A linux utility used to manage software RAID devices.

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Change Initramfs script

I made RAID 0 by mdadm'ing partition located on dmraid VIA VT6421 and Western Digital hdd. Installed Ubuntu on that RAID. Now, when I boot, I get (initramfs) ash prompt. There, I have to write mdadm ...
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22 views

mdadm : difference in metadata versions

Can anyone tell me the difference between the different 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. ...
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Gentoo XEN host + EFI + MDADM + IMSM RAID5

I have a workstation with a working Gentoo setup. It uses IMSM FakeRAID (level 5) with 4 disks. Booting done without bootloader using Linux kernel EFI STUB. System works fine. Now I need to setup XEN ...
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68 views

How to open multiple LUKS volumes with key entered in initramfs?

I have a Debian 7.4 (stable) based server configured to use an encrypted (RAID1 + LVM) root partition (/boot is un-encrypted regular partition) to which I installed dropbear SSH server so I can ...
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26 views

Transfer 2 drive raid0 / lvm2 system to new drive pair

I have a multi-boot, multi-drive system that I want to transfer onto 2 bigger drives. Currently pc has 2x1TB drives with Fedora 19 running, using RAID0 drive mirroring, with LVM2 on top of the md. I ...
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Two arrays have slightly different array size with same size disks/partitions, why?

I created a software RAID 5 array one year ago using mdadm v3.2.x which shipped from CentOS 6.3, after few months, I moved/assembled the array to/in Fedora 19 (now Fedora 20). It had three 3TB disks ...
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RAID5 Arrary disappeard with no HW or SW changes made

I have a R-Pi running XBMC (Linux CaribNAS 3.10.24 #2 PREEMPT Mon Dec 23 05:18:12 UTC 2013 armv6l GNU/Linux) with a 3 disk raid 5 array that has been working up till yesterday when is stopped running ...
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92 views

Proper way to setup RAID in linux

I have installed Debian 7.4 on a server, and through the installer I setup both RAID and LVM for the drive that the OS is installed on. However, now I want to add two 4TB drives in a RAID-1 array to ...
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22 views

Linux software-RAID and bootloader

How is it ensured that Linux software-RAID superblock(for example version 1.2) can be created at 4KiB from the beginning of the drive? According to manual of mdadm it is. I mean isn't there a hazard ...
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understanding the “chunk size” in context of RAID

Am I correct that chunk size in context of RAID is essentially the same thing as cluster in file-system context? In other words, chunk size is the smallest unit of data which can be written to a ...
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understanding Linux software-RAID superblock

According to mdadm manual, --zero-superblock option will overwrite the superblock with zeros. As I understand, superblock is a 256 byte block on HDD/SSD describing the RAID level used, name of the ...
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79 views

Grow LVM RAID10?

RHEL LVM has supported RAID4/5/6 as of 6.3 and RAID10 as of 6.4. It's well-known that mdadm won't let you --grow raid10, my question is whether this is a limitation of LVM RAID10 too? If it is ...
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44 views

mdadm large memory consumption [closed]

I am building a RAID 6 with mdadm (8 WD Red 3 Tb) on Ubuntu 13.10x64 server with ext4 filesystem. When I download torrent on the array, server RAM is filled for maximum cap (8 Gb) memory is free when ...
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172 views

Software RAID 10 + LVM on mixed drives, sector alignment?

I have 4 2.5" 7.2k drives lying about and I'd like to build some RAID arrays for a bit of VM storage on my KVM lab box. There are 2x 320GB drives and 2x 500GB drives. I'm looking to create a RAID 10 ...
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101 views

mdadm - RAID5 array size vs. actual disk size mismatch

I have 4x 3TB WD RED disks that are in mdadm RAID5, which should total an array size of 9TB usable space, however I only have 6TB. I have confirmed all disks are in the array, the only strange thing ...
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192 views

Linux md RAID: /dev/md0 vs. /dev/md/0

On newer systems /usr/share/mdadm/mkconf (the script that is used to generate /etc/mdadm/mdadm.conf) tends to use the device name /dev/md/0 instead of /dev/md0: new-system ~ # /usr/share/mdadm/mkconf ...
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Tuning a CentOS VM running on an MDRAID-based XenServer storage repository

I've run out of ideas for tuning disk write speeds on a handful of CentOS VMs running on a lab XenServer 6.2 host. Running under the free license (so vendor support not a concern), the lab host is a ...
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113 views

Why is my ext4 filesystem recognizable only on the machine it was formatted on?

Xubuntu liveCD 11.04 running on "bad machine" with mdadm RAID1 array with an unrecognizable ext4 filesystem: To rescue some files, I installed a new hard drive and formatted it to ext4. I copied ...
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79 views

Removing failed disk from raid 1

my server (Debian Wheezy) has a failed disk. I have sda and sdb and according to the support of my hoster, sdb needs a replacement. I send them this information with the mdstat: ...
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507 views

bit rot detection and correction with mdadm

I'm about to re-organise all my HDDs in my linux box nas and would like to use mdadm raid for data protection and its flexibility for reshaping the arrays. However, before I use mdadm for this I'd ...
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raid5 exchange 1 of 3 harddrives [duplicate]

I want to exchange a Harddrive which is in a pre-failing state, (some reallocated sectors) which is used in a raid5 array with 3 disks (software raid with mdadm). Is it possible to set a new ...
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169 views

md raid1 ext3 and 4k sectors slow with directory operations

I recently moved from a hardware RAID1 enclosure to using two eSATA drives with md. Everything seems to be working fine, except for the fact that directory traversals/listings sometimes crawl (on the ...
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1k views

New md array is auto-read-only and has resync=PENDING

I've created a new md array with the following command: mdadm --create /dev/md1 -l 1 -n 2 /dev/sd[ed]1 But now /proc/mdstat shows the array as "auto-read-only" with resync=PENDING: ~ # cat ...
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292 views

Gentoo/mdadm: Remove 1 disk from RAID 0 array

The server has a 7-disk RAID 0 array, and sdf is starting to die. Is there a way to remove sdf while keeping the array intact? # df -h Filesystem Size Used Avail Use% Mounted on /dev/md1 14T ...
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180 views

mdadm + lvm2: destroyed all superblocks accidentally

I accidentally overwrote all my RAID1 superblocks with garbage. I think this happened because I ALT-CTRL-DEL booted when the Ubuntu had put me in some kind of hard disk recovery mode. My display ...
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151 views

mdadm; previously working; after “failure”, cannot join array due to disk size

Abstract I had a functional Raid 5 array, I rebooted the box, and then mdadm couldn't re-assamble one part. Seeing that it was only one part, I thought it would be easy to just re-sync. But that ...
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722 views

recovery data from RAID and disk failure (Linux)

Some background A friend of mine was using in his office a NAS Buffalo-LS-WVL with two disks of 1TB each. It seems that the two disks were mounted as raid 1, but, as you will read, probably they have ...
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RAID 5 with 4 disks fails to operate with one failed disk?

I found a question about mdadm spare disks which almost answers my question, but it isn't clear to me what is happening. We have a RAID5 set up with 4 disks - and all are labeled in normal operation ...
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755 views

Monitor disk health using smartd (in smartmontools) on a high availability software RAID 1 server

I have a server with three identical SATA/600 3TB drives: /dev/sda, /dev/sdb, /dev/sdc. The drives are partitioned, using GPT with three partitions each: 1 MB: Reserved partition for boot loader 1 ...
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441 views

mdadm with overlaying lvm - remove a hard drive

This is a hypothetical question, I'm just evaluating in which way I should configure my hard drives for my home-server and for that I need to know this: Let's say I have a Raid5 configured with mdadm ...
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954 views

What does mdadm's “spare” number mean?

I created a mdadm-based RAID 5 from six hard drives using the following command: # mdadm --create /dev/md0 --level=5 --raid-devices=5 \ /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 \ ...
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217 views

Can I create a 2 TB RAID-1 array out of one 2 TB disk and two 1 TB disks while preserving 1 TB of data?

I currently have 1 TB of data on a RAID-1 mdadm array. This array consists of one 1 TB disk and a 1 TB partition on a 2 TB disk. I have now bought a second 1 TB disk, and I would like to use this to ...
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Reusing older raid discs

I have a software RAID5 array (Linux md) on 4 disks; the OS is OpenSUSE 12.3. Recently I replaced a disc with a larger one (fail disc, remove it, add new disc). The capacity of the array has not yet ...
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How to blacklist bad blocks from a MD-raid + dm-crypt + ext4?

I have a ext4 partition, on top of a dm-crypt, on top of a MD-RAID 10. One partition (/dev/sdc1) dropped out of the array with a ton of read errors. I ran the manufacturer provided diagnostic tool ...
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159 views

Can one use a md-type raid-0 as a drive for zfs pool

I want to play with ZFS at my CentOS. At the moment I have two 750Gb drives and two 400Gb spare drives that I could use. Of course the simplest solution would be to take all of them and use only 400Gb ...
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306 views

erased md0, md1 and can't recreate them

I previously had a working RAID 1 array. I think as a result of running grub-install /dev/sdb and grub-install /dev/sdc I somehow wiped my computer of md0 and md1. I need to set them up again. When ...
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190 views

How to boot after RAID failure (software RAID)?

Previously I had a software raid set up using (mdadm) of drives sda and sdb. sdb failed and the only way to reboot the system was by unplugging the second hard drive. Now I've added fresh sdb and sdc ...
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110 views

Raid5 Device Has Less Space Than Expected

I have 3 3TB drives, and have raid5ed them together. I would expect to get a resulting device around 6TB. The command I used: mdadm --create md0 --level=5 --raid-devices=3 /dev/sda1 /dev/sdb1 ...
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Using Grub2 to boot linux mdraid whole device RAID6

Linux mdraid supports device RAID (as opposed to partition RAID). The new superblock versions are also smart enough to not put the meta data right at the start of a disk. Does that mean it's possible ...
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1k views

No /etc/mdadm.conf in centos 6

I have installed centos 6 and setup a new RAID array with two disks. every thing is ok and I have partitioned the array but I don't see any /etc/mdadm.conf or /etc/mdadm/mdadm.conf files. I have ...
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164 views

missing files after reassemble of RAID-5

I had to open my file-server's housing today to replace a faulty fan. What I didn't see was that one of the sata-cables was not properly connected. The 1st thing I did after a reboot was a check of ...
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647 views

mdadm - Accidentally ran “mdadm --create” on an existing raid-1. The superblock is now corrupt and I am unable to recover data. Did I bork my data?

I have /dev/sdb1 and /dev/sdc2 that were previously setup into a RAID-1 with mdadm, but then I reinstalled and lost the old configuration. Out of idiocy, I ran sudo mdadm --create /dev/md0 --level=1 ...
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How to safely replace a not-yet-failed disk in a Linux RAID5 array?

I have a software RAID5 array (Linux md) on 4 disks. I would like to replace one of the disks with a new one, without putting the array in a degraded state, and if possible, online. How would that ...
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52 views

Can I put 2 disks into a raid-0 array without reformating the FS?

We have an existing /dev/sda disk, we are adding an identical /dev/sdb I want to place these two disks in a raid-0 array. Can I do that without reformating /dev/sda?
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lost superblock in md raid

Issue on Red Hat Linux 5. Due to some miscommunication two LUNs in our environment were enlarged from 1.2 TB to 1.7 TB. Now, after a reboot, mdadm does not find the superblocks to build the array ...
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3k views

How do I recover files from a single degraded mdadm raid1 drive? “not enough to start the array”

Given a single raid1 drive in degraded/rebuilding state, can it be force mounted? I'd like to recover all the files before undertaking the dangerous operation of pairing it and rebuilding. As far as ...
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Ubuntu: How do the md devices get assembled at bootup?

How do the md devices get assembled at bootup in Ubuntu? Is /etc/mdadm/mdadm.conf truly the relevant factor here? My mdadm.conf is sound and I checked that while I was in the rescue CD environment. ...
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Disable RAID auto detect at runtime

In Linux, I'm partitioning two disks for RAID1 with fdisk. The first disk partitioning succedes, but the second fail because the raid starts automatically and occupy also the second disk (why? it ...
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338 views

How does mdraid resync work?

I have two drives in a mirror (linux sw raid/mdadm); one drive somehow left the mirror in the past and its content is now several days old. At this moment, I'm using degraded mirror (with one drive ...
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747 views

Unable to rename a RAID device: stuck with /dev/md126

I had a fully working server. I booted with SystemRescueCD, without writing anything. I didn't even mounted a partition. Then rebooted the server. The server no longer boot correctly because some ...