A linux utility used to manage software RAID devices.

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54 views

Why is my HDD partition a character special device?

I have a bunch of old 1T disks with an mdadm array on them. They had been out of commission for awhile, but yesterday I slotted them into a server running an up to date Debian Jessie. Eventually I ...
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435 views

CentOS 7: GPT and software RAID 1 without 'biosboot' partition

I have a CentOS 6 server with software RAID1 (2x3TB): - sda # parted /dev/sda unit s print Model: ATA TOSHIBA DT01ACA3 (scsi) Disk /dev/sda: 5860533168s Sector size (logical/physical): 512B/4096B ...
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135 views

RAID1 disks “forked”, now duplicate

I have got a server hosted by OVH, which is configured to have a soft RAID1 array, /dev/md0, that holds a LVM PV. There is another /dev/md1 array, which was supposed to be the /boot, but which is ...
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4k views

How to recover an mdadm array on Synology NAS with drive in “E” state?

Synology has a customized version the md driver and mdadm toolsets that adds a 'DriveError' flag to the rdev->flags structure in the kernel. Net effect - if you are unfortunate enough to get a array ...
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531 views

mdadm error: found two disks with the number 0

Im running a server deep in the forest , and after a hard disco failure i got this error. error: found two disks with the number 0. It a server with 2, 1 TB disc in raid 1 with mdadm 0.9 SDA failed ...
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420 views

Restore LVM if VG is not consistent (XenServer 5.6.1)

i have a VG that uses the PVs /dev/md1 and /dev/md2. Now one hdd failed in /dev/md1: [root@xenserver1 ~]# cat /proc/mdstat Personalities : [raid1] md1 : active raid1 sda3[0] 382320128 blocks ...
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219 views

raid 5 mdadm drive dropped whilst growing

I have a 4x 2tb raid 5 mdadm array which I had begun to grow onto a 5th disk. ~# mdadm --add /dev/md1 /dev/sdb ~# mdadm --grow /dev/md1 --raid-devices=5 midway through the grow I recieved this in ...
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2k views

Calculating correct stripe size for Linux mdadm RAID10 arrays in “far” layout

I'm creating RAID10 array from 6 drives. When created in near layout, e.g. mdadm --create /dev/md2 --chunk=64 --level=10 --raid-devices=6 --layout=n2 /dev/sda1 ... Checking stripe size as ...
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346 views

MD Raid can't be assembled

I was running a Raid5 with 3 disks at on my homeserver. But had some problems with the back-plane for the disks. The disks weren't detected reliable. So I replaced the back plane and the disks are now ...
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440 views

How do I create a RAID10 array using EBS on Amazon?

Basing this question on information I got in Why does df shows only half the size of a RAID10 array?, how should I create a RAID10 array using EBS volumes on Amazon, in a way that will not be ...
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172 views

mdadm LBA mapping

I am trying to write a script similar to mdtrim (https://github.com/Cyberax/mdtrim) for a raid 0 software raid through mdadm. The mdtrim is for raid 1 only at the moment, and it works by writing a ...
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16 views

Can't see other VHDs after detaching another. Azure Ubuntu VM

We have encountered high Disk IO on our Ubuntu 14.04 VM's running mongoDB. On Windows Azure. To solve this issue we have changed the VM size from A2 to A3 (to add the additional data discs) and ...
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968 views

Ubuntu 14.04 mdadm issues on boot

I have a 14.04 Ubuntu machine which has: 2 x SSD in RAID 1 (md0) 3 x Sata HDD in RAID 5 (md1) The machine is set to boot from the md0 device. This machine has been running fine for a month or so, ...
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119 views

Upgrade Raid 1 to Raid 0+1 and bootloader issue

I am trying to convert my current RAID 1 to RAID0+1 and facing issue in installing bootloader - please have a look what i am doing. My current configuration is RAID1(2*10GB): [root@localhost ~]# ...
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151 views

shrink live mdadm partition with LVM

My goal is to shrink an mdadm RAID 1 partition while the system is running. I have to disks sda and sdb, which build my two RAID partitions md0 and md1. On md1 I use LVM, md0 is the /boot partition. I ...
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625 views

calculating optimal chunk size for Linux software-RAID

Am I correct that optimal chunk size is average file read/written to disk divided by number of block devices in RAID array storing the data? For example if the average file size is 1024KiB and I have ...
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611 views

grub on debian wheezy doesn't recognise mdraid

We're having a really strange problem when trying to boot from an mdraid on Debian Wheezy. All references online that I can find tell me that grub 1.99 (which is part of Debian Wheezy) should have no ...
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42 views

mdadm confused on minor number

Recently replaced a faulty disk in my Raid 6 group. All went as expected, no problem. After getting everything rebuilt using a new /dev/sdi1 as a replacement for the failing /dev/sde1 I decided to ...
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417 views

syncing mdadm event count

I had a disk die in my level 5 RAID and before I could replace it, my RAID crapped out while I was copying some data onto it. Reading the RAID kernel wiki on RAID recovery I've tried forcing an ...
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253 views

How to disable MD RAID or prevent degraded arrays from starting. (Centos 6.4)

I am trying to disable software RAID at boot time. My ultimate goal is to prevent the system from starting raid arrays that are in a degraded state. rd_NO_MD is present on the kernel command line by ...
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227 views

Resize a RAID 5 Partition

I'm moving my VG to a RAID, i have 3 disk 600GB, the VG is in the partition /dev/sdc2 /dev/sdc1 1G type linux <-- Boot partition /dev/sdc2 599G type Linux LVM One disk have the VG and with the ...
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90 views

Expanding raid5 software raid

I have recently bought 4 2TB drives to expand my existing 4*2TB raid5 setup, using mdadm software raid in debian. As a initial step, I have created a raid5 on the four new drives and created an ...
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94 views

Fresh debian squeeze software raid install wont boot

I am following these instructions: http://www.iprobot.net/linux-tutorial/how-to-setup-software-raid-in-debian-ubuntu/ (I used debian-live-6.0.6-amd64-gnome-desktop.iso and DD'd that onto a usb key, ...
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174 views

mdadm drive UUIDs chanaged, can they be changed back?

So I ran into this trouble and I believe I lost all my data..However I found an old mdadm --examine --scan file I made a month ago and an old mdadm.conf....Is it possible to use these two items to fix ...
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212 views

Raid1 disk degraded after reboot

I'm testing a Rackspace cloud server and have two Cloud Block Storage volumes set up in a Raid1 configuration. There are no system files on these volumes, they're purely for storage. Everything ...
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181 views

four-disk md raid10-far can be assembled and ran as “clean, degraded” with only 2 disks. Bug or i'm missing something?

Today i was solving raid failure on raid10-far with four disks. One disk failed and another wasn't re-added after a hard reboot. The mdadm -D was reporting it's clean and running with only two out of ...
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945 views

mdadm raid1, [1/2] disks failed, safe to reboot?

I am seeing the following under /proc/mdstat Personalities : [raid1] md1 : active raid1 sda2[0](F) sdb2[1] 976554876 blocks super 1.1 [2/1] [_U] bitmap: 4/8 pages [16KB], 65536KB chunk md0 : active ...
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302 views

After upgrade to SLES11 SP1 - LVM on top of software RAID5 not working anymore

On a system where I have been running OpenSuSE11.1 for some time I performed a fresh installation of SLES11 SP1. The system used a software RAID5 system on top of which an LVM was setup with a single ...
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268 views

Reassemble RAID 10 array without losing data

I have a RAID 10 array created from 4 iSCSI devices. This morning I temporarily lost connectivity to 2 of those drives. And it was long enough for mdadm to take them out of the array. Unfortunately ...
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25 views

Write cache settings not working

I am using Debian 8.0 x64 with 72 GB of RAM with 4 drives configured as software RAID 0. Linux s1 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1 (2015-05-24) x86_64 GNU/Linux I tried setting dirty ...
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16 views

mdadm and LVM high load and IOwait

I've got a new CentOS 6.6 server with 2 HDD with mdadm & LVM. As I've used the CentOS install CD I assume everything should be aligned properly. I've just written a KVM image to a LVM LV using dd ...
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50 views

Mount a NTFS Raid0 disk under linux debian

In my new laptop I have a a RAID 0 configuration with a normal disk and a smaller SSD drive. I have removed the dvd bay and replaced the dvd player with a 256 GB SSD drive where I run linux debian. I ...
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31 views

MD RAID Array Often Starts Without All Drives

I find that, when I start/restart my system, my MD array often doesn't start with all of the drives even though the device-names haven't changed at all. I'll have to stop the array and reassemble it, ...
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87 views

Ubuntu RAID1: How to boot after (physically) removing /dev/sda? (mdadm, Grub2)

Several months ago I installed Ubuntu 14.04.2 Server (x64) with RAID 1 using the following instructions: https://help.ubuntu.com/lts/serverguide/advanced-installation.html I followed the ...
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28 views

mdadm does not let me set --size manually, but grows to the same size later

I'm trying to make raid1 out of 2 disks the size of which differs a lot (ec2 provides iops based on disk size, so I want to have more iops, but don't care about losing some free space). However when ...
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49 views

Software Raid: Array inconsistent state

I'm running software raid 1 with md on debian distro. One of the disks has failed, but not all of the raid arrays were at that time in a "fail" state. In order to bring them also in a fail state (in ...
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102 views

mdadm: activating spare and removing 'removed' disks

I added 1 disk to my raid array, started reshaping, and then remembered that I forgot to partition the drive. So I partitioned and readded the disk. I'd like to get rid of that 'removed' and activate ...
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213 views

How to setup Debian Jessie to boot from broken RAID1

I want to setup Debian Jessie in EFI-mode with a LVM on an LUKS on a RAID1. I tried it with the Installer but when i remove one of the hard drives the whole system isn't booting any more. What I ...
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59 views

Data recovery seems impossible after kernel upgrade. MDADM (Raid1) LVM2

I opened a question about rebuilding a bad partition My Problem that din't take me anywhere. Bad news is the company trying to rescue the data says it's finding huge inconsistencies they can see some ...
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84 views

Can't rebuild a linux RAID array after replacing disk, “mdadm: Cannot open /dev/sdb1: Device or resource busy”

I have replaced a failed drive in my server with a new one, and wish to add it back to the array. I am getting the following error, what can I do to resolve this? [root@la ~]# cat /proc/mdstat ...
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27 views

Not sure how to change primary partition size and add a new partition on a software RAID1 using mdadm, as well as parted or fdisk?

I'm trying to create a /data partition to run drbd. However the drbd guide only shows steps for an fdisk on a normal disk, and not mdadm software raid. So I have sda3/sdb3, which are holding ...
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31 views

Transient errors on Linux RAID1 and RAID10

On the Arch Linux wiki you can read: Due to the fact that RAID1 and RAID10 writes in the kernel are unbuffered, an array can have non-0 mismatch counts even when the array is healthy. These non-0 ...
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93 views

mdadm/grub2/lvm boot failure if all drives are physically connected

Weird problem here. I've got a Debian 7 server (quad core, 32GB RAM) that runs a whole bunch of VMs. The main boot drive is a RAID 1, with an LVM volume group called System, which contains a bunch of ...
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29 views

Order of execution: First file system, then array vs. first array, then file system

Suppose I have two HDDs, same manufacturer, same model, same attributes (volume, speed, cache, ...). Both are equally partitioned. I want to have a level one array of two disks with one ext4 ...
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93 views

mdadm: can't remove broken drive from raid1

I have a ubuntu server Ubuntu 12.04.5 LTS (GNU/Linux 3.2.0-34-generic x86_64) that uses a software raid with 2 physical drives. Apparently, one drive is unresponsive, and I try to remove it from ...
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52 views

mdadm - unable to reconstruct the raid1

When restarting my server, it (sometimes) fails to reconstruct my RAID-1 array (2 disks). My server, a 10-year-old computer, often changes sda into sdb or sdc which seems to annoy mdadm. When it ...
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94 views

Resizing a software RAID remotely, no LVM, / partition

I have a server that has a software RAID without LVM. That is only mdadm. There are the partitions /dev/sda2 and /dev/sdb2 which form /dev/md2. There is also a lot of space after both /dev/sda2 and ...
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460 views

mdadm RAID0 array recovery

I have a Linux file server with two 12-disk MD1000 disk arrays attached to a RAID controller. Unfortunately, a power blip has caused a loss of configuration data on the RAID controller and it is now ...
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86 views

mdadm reattached a failed drive all by itself

I have 2 drives setup in mdadm mirroring (3 partitions on each drive). Last week the second drive (sdb) dropped out of the array because of some I/O errors I am still investigating. After a server ...
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308 views

mdadm: All RAID disks look good, but can't access devices

Now, granted, issues with RAID rarely come up (at least with the one that I have to deal with in my life), so I'm not the most experienced person in the world. However, I'm not seeing any issues with ...