A linux utility used to manage software RAID devices.

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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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467 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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243 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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182 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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165 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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49 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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175 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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990 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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207 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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140 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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91 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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709 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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40 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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93 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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136 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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1k 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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105 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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371 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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113 views

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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356 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 ...
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149 views

mdadm raid10 or nfs performance issues?

I have a fresh mdadm RAID10 device which is healthy, built from 4 x 7200rpm SATA 3 drives: # cat /proc/mdstat Personalities : [raid10] [raid1] md2 : active raid10 sdc3[5] sda3[4] sdb3[1] sdd3[3] ...
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82 views

Drawbacks with smaller fdisk partitions, mdadm RAID10, LVM and KVM?

I am setting up a new virtualized server with KVM and LVM. The KVM host and all guests will be installed on a SSD drive. Each guest will have access to a RAID10 array made of 4x3TB sata drives, used ...
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283 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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35 views

MDADM RAID5 Size

I currently have 9x1TB disks in RAID5, which to me is 8TB worth of storage. However, I am not getting that at all. This was after moving from RAID6 to RAID5 and performing the necessary commands to ...
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122 views

RAID-5 array being split on reboot (ubuntu)

I've set up a RAID-5 array on Ubuntu 13.04 (kernel 3.8.0-27-generic) using mdadm - v3.2.5 - 18th May 2012. It appears to work fine and be in high spirits: $ cat /proc/mdstat Personalities : ...
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30 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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246 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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230 views

MDADM Rebuilding

I'm currently rebuilding a RAID6 MDADM array from 5 devices to 9. cat /proc/mdstat: Personalities : [raid6] [raid5] [raid4] md0 : active raid6 sde1[0] sdg1[9](F) sdh1[8](F) sdi1[6](F) sdj1[7](F) ...
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893 views

Slow disk I/O in KVM with LVM and md raid5

I have been battling with a kvm setup under debian for two weeks now, specifically with guest I/O disk performance. The system: -Supermicro 1018d-73mtf (X10SL7-F motherboard) -16GB ECC/UB -Intel ...
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21 views

Harddrive check going-on?

I have a server that has suddenly become unusable (responds very slowly to requests). It seems to be related to some on-going RAID check. Here is what I get when I run cat /proc/mdstat : ...
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162 views

Recommended solution to join partitions (disks) into single partition [closed]

I have 4 hard disks (1 Tb each) on server. It's debian wheezy, amd64. Disks 2,3 and 4 are not partitioned yet. I have to join them into single partition, it must be single filesystem/mountpoint for ...
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86 views

Check health of RAID array

I have a server with RAID 1. Currently when I type in the following command: cat /proc/mdstat I get: Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] [faulty] ...
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227 views

Is it safe to snapshot an mdadm RAID with only xfs_freeze?

Is mdadm guaranteed (and trusted via experience) to be safe for taking snapshots with only an xfs_freeze? I have encountered vague warnings about mdadm still working in the background, thus making ...
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31 views

mdadm grow operation giving nonstop libata errors

Running Debian 7, mdadm 3.2.5. I issued a command to grow a 5 disk, 3 spare raid 5 array to an 8 disk, 0 spare raid 6 array: mdadm --grow /dev/md0 --level=6 --raid-devices=8 ...
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635 views

How to delete removed devices from a mdadm RAID1?

I had to replace two hard drives in my RAID1. After adding the two new partitions the old ones are still showing up as removed while the new ones are only added as spare. I've had no luck removing the ...
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221 views

How to get rid of a stubborn 'removed' device in mdadm

One of my server's drives failed and so I removed the failed drive from all three relevant arrays, had the drive swapped out, and then added the new drive to the arrays. Two of the arrays worked ...
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722 views

flashcache with mdadm and LVM

I am having trouble setting up flashcache on a system with LVM and mdadm, I suspect I am either just missing an obvious step or getting some mapping wrong and hoped someone could point me in the right ...
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169 views

Path of md device wrong after reboot

I have to set up a software raid (level1) on a Ubuntu server 12.04. It should serve files in the network via Samba. The server has the following disks: 250gb Sata hdd (Ubuntu is installed on that ...
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137 views

Linux: How to restore data from failed disk from software raid

I have a disk failure in software RAID (1) and marked a broken disk as fault (mdadm --manage /dev/md0 --fail /dev/sda1). Unfortunately I destroyed data on the second disk after that. Is it possible to ...
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381 views

linux raid 1: right after replacing and syncing one drive, the other disk fails - understanding what is going on with mdstat/mdadm

We have an old RAID 1 Linux server (Ubuntu Lucid 10.04), with four partitions. A few days ago /dev/sdb failed, and today we noticed /dev/sda had pre-failure ominous SMART signs (~4000 reallocated ...
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46 views

Software (md) raid does not reuse new drive

I have software raid6 array, which failed today. I've removed failed disk. Here is status: /dev/md0: Version : 1.2 Creation Time : Sun Nov 4 04:26:03 2012 Raid Level : raid6 ...
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118 views

Expanding raid 5 luks partition

I have just bought 2 new drives to my raid 5 array. I have successfully added them to the array and resynced. I now have a /dev/md4 drive that is 16 TB, but the crypt-luks partition md4p1 is still 12 ...
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78 views

Replace a slowly dying drive in Linux software raid5

I have the same problem as in Can I "atomically" swap a raid5 drive in Linux software raid? i.e. a Linux software raid with 3 RAID5 disks where one disk is showing smart errors but isn't ...
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690 views

Fedora, fsck fails at boot

I'm facing a problem in my server during the startup. This is my actual configuration: 320GB each. Raid1 -> /dev/md127. Working. /dev/sda /dev/sdc 1000GB each. Raid1 -> Use to be /dev/md126, ...
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81 views

What is the correct way to create new raid5 in Linux?

I added some new disks, and tried to create new array, using: mdadm --create /dev/md/2 --level=5 -x 0 --raid-devices=4/dev/sd{a,b,c,g}2 It creates the array, but after reboot - it's gone. What ...
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184 views

Convert Raid 1 to Raid 10 with no new disks

I just got a new remote root-access server with 2 1TB disks in a Raid 1 configuration, running Debian (squeeze). Before installing my stuff on it, I'd like to switch to Raid 10 if I can. All the ...
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230 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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mdadm raid5 recover double disk failure - with a twist (drive order)

Let me acknowledge first off that I have made mistakes, and that I have a backup for most but not all of the data on this RAID. I still have hope of recovering the rest of the data. I don't have the ...
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226 views

M1015 pass-through and hot-swap in Linux with md raid (IBM x3620)

I'm setting up a small, but hopefully durable server for a student community, and the hardware is an IBM x3620 M3 with a builtin M1015 RAID card. To make the setup future proof and avoid vendor ...
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929 views

RAID Recovery on a QNAP TS-869U-RP

I've had my trusty QNAP NAS (T869-RU) fail on me over night with (apparently) two of the eight disks in the RAID5 MDADM array from /proc/mdstat: [/etc] # cat /proc/mdstat Personalities : [linear] ...