A linux utility used to manage software RAID devices.

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14
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3answers
28k views

How to check mdadm raids while running?

I'm starting to get a collection of computers at home and to support them I have my "server" linux box running a raid array. Its currently mdadm raid1, going to raid5 once I have more drives (and ...
12
votes
2answers
6k views

What's the difference between mdadm state “active” and state “clean”

I have two different computers with different RAID5 arrays. When I run the command mdadm --detail /dev/md0 one drive reports "active" while the other reports "clean" for the "state" field. What ...
9
votes
2answers
3k views

Grow/resize RAID when upgrading visible size of disks

I originally created a software RAID using a controller that could only address 2TB per disk. The disks are 3 TB disks. It worked fine, but only used the first 2TB of each disk. I have now changed ...
9
votes
1answer
407 views

How do I recover a broken software RAID5 array?

Ack, I think I screwed up bad. I had a power failure on a RAID5 array which caused the metadata to be inconsistent between drives. I followed the advice here except a case of fat fingers caused me to ...
8
votes
1answer
5k views

grub error “superfluous RAID member” on update-grub

My system (wheezy/sid: 2.6.32-5-amd64 #1 SMP x86_64 GNU/Linux) is running fine - I'm just wondering what some messages mean. I have two mdraid arrays running up on my system. Here's cat /proc/mdstat: ...
8
votes
2answers
846 views

What keeps one side of an rsync so busy?

I've got a Debian machine on my LAN serving as a backup server for the others. It has four HDDs combined into a software RAID 5 md device, on that an LVM, and on that btrfs. Backups are made using ...
8
votes
1answer
1k 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 ...
7
votes
3answers
396 views

Difference between UUID from blkid and mdadm?

Can someone explain the difference between the UUID's reported by blkid and mdadm? On one of our CentOS systems, for example: [root@server ~]# blkid | grep /dev/md1 /dev/md1: ...
6
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1answer
2k views

mdadm Raid5 gives spares missing events

I succesfully builded up a raid5 array on debian testing (Wheezy). As the manpages and further tell, the array would be created as an out of sync array with just a new spare injected to be repaired. ...
6
votes
1answer
53 views

Should I use `mdadm --create` to recover my RAID?

There's this guy that keeps telling me that we shouldn't use mdadm --create to recover our RAID arrays, that it's worse than evil, is an error. Why is that? I mean I should get my RAID working again, ...
6
votes
1answer
10k views

mdadm raid1 and what chunksize (or blocksize) on 4k drives?

I want to use two 3 TB drives in a mdadm raid1 setup (using Debian Sequeeze). The drives use 4k hardware sectors instead of the traditional 512 byte ones. I am a bit confused because on the one hand ...
6
votes
6answers
3k views

Pros and cons of software Parity-RAID (e.g. RAID5)

I was recently told about some problems concerning Parity-RAIDs without a non-volatile cache. More exspensive HW-controllers do have battery-powered caches to finish write-operations in case of power ...
6
votes
1answer
237 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 ...
6
votes
2answers
1k views

Will the system make sure that mdadm is sync-ed before completing a reboot?

This is a follow up to my crazy mdadm problem. I'm trying to figure out what might have caused sda to get out of sync in the first place. The only thing I can think of is that I had just run a bunch ...
5
votes
2answers
335 views

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 ...
5
votes
1answer
3k 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 ...
5
votes
2answers
3k views

/dev/md127 refuses to stop. No open files

So I'm trying to stop /dev/md127 on my Ubuntu 12.10 box. It was set up as RAID1, but I'm trying to move everything (well, rename) to md0. I read that renaming isn't possible, so I'm trying to remove ...
5
votes
3answers
3k views

Using mdam --examine to write mdadm.conf

I'm trying to script the RAID setup for a (growing) number of identical servers. The advice I've seen for using mdadm suggests that once the RAID array has been created you can run mdadm --examine ...
4
votes
3answers
2k views

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 ...
4
votes
1answer
729 views

Unable to mount raid on my NAS, trying to rescue the data, how should I proceed?

A short backstory: something happened on my Synology NAS, apparently a buggy mailserver program that came with an update stopped the device from seeing the 2x3TB drives I have. After a lot of ...
4
votes
4answers
1k 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 ...
4
votes
3answers
623 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 ...
4
votes
1answer
5k views

Using UUID's with mdadm

I'm using GPT as my partitioning scheme. I check the UUID's of my partitions: # ls -l /dev/disk/by-partuuid/ total 0 lrwxrwxrwx 1 root root 10 Oct 18 22:39 0793009a-d460-4f3d-83f6-8103f8ba24e2 -> ...
4
votes
2answers
2k views

what is commit=0 for ext4? does mdadm not support it?

I see this in my dmesg log EXT4-fs (md1): re-mounted. Opts: commit=0 EXT4-fs (md2): re-mounted. Opts: commit=0 EXT4-fs (md3): re-mounted. Opts: commit=0 I think that means that dealloc is disabled? ...
4
votes
2answers
4k 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 ...
4
votes
1answer
114 views

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 ...
4
votes
1answer
419 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 ...
4
votes
1answer
1k views

RAID 10 can not be started

I have a RAID 10 array managed with mdadm which has failed . The symptom was that X has crashed and I was unable to logon from the terminal. I have restarted the computer and /dev/md1 did not start. ...
3
votes
1answer
1k 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 ...
3
votes
2answers
3k views

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. ...
3
votes
1answer
43 views

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 ...
3
votes
1answer
2k 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 ...
3
votes
3answers
614 views

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 ...
3
votes
2answers
221 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 ...
3
votes
1answer
232 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 ...
3
votes
2answers
2k 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 \ ...
3
votes
1answer
521 views

TrueCrypt is destoying mdadm volume

I'm setting up a new file server using the same storage configuration as my existing server, but the procedure is failing and i cannot figure out why. my goal is to create a TrueCrypt volume on top ...
3
votes
1answer
179 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 ...
3
votes
3answers
2k views

RAID5 recovery trying with “mdadm --create … missing”

First how I got in this situation: I had an RAID5 array with disks each 2TB (external USB-disks), I then wanted to create a larger encrypted array. Therefore I got 2 additional disks (also 2 TB each) ...
3
votes
1answer
1k views

installing grub 2 on mdadm, which device?

when installing grub(2) to mdadm devices are you supposed to install it to /dev/sdX or /dev/mdX?
3
votes
0answers
32 views

How to speed up migration from Raid 5 to Raid 6 with mdadm?

Today I started the migration of my Raid 5 to Raid 6 by adding a new disk (going from 7 to 8 disks, all 3TB). Now the reshape is in progress: Personalities : [raid6] [raid5] [raid4] md0 : active ...
3
votes
0answers
25 views

RAID6 scrubbing mismatch repair?

You can initiate a scrub of a mdadm array with echo 'check' > /sys/block/mdX/md/sync_action, and if a bad sector is found, it'll rewrite it automatically (from a mirror or from parity information ...
3
votes
3answers
6k views

Grub2 RAID /boot

I'm using Gentoo on my HomeServer. My HDDs are raid1 mirrored with mdadm. My problem is how to boot the /boot partition correct? /dev/md1 consists of /dev/sdc2 & /dev/sdd2 mounted on /boot In ...
2
votes
2answers
392 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 ...
2
votes
3answers
3k views

Can I create a software RAID 1 with one device

I have a single disk that I want to create a Mirror of, Lets call this disk sda I have just bought another identicle size disk, which we can call sdb. sda and sdb have one partition called sda1 and ...
2
votes
1answer
463 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 ...
2
votes
2answers
958 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 ...
2
votes
2answers
8k views

MDADM - how to reassemble RAID-5 (reporting device or resource busy)

I rather new to the linux scene, and don't have nearly enough experience to actually consider myself somebody that can be trusted with using the system :P Anyhow long story short - I decided to use ...
2
votes
1answer
40 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 ...
2
votes
1answer
361 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 ...