A linux utility used to manage software RAID devices.

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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 ...
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soft raid6 recover second disk fault

I had a disk failure in a hosted system and had the failed drive replaced. During recovery, a disk error on a different drive occurred. when the original error occurred: md2 : active raid6 ...
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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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21 views

Reading /proc/mdstat

I just built my first raid5 yesterday (with 4 hds) and was reading about monitoring with /proc/mdstat. My understanding is an ideal dispaly with 4 drives should be [UUUU] however mine reads [UUU_]. ...
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94 views

Linux RAID 1: How to make a secondary HD boot?

I have the following RAID 1 on a Centos 6.5 server: # cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb1[3] 974713720 blocks super 1.0 [2/1] [_U] bitmap: 7/8 pages [28KB], ...
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20 views

Force server to use all resources for resync

I need to resync my RAID and noticed that it isn't a big consumer. I have booted my system with the Rescue CD and started the resync. Looking at top it seems that the processes doesn't take much ...
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101 views

mdadm - Remove disk from RAID0

So, I'd like to know, is is possible to do the following with mdadm: I start with RAID0 configuration on 2 disks: sda and sdb. I would like to add one more disk to array, sdc and move all data from ...
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86 views

Reassemble RAID 1 array from old system

I recently upgraded my OS from RHEL 5 to 6. To do so, I installed the new OS on new disks, and I want to mount the old disks. The old disks are listed as /dev/sdc and sdd in the new system, they were ...
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17 views

mdadm array is active but is not listed

I am running Ubuntu Server 12.04. I did apt-get upgrade and received a warning from mdadm. update-initramfs: Generating /boot/initrd.img-3.11.0-24-generic W: mdadm: the array /dev/md3 with UUID ...
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55 views

Reconstructing the disk order in RAID 6 with 7 disks

a little background to this question first: I am running a RAID-6 within a QNAP TS869L external RAID/NAS system. I started with 5 disks of 3 TB each back in the day, and later added another 2 disks of ...
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29 views

Raid1+0: create stripe over two /dev/mdx on partition or not?

Given that I haven't found a way to define how a Raid10 is created with mdadm, i went the Raid1+0 solution. How to display/define Mirror/Stripping pairs with mdadm mdadm --create /dev/md0 --level=1 ...
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31 views

Use old raid drive as boot device without data loss

There were two disks in sw-raid. There were /dev/md1 as swap, /dev/md2 as boot and a /dev/md3 with ext4. The sw-raid was disabled by stopping and removing mdadm and then zeroing the superblock on ...
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58 views

How to display/define Mirror/Stripping pairs with mdadm

I want to make a standard linux software Raid10 over 4 HDD. The server has 4HDDs, 2 pairs from different vendors in order to avoid batch problems. I want to have the mirror over two different ...
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50 views

S/W RAID6 and 4k sector format — slow resync

I'm looking for reason why Linux software RAID-6 re-sync is much slower than I expected. I have used 6 WDC WD40EFRX HDDs (with 4k physical sectors) to create RAID-6 array. $ sudo mdadm -v -C ...
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45 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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44 views

Redundancy: LVM+mdadm or LVM internal RAID

The task is to create LVM storage for virtual machine images. So LVM will be used in any case. There are two ways LVM providing redundancy: block mirroring lvcreate -m 1 --mirrorlog mirrored -n ...
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36 views

EC2 save mdadm RAID setup in an AMI [closed]

On EC2, most of the larger current generation instances have multiple SSD devices. To take advantage of the combined size of these for applications like nosql databases that store large amounts of ...
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899 views

mdadm Boot Error, incrementally starting raid array Ubuntu SErver 14.04

i build a small Server with Ubuntu 14.04 for Samba, I has one SSD Drive (the ubuntu installation is on it) and 2 3TB SATA Disk, the sata disk are combined to a Raid 1 with mdadm. Now sometimes (no ...
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73 views

System wont boot from degraded RAID6

I have a Debian Wheezy with 3 Partitions as RAID6. MD0 is for Root and OS, MD1 is for SWAP and MD2 for Files. While copy files to MD2 the system reports kernel panic and halts. I have had shutdown on ...
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47 views

How to add partition table to existing EXT4 filesystem

I have software RAID6 on 8x3TB disks (18TB), there is filesystem od device /dev/md1, but EXT4 can`t be bigger than 16TB so there is 2TB of free space. I would like to use this space. My first idea was ...
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Did mdadm --create destroy my data?

I think I messed up pretty bad. On my old system, I had 2 identical drive that were assembled with mdadm as a MD RAID 10 with a "far" layout. When building my new system and migrating the two disks, ...
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164 views

mdadm Stuck at rebuilding spare

I have the following Raid configuration, cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] md4 : active (auto-read-only) raid5 sda5[0] sdd5[4] sdc5[2] sdb5[1] 1536 blocks ...
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105 views

mdadm RAID-1 extremly slow on Debian Squeeze

Today I has started experiencing troubles with my php/web server. I've a lot of segfaults messages in php-fpm logs. At first I thought it was problems with versions incompatibility of may be some php ...
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115 views

Ubuntu 12.04 MD array not assembling after motherboard change [closed]

I recently upgraded my server by installing a new Xeon e3-1270v3 and Supermicro X10SAT board. Installation was simple and I reconnected my controller card, a LSI 9211-8i. When I booted the array would ...
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89 views

CentOS System Recovery : Overwritten RAID Superblock and porting to new hardware

I have a failed system running on CentOS 6 and would like to attempt recovery of system. One problem it has is the mdadm superblock appears to have some issues, it has all sorts of inconsistent ...
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34 views

Files missing after RAID1 restore

I have encountered unpleasant situation. Given mdadm RAID1 of 2 HDD on server. Yesterday one of HDDs completely dies, other shows bad SMART status but was in accessible state. Mdadm showed "clean, ...
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158 views

Optimizing disk performance on KVM VM configuration

I have a KVM host server running Ubuntu 12.04 LTS, bare bones installation with only KVM installed. The server has an 8 Core Intel(R) Xeon(R) CPU E3-1230 V2 @ 3.30GHz CPU with 32GB of RAM and SATA ...
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14 views

mdadm - diffference between metadata version

Can anyone tell the difference between all the metadata versions for mdadm? When I try the command mdadm --examine /dev/sda1, I can't seem to find preferred superblocks on version 1.2. Is there a ...
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50 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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87 views

Software RAID: file system becomes read-only, mdadm fails with SEGFAULT

I have software RAID1 on Ubuntu 10.10 (Linux ubuntu 2.6.35-32-generic-pae). It is dedicated server I control via SSH. Yesterday datacenter people changed one HDD which was crushed. I did not run ...
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72 views

mdadm RAID 1 config deleted

one of our huge production servers crashed this morning due to a HDD failure on port 0 (the bootable one). That server was running CentOS 6.5 in RAID 1 with mdadm. Although, a trainee changed the HDD ...
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381 views

CentOS 6.5 mdadm Raid 1 - Kernel Panic during raid data check

I have a brand new CentOS 6.5 install with two (mounted to /mnt/data) 1tb Western Digital Black drives in raid 1 with mdadm, configured via the installer. Unfortunately every now and again the entire ...
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129 views

SMART short offline test never ends for all drives of a RAID1

I'm having a strange situation here. After some three years in a low traffic server, one of two Samsung drives in a RAID1 has failed yesterday: Personalities : [raid1] md0 : active raid1 sdb1[2](F) ...
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93 views

DegradedArray event after rsync but later mdadm and smartctl do not show any issue

I have in my cron rsync active and I started to get emails after each rsync This is an automatically generated mail message from mdadm running on titan707 A DegradedArray event had been detected on ...
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103 views

Is mdadm RAID Toast?

I took all my drives out and put them onto a new cpu/mobo. (upgrading) I boot up and mdadm claims it can't boot my degraded RAID. /dev/sdb sudo mdadm --examine /dev/sdb /dev/sdb: ...
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45 views

2 disk RAID5 Linux software array

(I've posted this on Serverfault as I suspect it a bit to technical for Superuser. If I'm wrong please move it where appropriate) I am remotely looking at a device which identifies as ReadyNAS ...
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69 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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492 views

Linux; What is stripe_cache_size and what does it do?

I am currently building a software RAID under Linux using mdadm utility and I've read a few articles that describe how to increase the stripe_cache_size value for that RAID and how to calculate an ...
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1answer
114 views

Linux; Set RAID5 chunk size to 4kB to match FS block size and physical disk sector size

There are many discussions and websites that explain the process of setting up a Linux software RAID with mdadm with the chunk size of a new RAID as 128kBs or 512Kbs. Serverfault is no exception. I ...
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86 views

install mdadm without user input in wheezy

I am switching to debian from ubuntu and setting up RAID0 on my AWS boxes using user-data. Things were working fine on ubuntu but on wheezy apt-get -y install mdadm --no-install-recommends throws ...
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59 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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450 views

Very poor disk performance on KVM node - mdadm raid10

For a long period of time, i'm experiencing performance issues on CentOS servers that are used for KVM virtualization. I'm running software RAID-10 with 4 disks (Seagate ST2000DM001, 2TB, 7200rpm ...
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34 views

Growing a raid 1 with mdadm

I have a RHEL 6.5 box in which I have recently added two partitions to the a raid 1. It took the the disks without any incidents but I am not able to resize the raid itself. The output of cat ...
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74 views

confused by iostat reporting striped mdadm more tps than aggregate volumes

I've got an mdadm striped device (/dev/md0) from /dev/sdm{1..4}. Here is an output of iostat 30 and then mdadm --detail on the mdadm device # iostat 30 Linux 2.6.32-309-ec2 (ip-xx-xx-xx-xx) ...
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92 views

mdadm constant disk i/o

I have an mdadm array which has constant disk i/o. I know it's the array bc my server shows which specific drives have activity. According to iotop there's a constant disk write of 3-6 Mbps, however, ...
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704 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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92 views

mdadm array fails to start at boot, bad superblock on component drive

At boot my mdadm raid5 array fails to start, saying that one of my disks (sdi) has a bad superblock. However, once I log in, I can start the array no problem with mdadm --assemble /dev/md0 ...
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209 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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expanded 8 drive RAID 6 fails to assemble in new server, 5 original devices show no md superblock

I am in desperate need of you help. Neil Brown does fantastic work, and I have relied on mdadm for years to run very stable server systems, never had major problems I could not solve. This time its ...
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151 views

How do I fix my server to boot properly after removing / adding a drive on my mdadm software RAID

I configured a RAID-5 array for a data partition mounted on /mnt/data. My system is not booting on it (/ and /boot is on a dedicated drive not part of any RAID array). I added a 4th drive to my 3 ...