A linux utility used to manage software RAID devices.

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apt-get update mdadm scary warnings

Just ran an apt-get update on one of my dedicated servers to be left with a relatively scary warning: Processing triggers for initramfs-tools ... update-initramfs: Generating ...
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Slow md RAID-1 array

We have some problems with very slow disk response on our server. I checked iostat (iostat -d -x 30) and have some problems with its interpretation: Device: rrqm/s wrqm/s r/s w/s ...
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3answers
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Can't resize2fs - combination of flex_bg and !resize_inode

I recently set up my first software raid with mdadm and after adding more disks to the raid I am unable to resize the filesystem to the full size of the raid. I created a single (~16TB) filesystem on ...
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2answers
972 views

Degraded RAID-5 array with lvm2 lost superblock and partition table

I have a RAID-5 array of 4x1TB hard disks with one lvm2 partition on Ubuntu Linux 10.04 LTS. One of the disks has failed. I have re-assembled the array without this failed disk but now mdadm --examine ...
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1answer
720 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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1answer
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mdadm+zfs vs mdadm+lvm

This may be a naive question since I'm new to this and I cannot find any results about mdadm+zfs, but after some testing it seems it might work: The use case is a server with RAID6 for some data that ...
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1answer
391 views

3 drives fell out of Raid6 mdadm - rebuilding?

i had an mdadm raid6 array with 13x1TB drives. Within 10 minutes 3 of these drives fell out of the array... we assume bad cable to the controller card and replaced, however now we need to get the ...
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1answer
563 views

Debian installation on software RAID (lilo.conf configuration)

Debian installation program has created lilo.conf: boot=/dev/md1 root=/dev/md1 raid-extra-boot=mbr-only But when i configure lilo i usually put these lines disk=/dev/md1 sectors=63 heads=255 ...
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Failed MDADM Array With Ext.4 Partition - “e2fsck: unable to set superblock flags on /dev/md0”

Had a power failure and now my mdadm array is having problems. sudo mdadm -D /dev/md0 [hodge@hodge-fs ~]$ sudo mdadm -D /dev/md0 /dev/md0: Version : 0.90 Creation Time : Sun ...
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Resize openSUSE 12.3 GPT ext4 partitions in a RAID1 disk array

I have a software raid configured (/dev/md2) which has assigned the partitions sda3 and sdb3 from two 3TB disks (sda and sdb). The partition types are GPT not LVM and file system is ext4. Now, the ...
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1answer
529 views

EC2 disk goes to 100% util, but fine after reboot

We've been running some production services on Amazon EC2 for a while, using mainly t1.large and t1.xlarge instances (non-EBS). Every so often one of the attached (ephemeral disks) will get into a ...
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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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2answers
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Mdadm won't create an array larger than 10TB

I have a server with six 4TB drives running Ubuntu 14.04 LTS. One of the drives is used for the system/OS I wanted to use the other 5 drives to get as close to 20TB of storage as possible It's a ...
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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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3answers
368 views

Degraded partition in RAID5 system

I've got a server running Debian Squeeze and a 3x 500 GB-drive RAID5 system which I haven't set up myself. When booting, the status of one partition in the RAID-array seems to be bad. md: ...
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1answer
606 views

mdadm RAID1 to RAID6

I've got a RAID1 array. I'm buying 4 more disks of equal size (they're the same model drives) and I'm trying to enumerate my options for a safe upgrade. Ideally they'll be one large ext3 volume. ...
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1answer
280 views

Does growing a RAID 5 destroy the data on the RAID?

For a linux software RAID using madadm, does adding a harddrive and growing onto the RAID, destroy the data that's already on the RAID or does it preserve everything?
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Raid 5 with 4 disks on Debian automatically creates a spare drive

I'm trying to to create a RAID 5 with 4x 2TB disks on Debian 6. I followed the instructions from: http://zackreed.me/articles/38-software-raid-5-in-debian-with-mdadm I created the raid with following ...
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1answer
965 views

Growing a RAID5 using mdadm with multiple drives?

I have a RAID5 array that consists of 3, 2TB drives. I want to add 2 more drives. The tutorials involve adding a single drive to an array, such as this: https://raid.wiki.kernel.org/index.php/Growing ...
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Is mdadm Raid-1 Over A Network File Share Possible?

I am using 64bit CentOS 5.5 I know it's possible to set up software RAID1 using mdadm using a physical hard disk and a RAM disk. Is it possible to set up software RAID1 with mdadm using a NFS mount ...
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Recover RAID-5 that was already running in degraded mode (lost a second disk)

this is silly, this has happened before and I figured out how to fix it and it was fine. I'm running 4 500GB SATA drives in a RAID-5 on Ubuntu 7.10 server. One of the disks failed (actually I think ...
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2answers
875 views

Linux Software RAID1 Rebuild Completes, but after reboot, its degraded again

I have been beating my head with an issue here, and I'm now turning to the internet for help. I have a system running Mandrake Linux, with the following configuration: /dev/hda - This is a IDE ...
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2answers
586 views

Reading off of MDADM drives after server died

I had a 2-drive RAID-1 array running on ubuntu, which I had forgotten about. The host I was running them on is now dead, leaving me with these two disks. How can I get data off of them? If I dump ...
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321 views

reshaping raid and growing raid

This is a two part question. 1) Can you reshape raid 5 to 6 with mdadm on linux (fairly sure you can, but cant get mdadm to accept it) 2) Can you do 1) while also growing the array in one go ?
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128 views

Is there any way to build a linux software raid system without all drives?

I'm building a raid1 (ok it will probably be a raid10,f2 but the difference with 2 drives... isn't much) system with 2 1TB drives. However, 1 of the drives I've ordered is bad so I'm RMA-ing it. I'm ...
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1answer
580 views

Linux Raid: mystical md_d device

I have a 64bit Ubuntu Jaunty server (kernel 2.6.28-17-server) installed on two SATA disks (sdc and sde) in a mirror RAID, this being my current raid configuration: cat /proc/mdstat Personalities : ...
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72 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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1answer
502 views

Software RAID1 ready to fail - How can I degrade manually?

I have a Centos 5.4 server in production with 2 drives in software RAID1. The last days /var/log/messages has a lot of messages, showing that one of the drives is ready to fail: Sep 23 00:48:38 ...
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924 views

How to diagnose intermittently slow raid data transfer rate?

I have an encrypted RAID6 set up on Centos 5.5. When I transfer a large 10gb file from the raid to my computer it will pause at around 4-5gb and again at 9gb. The data transfer drops from 25mb/sec to ...
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Creating backup disk image of RAID 1 array (MDADM)

We have some servers that run in very harsh environments (research vessel) that need to have high-availability. We have software RAID 1 for some measure of resiliency, along with proper data backups ...
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1answer
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Linux Mdadm + LVM recovery

I recently reinstalled my Ubuntu server with 10.04, and am having trouble reactivating the LVM partition which houses all my non-critical data. /dev/sda, /dev/sdb, /dev/sdc, and /dev/sdd are all ...
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1answer
113 views

Best way to RAID 4 x Intel SSD 910 for PostgreSQL

I have a Linux (debian/ubuntu) server with 4 x Intel SSD 910 800GB pcie that I need to RAID together. The biggest problem with these card is that they give you 4x200GB drives that you cant ...
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1answer
84 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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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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1answer
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How do you set up RAID1 with both disks bootable on Debian/Ubuntu?

In Debian 6, new installation, what is the recommended way of setting up a software RAID1 array so that the system is bootable from both disks? I have heard that people that don't know what they are ...
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Removing a device in “removed” state from Linux software RAID array

My workstation has two disks(/dev/sd[ab]), both with similar partitioning. /dev/sdb failed, and cat /proc/mdstat stopped showing the second sdb partition. I ran mdadm --fail and mdadm --remove for ...
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1answer
571 views

mdadm kernel log messages explained

Welcome. I try to recover from linux software raid failure. I am in a process of recreating the superblocks based on a syslog from the system when it was healthy. The log speaks about 2 md devices, ...
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1answer
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Linux raid controller (LVM/MDADM)

Today I'm in a very bad place. A production raid array went down. The controller failed. After unmounting the file systems and killing all processes, I changed the hardware controller. On restarting ...
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1answer
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Unresponsive mdadm

I have a raid 5 mdadm raid array set up with 6 drives and a hot spare on an Ubuntu 11 server. There are a couple samba shares on the drive, and until today, they were working well. A couple hours ago ...
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Odd mdadm output: --examine shows array state failed, --detail shows everything clean

The setup: 8 disks in a mdadm-managed RAID5 array (/dev/md0, made from /dev/sdc through /dev/sdj). One disk (/dev/sdh) is showing SMART errors (increasing pending sector count) so I'm looking to ...
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ext3 format options

I'm creating a ext3 filesystem on top of a software raid5 (md) and I'm wondering what are the best parameters when creating the filesystem (with mkfs.ext3) and while mounting. RAID5 chunk size is ...
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1answer
179 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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Linux RAID mdadm: what does 'Events' mean?

When I type mdadm --detail /dev/md0 I get a lots of useful information most of which I understand. However I also get a line that reads: Events : 0.710 Where the number varies. Naively, I ...
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mdadm: Growing a RAID0 Array Weirdness

I have created 3 RAID0 arrays using mdadm on 3 Rackspace CloudServers using Rackspace's CloudBlockStorage as their devices. Each array has their own set of CBS volumes. RS-CBS has an upper limit of ...
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820 views

reliably and automatically determine connection path of physical position of HDD from /dev/sdX device file

This is kind of a FAQ, but all the answers I found so far are not suited for full automation, which is what I need. So here it goes again. In Linux: Is there a reliable way to resolve the udev ...
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mdadm: hot remove failed for…

My RAID1 is degraded and I need to replace /dev/sdb. However, I could mark /dev/sdb5 (in /dev/md1) as failed and removed it, but I can't do the same with /dev/sdb1 (/dev/md0 which is mounted on /): ...
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Why is my mdadm raid-1 recovery so slow?

On a system I'm running Ubuntu 10.04. My raid-1 restore started out fast but quickly became ridiculously slow (at this rate the restore will take 150 days!): dimmer@paimon:~$ cat /proc/mdstat ...
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1answer
201 views

mdadm raid6 recovery reads more from one drive?

I just replaced a fault drive in my raid6-array (consisting of 8 drives) during the recovery I did notice something strange in iostat. All drives are getting the same speeds (as expected) except for ...
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289 views

Putting a spare Raid device back to active state

I have a problem with my Raid setup. I have 3 disks in my Raid: md2 : active raid5 sdc3[3](S) sdb3[4](S) sda3[0] 2925532672 blocks level 5, 64k chunk, algorithm 2 [3/1] [U__] md1 : active ...
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Why is my HDD partition a character special device?

I have a bunch of old 1T disks with an mdadm array on them. They had been out of commission for awhile, but yesterday I slotted them into a server running an up to date Debian Jessie. Eventually I ...