A linux utility used to manage software RAID devices.

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Q: MDADM mismatch_cnt > 0. Any way to identify which blocks are in disagreement?

Okay. After a routine scrub, my MDADM RAID5 is reporting mismatch_cnt = 16. As I understand, this means that while no device reported a read error, there are 16 blocks for which the data and parity ...
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8k 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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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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1k 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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741 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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68 views

mdadm - stuck reshape operation

I have a 3 disk RAID 5 array that I tried to add a 4th disk to. mdadm --add /dev/md6 /dev/sdb1 mdadm --grow --raid-devices=4 /dev/md6 This operation started successfully and proceeded until it hit ...
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24 views

Can I increase the read error threshold on Linux software raid?

I have a two RAID 10 volumes where only one partition on /dev/sda was kicked out of one of the two volumes. Here's /dev/mdstat (in the middle of recovery): md1 : active raid10 sda3[4] sdd3[3] ...
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89 views

Can't stop and reformat /dev/md0

I want to reformat /dev/md0, which is a RAID0 array consisting of 4 disks (sd[bcde]). However, when I tried to run the command mke2fs, I received the following error message: /dev/md0 is apparently ...
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62 views

Unexpected discrepancy between write and read performance using cryptsetup 1.4.3 and 1.6.6 on Debian Wheezy (7.9) and Debian Jessie (8.2)

I have been setting up a raid1 array and have set up an encrypted medium using cryptsetup with default options. The raid arrays are supposed to use 2 drives, but for the moment, I only have 1 drive in ...
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60 views

Recovering an RAID6 using ddrescue. mdadm: failed to add, invalid argument

I had 3 drives fail in a matter of a week on a RAID6. Luckily, one drive seemed to be mostly fine. I was able to run ddrescue and it copied all but one small area (couldn't read 14MB out of 3TB). ...
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26 views

mdadm raid1 back to single drive

I have a raid1 install of debian 7 with software mdadm on 2 disks. What I want here is to split this to 2 separate systems and be able to multiboot them. I guess while I have the system running ...
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188 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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595 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 [2/...
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236 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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234 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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189 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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366 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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451 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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193 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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28 views

Recovering a RAID5

Hoping somebody here can help, as I'm a bit stuck on what to try next. Essentially, I had a RAID5 of 4 disks in mdadm. One of the disks started failing, not enough to have mdadm eject it, but enough ...
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33 views

mdadm scaling beyond 6 disks w/ ssd's

It seems Linux mdadm produces less writes & iops as more disks are added to an array. For example, I have tested the following configurations, with the defaults aside from changing the I/O ...
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16 views

Does mdstat showing very different block sizes for identical drives indicate a failing drive?

One of my servers has a RAID1 array composed of two 240GB SSDs. It is managed/controlled via Linux, not via a hardware card. Recently, for no apparent reason, the array needed rebuilding. I rebooted ...
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136 views

Which are possible hierarchies for bcache, mdadm RAID and LVM?

Assuming I want to use bcache for caching, mdadm for RAID (1) and LVM for partitioning (and that I don't care that there might be performance drawbacks due to many levels of I/O and device management ...
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38 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 a device unrelated to the array and that has been already replaced, after every reboot the ...
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50 views

Best way to remove drives from MDADM raid array

I have a situation with a RAID array; I'm concerned that the drives in the array are going to fail soon, and given their age, I would rather replace them sooner than later. The problem I have, is ...
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63 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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1k 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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141 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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239 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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1k 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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78 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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603 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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367 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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291 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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94 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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100 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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287 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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1k 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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325 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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302 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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33 views

CentOS 7 - software raid md devices not available with new kernel

Some background. The servers I am working on currently are hosted at OVH whom uses a custom GRS kernel with some functionality I need disabled. Although they do give the option to install the native ...
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30 views

Why does 'fstrim /' destroy my mdadm RAID 1 array?

I've rented two physical servers. The servers are identical, except from the disks. server#1: 2 x SAMSUNG MZ7TE512HMHP-00000 SSD server#2: 2 x SAMSUNG MZ7LN512HMJP-00000 SSD When I run fstrim -v / ...
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16 views

Is it safe to disable write barriers for mdadm RAID?

When configuring RAID 1 or 10 with mdadm, is it safe to disable OS write barriers (with barrier=0 or nobarrier)? As there is no writeback cache memory on software RAID.
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30 views

Confusion on how to hotswap dm-x device in software raid

Below is the dump when I do lsblk cat /proc/mdstat lmsetup -ls. So sde is dying and I would like to replace it. What i'm confused is, in lsblk it shows sde is part of md3 (software raid). but when I ...
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48 views

RAID10 array lost after reboot | Amazon Linux

I carefully followed this procedure to setup RAID10 on Amazon Linux: https://mongodb-documentation.readthedocs.org/en/latest/ecosystem/tutorial/install-mongodb-on-amazon-ec2.html I also upgraded ...
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44 views

Having trouble mounting an mdadm array. Corrupted Filesytem?

I have a server that crashed and won't power on. I don't care about the server, but I'd like to recover the data attached to 2 external usb drives that were mirrored (raid 1) using mdadm. This system ...
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71 views

How to recover XenServer vm's from a mdadm raid 1 HDD

I have an older server, namely, Fujitsu Siemens Primergy TX 150 S6 on witch i have installed XenServer 6.5.0-90233c. On it i have multiple virtual machines of different sizes of witch i need to ...
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51 views

How to backup mdadm RAID superblock info?

I'm Looking for a simple command that will backup the mdadm superblocks on a RAID volume. A quick way to scan you system would be: mdadm --examine /dev/sd[a-z]* > raid-volumes.txt Now after ...
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116 views

“personality does not support diskops!” when trying to add a drive to a mdadm raid array

I have a linux (3.19) server which uses software raid (mdadm v3.2.5) and there is a raid0 device (/dev/md2) set up, which currently has only /dev/sdb3. I want to add the unused disk /dev/sda3 to this ...
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85 views

RAID 5 keeps failing after recovery

I have configured a raid 5 with 6x2TB devices with mdadm (I shrinked it from 9 devices to 6): /dev/md0: Version : 1.2 Creation Time : Mon Sep 23 17:54:25 2013 Raid Level : raid5 Array ...