RAID - Redundant Array of Independent Disks. A Storage technology to provide redundancy and performance, to reduce I/O bottlenecks involved in using multiple disks for large storage.

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4answers
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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 ...
21
votes
2answers
15k views

RAIDing with LVM vs MDRAID - pros and cons?

In his answer to the question "mixed raid types", HBruijn suggests using LVM to implement RAID vs the more standard MDRAID. After a little investigation, it seems LVM also supports RAID ...
15
votes
2answers
14k 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 ...
12
votes
3answers
5k 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 ...
11
votes
1answer
22k 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 /proc/...
11
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3answers
40k views

How to mount a disk from destroyed raid system?

I have a horrible situation where I have to restore data from damaged raid system in a rescue Debian Linux. I just want to mount them all to /mnt/rescue in read only modus to be able to copy VMWare ...
9
votes
3answers
2k views

mdadm: can't remove components in RAID 1

I have my /boot partition in a RAID 1 array using mdadm. This array has degraded a few times in the past, and every time I remove the physical drive, add a new one, bring the array being to normal, ...
9
votes
2answers
1k views

Choosing filesystem for a 16TB Raid

I'm just putting together a machine with eight 2TB disks. I will be using Raid 6 (12TB of usable capacity) on top of them, but I'm not sure whether I should make LVM on top of the RAID, or what ...
8
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1answer
3k 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. ...
8
votes
1answer
4k views

Linux: LUKS and multiple hard drives

I have a Debian Linux system (amd64) installed on a RAID-1 system encrypted device (LVM on LUKS) and will have a RAID-6 of >=4 disks where I'll put my data (LUKS and maybe LVM). I think the basic ...
8
votes
1answer
141 views

md raid5: translate md internal sector numbers to offsets

TL;DR summary: Translate an md sector number into offsets(s) within the /dev/mdX device, and how to investigate it with xfs_db. The sector number is from sh->sector in linux/drivers/md/raid5.c:...
7
votes
6answers
4k 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 ...
7
votes
3answers
17k views

Using mdadm --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 --...
7
votes
2answers
826 views

In place upgrade of a software raid 5 array

I run a software raid array for my backups, but my data has outgrown capacity. considering I have a full 2.4TB array with 5*600GB drives and also have 5*2TB drives I would like to swap in. What ...
7
votes
1answer
5k views

Problem Installing UBUNTU 14.04 (AND Mint 16, which is based on UBUNTU 13.10) as dual boot on RAID 0 with Windows 8.1

Ok, I know that there is Dual-Boot Ubuntu 14.04 and Windows 7 on FakeRAID Installation error - question marks "????..." and that that post has some answers for me, but I don't know if it ...
7
votes
0answers
331 views

Couldn't fill logical volume maps [closed]

So I have a big problem here. On our server, there is an LVM raid with one volume group called raid. It contained two volumes, secured and unsecured and some unallocated space. Today I tried to remove ...
6
votes
4answers
11k views

Mounting multiple devices at a single mount point on Linux

Is there a way to mount multiple hard drives to a single mount point? Let's say I run out of space on /home and decide to add an extra hard drive to the computer. How do I scale the space on a mount ...
6
votes
1answer
16k views

How to setup a RAID system using USB sticks as storage media

I want to create an inexpensive self-hosted private git server with redundant storage. To that end I have bought a Raspberry Pi and configured both git and ssh on the Pi. I can access the Pi both from ...
6
votes
2answers
1k views

Is a ZFS storage array portable across operating systems & CPU Architectures?

I know that ZFS is available on variety of operating systems Solaris, Illumos, Linux, BSD etc. Suppose I have a bunch of disks that are part of ZFS raid file system that was created on Linux, could ...
6
votes
1answer
233 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
2answers
1k 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 ...
6
votes
2answers
2k 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
5answers
1k views

Consumer Level software RAID5 and LVM

Hi I am going to build a 6 drive consumer level RAID 5 (10TB) with Ubuntu10.10 and using EXT4 as filesystem, and OS on another drive. Question: Should you use LVM on top of the RAID5 or should just ...
5
votes
3answers
13k 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 ...
5
votes
3answers
1k 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 ...
5
votes
1answer
124 views

Is it sensible to use multiple LVM layers with mdraid

I'm building up a home server that will be used for a handful of different things. I'd really like to try a Btrfs raid 1 array for a large data store, but I'm using CentOS 7 (older kernel although it'...
5
votes
1answer
417 views

How mdadm recognizes which device is right one to sync others with

Imagine you have mdadm raid1 with 2 disks. Then you turn off the server, split the disks each one to different machine and boot both of them, so they will become slightly inconsistent Now you turn ...
5
votes
1answer
23k views

How to get details of RAID devices both soft and hard?

I want to check if my server has RAID configured both soft and hard. I tried some commands on my server (Suse Enterprise Edition 11): **ms:~ # cat /proc/mdstat Personalities : unused devices: <...
5
votes
1answer
1k views

Alternatives to LVM

I was thinking about alternatives to combine several HDDs together. The only options I know so far are using LVM and/or RAID. The thing is, using LVM, I will most probably lose all data, if one ...
5
votes
1answer
160 views

Why does mdadm believe my raid1 “has failed so using --add cannot work”?

TLDR: Trying to add a blank partition to a degraded RAID1 with mdadm 3.3.2 (Debian Jessie) fails, saying the (perfectly working!) array has "failed" and "--add cannot work". Is it telling me of a real ...
5
votes
3answers
4k views

Partitioning EFI machine with two SSD disks in mirror

I have two SSD disks, I want to put them in a software mirror RAID. But whatever I do the OpenSuSe installation keeps telling me that due to the partitioning scheme he won't be able to install the ...
5
votes
1answer
1k views

Prevent Debian from auto-assembling RAID at boot

I set up a Debian wheezy (7.6), installed openmediavault, and created a software raid 5 with that. It is listed at /dev/md127. Now I want to move that to a virtual XEN VM. To do so, I have to stop ...
5
votes
1answer
2k 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. ...
4
votes
2answers
163 views

Where did 47gigabytes of space go?

Clean installation od Debian squeeze 6.0.6 x64 on intel atom 230, with 3 HDDs, with 3x500GB. df -h shows : datastore size used free % mounted /dev/md0 917G 909M 870G ...
4
votes
3answers
443 views

What would be a good choice for an elastic file system (for adding storage at a later date)?

I'm currently running a Debian 6.0 server with EXT3, but I'd like to move over to Arch. It's being used as a file server right now with a 1TB drive in it (of which 650GB in it is used). What I'd like ...
4
votes
2answers
310 views

RAID setups questions

I have a RAID setup questions My mobo supports hardware RAID, my question is, should I use the board's RAID system or freeNAS/Ubuntu's software RAID system? I realize performance is better with h/w, ...
4
votes
2answers
8k views

Strange error message during CentOS 6.5 installation regarding disk containing BIOS RAID metadata?

While attempting to use an old 40GB HDD to setup a kind of junky though usable Athon 1GHz system I ran into the following error during the HDD identification/partitioning phase of the installation: ...
4
votes
4answers
1k views

Reassemble mdadm-raid5

A friend of mine has a mdadm-raid5 with 9 disks which does not reassemble anymore. After having a look at the syslog I found that the disk sdi was kicked from the array: Jul 6 08:43:25 nasty kernel:...
4
votes
1answer
1k 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
1answer
3k views

Why does btrfs allow to create a raid1 with mismatched drives?

I'm creating a btrfs using sudo mkfs.btrfs -m raid1 -d raid1 <small-disk> <large-disk> or sudo mkfs.btrfs -m raid1 -d raid1 <large-disk> <small-disk> it creates the fs with ...
4
votes
1answer
4k 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 ...
4
votes
1answer
215 views

218TB XFS LVM filesystem. 144TB Free. Error message “No Free Space Left on Device”

I have a giant 218 TB RAID6, across LVM. It is actually 2 separate RAID6s joined together through LVM to form one giant RAID6. df -h shows all space was available, and I mounted to /share. I wanted ...
4
votes
3answers
2k views

Software RAID 5 and 6 stripe size: why smaller is less efficient?

I read here and then that small stripe size is bad for software (and maybe hardware) RAID 5 and 6 in Linux. The rare benchmarks I saw fully agree with that. But the explanation given by everybody is ...
4
votes
2answers
2k 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 ...
4
votes
1answer
8k 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 ...
4
votes
1answer
4k views

How to install Debian Jessie properly onto multiple devices with BTRFS in mode RAID 1?

As a short introduction I'm going to tell you, what kind of setup I have and what I want to achieve. After that I try to explain my problem. Since this is my first question on U&L I have to ...
4
votes
1answer
187 views

ext4 directory lists as a file

I'm working with a large (8TB) EXT4 filesystem in linux. After a power outage, the filesystem wouldn't mount. fsck is taking weeks to complete, but i ran testdisk and i'm able to see my partition ...
4
votes
1answer
462 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 ...
4
votes
1answer
786 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 ...
4
votes
1answer
320 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 ...