1: Magic : ...
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mdadm RAID array gone after reshape and reboot

My mdadm RAID5 array just underwent a 5>8 disk grow and reshape. This took several days and went uninterrupted. When cat /proc/mdstat said it was complete I rebooted the system and now the array no ...
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Starting RAID array manually

Is there any way to start a RAID array manually without rebooting after stopping it via mdadm -S?
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Restore Hardware RAID5 using 'mdadm'

I have a Hydra LCM RAID device with 4 Bays (4x 2TB Hitachi). I was running it in RAID5 mode since 2010. Last year in May the device was starting giving messages that one drive was degraded and I ...
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76 views

Setup RAID10 (mdadm and/or lvm) starting with three empty disks, then add fourth disk (has data in it)

Please, tell me if it is possibile to create RAID10 (near layout) with odd drives and then adding even(th) disk to that existing RAID10. TOTAL: 4* 2TB drives (sdc,sdd,sde,sdf) FREE: 3 of them (sdd,...
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Creating RAID arrays on files instead of block devices

Is it possible to create a RAID array on files for testing purposes? Suppose I want to create a level-1 RAID and I don't have for example 10 block devices to do that but instead I want to simulate ...
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116 views

mdadm raid issues with (possibly out of date) and tries to mount raid6 as raid1

Some unknown hardware issue occurred that looks like it took all 4 hard drives offline occurred. wiggled some wires and hard drives are back (???). Now having raid issues. Raid will not start "/...
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1k views

mdadm - how to rebuild raid array after fresh install?

I used to have a raid1 array on the mountpoint /mnt/md0, however I re-installed my OS and now I don't know how to re assemble it. I believe I should be doing something along the lines of mdadm --...
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252 views

Linux I/O Deadlock since Kernel Upgrade

I have been using Linux-Kernel 5.4.35 (and newer versions) after upgrading from 4.19, and ever since that my hpsa md RAID 0 hangs after some days (2-3 Days), RAID changes to read-only/I/O rejected. (...
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Cloning a mdadm RAID1

I have an old PC which has two internal hard drives of 80GB in a mdadm RAID1 configuration with LVM on top of it. I wanted to migrate this PC to a virtual machine, so I booted both, the PC and the VM, ...

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