A linux utility used to manage software RAID devices.

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Drop in write performance when mirroring two RAID 0 arrays

On a CentOS 7 server with 4 SSDs, I created two RAID 0 arrays with mdadm. Both were formatted with ext4 and mounted on separate directories. I benchmarked them using fio and got the following results ...
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How to create imsm metadata raid1 using mdadm and skip initialisation

I am trying to use --assume-clean option to speed up raid1 creation, using these commands: mdadm --create /dev/md/imsm /dev/sd[c-d] --raid-devices 2 --metadata=imsm --assume-clean mdadm --create ...
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mdadm raid 1 ssd (ata1.00: failed command: READ FPDMA QUEUED - ata1: hard resetting link)

system: Centos 6.7 2.6.32-573.12.1.el6.x86_64 motherboard ASUS P6X58D-E Two ssd: hdparm -I /dev/sda /dev/sda: ATA device, with non-removable media Model Number: TS128GSSD340K ...
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25 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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mdadm --grow power failure, /dev/md2 no longer detected, RAID5

Did a terrible stupid mistake. Please advise me how should I best proceed. My configuration is a RAID5 of 4x4TB drives. On top of it, LVM with various partitions including /, swap, everything. The ...
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RAID not changing write speeds [migrated]

So I have two hard drives one connect with SATA and one with USB3.0 SATA (/dev/sdc1): Apple HDD Toshiba USB (/dev/sde2): Western Digital Technologies, Inc. Elements SE Portable ...
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GPT, grub and mdadm. sda drive replaced, raid rebuilt in recovery mode, but now server won't boot

This is how partition table loooks like: (parted) print Model: ATA TOSHIBA DT01ACA2 (scsi) Disk /dev/sda: 2000GB Sector size ...
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78 views

SSD DD write speed lower than HDD [closed]

I've come across a strange phenomena with a new dedicated server that's been provisioned. The server has 2x1TB HDDs in software RAID 1 and a separate 120GB SSD that is intended to be used as a ...
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27 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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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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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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18 views

Server rollbacked after apt-get upgrade and a restart

Today I was trying to find out why my server stalled after certain amount of requests on apache2, but couldn't figure why, so I decided to upgrade it(apt-get update & apt-get upgrade) before I ...
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14 views

How to keep md-raid from blocking IO?

I run a server with md-raid (software) level 1 (2 HDDs mirroring) and several different applications run on it. The problem arises when file-intensive jobs (e.g. extracting large archives) run while ...
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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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15 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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Is using nested RAID 6+1+0 a good idea?

Currently I have 24 disks of 500 GB, and I would like to create a bigger nested RAUD using a Dell Power Edge R730 server, having 4 times RAID 6 with six times 500GB each, over them I want to add RAID ...
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38 views

Ubuntu raid - can't boot - mdadm

I was trying to copy the /tmp to another disk (Ubuntu 14.04 server), however after doing so, any command that I typed to the shell started to throw errors. I tried to reboot it, but now it just ...
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32 views

mdadm: replace disk in a 4-disk RAID5 while it resyncs

I'm preparing a server with 4 disks assembled into software RAID5 during Debian 8 installation. Shortly after the system was configured, SMART detected an Offline Uncorrectable Sector error, so I ...
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35 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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30 views

Raid device on rename appended with _0

I am creating various raid configurations. When I create a raid device say 5 with 3 disks mdadm --create /dev/md/md5 --level=5 --raid-devices=3 /dev/sda /dev/sdb /dev/sdc It does create a device ...
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mdadm not assemble after restart

I have 2 disk with the next structure: lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 3,7T 0 disk ├─sda1 8:1 0 2,7T 0 part └─sda2 8:2 0 931,5G ...
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63 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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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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59 views

One disk accessed more than others during md RAID6 rebuild

I am rebuilding one drive of an 8-drive RAID6 (using 'md' Linux software RAID), and have noticed that it doesn't seem to be going as fast as it could, presumably because one of the drives is being ...
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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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74 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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60 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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54 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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51 views

Mdadm raid1 says the last drive attached has failed

I have a software raid1 array. Today I found one of the drives failed to sync, and I got this: $ cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb1[0] sda1[2](F) 153597312 ...
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140 views

Ubuntu 14.04 Software RAID 1 - md0 inactive

I have my root filesystem on /dev/sdc, and a software RAID 1 spanning /dev/sda and /dev/sdb (I think). I physically moved my computer and ran software updates today (either of these could be the ...
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115 views

Replaced SATA controller, software RAID (mdadm) stopped booting: grub rescue> no such disk

I have a relatively old server machine which has no SATA ports on the motherboard (Dell Precision Workstaion 650). Also have a cheap FakeRAID controller (VIA VT6421 Chipset) and two Seagate 3TB drives ...
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Copy centos 6 modify mdadm raid 1 and clone to new mdadm raid 1 ssd

I have: Centos 6.7 grub-install -v grub-install (GNU GRUB 0.97) lsblk two new SSD 128gb Live usb with Parted_Magic_2015.03.06 /boot/grub/device.map # this device map was generated by ...
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mdadm RAID 6 rebuild when remaining drive(s) have bad sectors

I'm setting up a system at work to store some critical data. I will be using 4 x 1TB drives to create RAID6 via mdadm. I did lots of reading and can't find a definite answer to my question: In a 4 ...
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76 views

dracut-pre-trigger rd.md=0 removing md raid activation boot fails

The system is Fedora 22, recently upgraded from Fedora 21. The remaining kernel from Fedora 21 boots. The two kernels installed after the upgrade fail to boot. The system is an Intel S-5000 PAL with ...
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mdadm: can I reconnect a USB disk as SATA without needing a rebuild?

In my server there's an mdadm RAID-1 array consisting of two SATA disks, named sdb and sdc. The sdb disk might fail soon (according to SMART data), and I want to replace it with a newly bought disk. ...
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28 views

mdadm RAID1 won't rebuild

A drive on one of my Hetzner servers failed yesterday. I've replaced it once before, but this time it just will not work. After I copy the GPT to the new disk, I add one of the partitions to the ...
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“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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226 views

Linux- Convert 2 disk raid1 to raid0

I have a linux server (3.19.0) which has raid setup with md (v3.2.5). / is a raid1 device with 2 disks. There was a mistake when installing this machine, instead we need those 2 disks to be in raid0 ...
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Can I convert a single-disk system to software RAID1 without double-copying?

I have read this question: Can I create a "soft" RAID1 array without nuking data? as well as many other tutorials that layout this general process: Create degraded RAID1 array on new drive ...
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53 views

Advice for creating CentOS mdadm software RAID6

EDIT: Solutions to my issue are below I want to create a well optimized RAID6 array with mdadm with an XFS partition on a CentOS system. It'll involve ten ST3000DM001 Seagate 3TB drives and I'll be ...
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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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Linux raid10 on 2 disks

Linux mdadm has some quirks, one of them is building raid10 with only two disks. There are some reports that it's way faster (twice, both in read and write) as RAID1: ...
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RAID10 with 24 drives on Linux

I have an Ubuntu server with attached 24x1TB drives, which I would like to use for storage. I would like to use RAID10 with ext4, but all examples I saw (such as ...
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557 views

NVMe drives write performance in software RAID 1

We have just received two brand new Supermicro servers 1028U-TN10RT+ with 10 NVMe slots, two of them with Intel DC P3600 800gb hard drives. We were eager to test the performance of the drives as the ...
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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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Different free disk space figures in df output after complete rsync -Sap transfer

I did "rsync -Sap --numeric-ids --delete-during /mnt/RAIDVault/ /mnt/RAIDVault-BACKUP/" intending to bring two storage units in sync (having identical content) but ended up with different amount of ...
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84 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 ...
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How do I troubleshoot my RAID array?

I just checked into my RAID array this morning and what I got is: $ cat /proc/mdstat Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] md1 : active raid1 sdc7[0] ...
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md raid10: how to make sure that replicated data is stored in right place?

When creating classic mirrored raids, it's usual to locate copies of data on disks of different kinds. In this case you would use a mix of disks of different series and manufacturers. That reduces the ...
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Debian server has degraded mdadm array on every boot

I have a Debian server with MD raid (2 actives, one spare): Personalities : [raid1] md1 : active raid1 sdc2[0] sdb2[1] sda2[2](S) 1068224 blocks [2/2] [UU] md0 : active raid1 sdc1[2](S) ...