A linux utility used to manage software RAID devices.

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31
votes
4answers
13k views

Recover RAID 5 data after created new array instead of re-using

Folks please help - I am a newb with a major headache at hand (perfect storm situation). I have a 3 1tb hdd on my ubuntu 11.04 configured as software raid 5. The data had been copied weekly onto ...
26
votes
6answers
42k views

How to interrupt software raid resync?

I want to interrupt a running resync operation on a debian squeeze software raid. (This is the regular scheduled compare resync. The raid array is still clean in such a case. Do not confuse this with ...
16
votes
3answers
8k views

Can you change the metadata version on an existing array?

So grub requires metadata version 0.90 I'm wondering if I can change my existing arrays to use that instead of the default which is 1.2. That way I don't have to go about a reinstall. If yes, how can ...
15
votes
2answers
2k views

Verify A Partition is Aligned in Linux With RAID and LVM

Does anyone know the steps to verify that a XFS filesystem on top of LVM and md RAID is properly aligned on an array of 4096 Byte aka "Advanced Format" sectored disks? Some references are: ...
13
votes
4answers
10k views

Best way to grow Linux software RAID 1 to RAID 10

mdadm does not seem to support growing an array from level 1 to level 10. I have two disks in RAID 1. I want to add two new disks and convert the array to a four disk RAID 10 array. My current ...
12
votes
3answers
2k views

mdadm raid5 recover double disk failure - with a twist (drive order)

Let me acknowledge first off that I have made mistakes, and that I have a backup for most but not all of the data on this RAID. I still have hope of recovering the rest of the data. I don't have the ...
10
votes
3answers
11k views

How do I rename an mdadm raid array?

I have assembled a new raid array to replace an old one. However, this new array got assigned an automatic name of /dev/md127 and I want to rename it to /dev/md3, so that I don't have to change ...
9
votes
2answers
13k views

How do I move a Linux software RAID to a new machine?

I have a newly built machine with a fresh Gentoo Linux install and a software RAID 5 array from another machine (4 IDE disks connected to off-board PCI controllers). I've successfully moved the ...
8
votes
2answers
2k views

Linux mdadm software RAID 6 - does it support bit corruption recovery?

Wikipedia says "RAID 2 is the only standard RAID level, other than some implementations of RAID 6, which can automatically recover accurate data from single-bit corruption in data." Does anyone know ...
8
votes
4answers
3k views

Using 4k drives with md/LVM/dm-crypt

I know that I have to align my 4k drives by a multiple of 8 sectors, but what about md-RAID / LVM / dm-crypt? How do I tell these layers that my drive is 4k? If they don't respect the 4k sector size, ...
8
votes
2answers
1k views

Linux Software Raid 10 hung after 1 drive failed, mdadm will not let me force remove the faulty device

I have a Linux software raid 10 setup consisting of 5 RAID 1s (Two drives per mirrored setup) and a RAID 0 across all 5 RAID 1 pairs. To test that none of the drives were going to fail quickly under ...
7
votes
4answers
2k views

Software RAID10 for later growth

I'm wondering what the best practice is for creating RAID10 in software on Linux with the ability to later grow by adding disks or expanding volumes underneath. I'm using EBS on Amazon, I want to ...
7
votes
1answer
3k views

Can I create a “soft” RAID1 array without nuking data?

I've just bought two 1.5TB disks with the aim of creating a 1.5TB RAID1 array. In my infinite lack of wisdom (and a lack of space inside the computer - it already had 6 disks), I stuck one in, ...
7
votes
2answers
3k views

LVM2 vs MDADM performance

I've used MDADM + LVM2 on many boxes for quite a while. MDADM was serving for both RAID0 and RAID1 arrays, while LVM2 where used for logical volumes on top of MDADM. Recently I've found that LVM2 ...
7
votes
2answers
257 views

Linux software raid fails to include one device for one RAID1 array

One of my four Linux software raid arrays drops one of its two devices when I reboot my system. The other three arrays work fine. I am running RAID1 on kernel version 2.6.32-5-amd64. Every time I ...
6
votes
4answers
12k views

How to create a software raid5 array without a spare

I am trying to create a software raid5 array using mdadm: $ linux # mdadm --create --verbose /dev/md0 --level=5 --raid-devices=4 --spare-devices=0 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 mdadm: ...
6
votes
4answers
458 views

mdadm: Replacing array with entirely new drives

I have a server with three 500GB drives, with most of my data in a RAID5 configuration spanning the three of them. I just purchased and installed four 1TB drives, and the intention is to move off of ...
6
votes
1answer
4k views

mdadm and 4k sectors (advanced format)

There are numerous questions on Serverfault about aligning 4k sectors disks, but one thing is not really clear to me yet. I successfully aligned my RAID1+LVM. One of the things I did was use mdadm ...
6
votes
2answers
330 views

RAID1: Which disk will be mirrored?

How does a RAID1 system determine which disk to use as the source and which disk to use as the destination when mirroring? Assume for instance the following scenario: A RAID1 array is created with ...
6
votes
1answer
9k views

Ubuntu server, gpt partition table, mdadm, grub boot fail

Basic working system details: I used the Ubuntu 12.04 server CD to install a server. I have 4 disks. On all disks I did the following, similar to this howto : created a 2GB swap partition created ...
6
votes
3answers
6k views

How to resize RAID1 array with mdadm?

I've running Ubuntu 11.04 (kernel 2.6.38-11). I replaced 2x160GB with 2x500GB drives. They are configured as RAID1. The partition tables show the right sizes. Here's sfdisk: # sfdisk -d /dev/sdb # ...
5
votes
3answers
2k views

Convert a software raid volume from ext3 to ext4 (or ext2)?

I have an mdadm created software raid volume in my ubuntu linux 11 machine. It is NOT the boot drive. It is a software raid 5 configuration made from 3 large sata drives. When I created it ...
5
votes
5answers
12k views

linux LVM mirror vs. MD mirror

I think I remember making some mirrors years ago with LVM, and I don't remember this "log" thing. Or maybe I made the mirror with mdadm and put LVM on top. That must be it. What is the LVM log for ...
5
votes
2answers
3k views

Is my hard drive about to die?

I have two hard drives set up as a RAID 1 array on my server (Linux, software RAID using mdadm) and one of them just got me this "present" in syslog: Nov 23 02:05:29 h2 kernel: [7305215.338153] ...
5
votes
3answers
3k views

Linux Software RAID1: How to boot after (physically) removing /dev/sda? (LVM, mdadm, Grub2)

A server set up with Debian 6.0/squeeze. During the squeeze installation, I configured the two 500GB SATA disks (/dev/sda and /dev/sdb) as a RAID1 (managed with mdadm). The RAID keeps a 500 GB LVM ...
5
votes
1answer
2k views

Why do I get a DegradedArray event with mdadm

Just so we're clear on what's happening: I bought 4 new sata 2 drives, with the intent of using them in a raid5 all drive are fully recognised by both my bios and my linux box (gentoo) I created a ...
5
votes
1answer
618 views

How to force mdadm to use udev device names rather than /dev/sdX

The question is mostly in the title already. mdadm and /proc/mdstat insist on listing md members by their "traditional" /dev/sdX names. What I want is for them to use the newer udev device names ...
5
votes
1answer
955 views

Use cases for “mdadm --create” vs. “mdadm --build”?

From the mdadm man page, --build section: This usage is similar to --create. The difference is that it creates a legacy array without a superblock. ^^ So no superblock with --build. 10-4. ...
5
votes
1answer
216 views

Recovering linux software RAID array without removing it's items

I have linux software raid (RAID10), md2 : active raid10 sda6[4](F) sdd5[3] sdc5[2] sdb6[1] 390620160 blocks 64K chunks 2 near-copies [4/3] [_UUU] which has degraded state. Can i start recovery ...
5
votes
2answers
4k views

Ext4 superblock corrupted after successful(?) mdadm grow and resize2fs

Some system details AMD Phenom II X6 1090T, 16GB DDR3 1600 running 11.04 natty, 2.6.38-8-server Raid in question consists of 5 SATA drives; 4 Samsung, 1 Western Digital; 500 GB each Drives are ...
5
votes
1answer
3k views

Is it safe to shutdown a machine while rebuilding/recovering/growing a RAID5 array that was built with mdadm

I have recently started a recovery on my 5-drive RAID in my file-server, and it says it'll take 691+ minutes to complete. I was wondering what would happen to the process if the machine lost power - ...
5
votes
1answer
616 views

Home-grown SAN — topology ideas?

I'm interested in hand-rolling a SAN solution on Linux with the following technologies: iscsi mdadm raid lvm multipath xfs/gfs/??? teamed NICs Hardware-wise, I'm thinking of 2 x gigE (or better) ...
5
votes
3answers
2k views

Why mdadm's RAID-1 is resyncing from scratch despite of the bitmap?

# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 nbd0[3] sda10[0] 53246315 blocks super 1.2 [3/1] [U__] [>....................] recovery = 1.0% (537088/53246315) ...
5
votes
1answer
1k views

Linux; What is stripe_cache_size and what does it do?

I am currently building a software RAID under Linux using mdadm utility and I've read a few articles that describe how to increase the stripe_cache_size value for that RAID and how to calculate an ...
5
votes
2answers
488 views

mdadm: Which disk is being rebuilt?

I noticed my software RAID1 degraded, and wanted to figure out which of the two disks in the array is being rebuilt/re-synced since they both show as being up. I am hoping someone can shed some light ...
5
votes
3answers
3k views

Why does mdadm write unusably slow when mounted synchronously?

I have a 6 disk raid6 mdadm array I'd like to benchmark writes to: root@ubuntu:~# cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md0 : active raid6 sda[0] sdf[5] sde[4] sdd[3] sdc[2] ...
5
votes
1answer
324 views

Linux mdadm --grow RAID6: Something wrong - reshape aborted

I have a RAID60 that I want to expand. The current is: 2 axles each having 9 disks + 2 spares. The future is: 4 axles each having 10 disks + 1 spare. So I need to do some --grow to reshape the ...
5
votes
3answers
333 views

file corruption on read/write 2.6.32-22-server (happens across many kernels)

I'm having an issue where after the server has been up for a period of time (~week/few days) the server will start reading corrupt data. For instance when I run a sha1sum of a file after a fresh boot ...
4
votes
2answers
2k views

Daemon to verify Linux md raid

Is there a way to periodically verify that a linux software raid is valid and has no errors? Like a daemon that would scan all blocks and verify them.
4
votes
3answers
944 views

mdadm RAID 5 Failed with 2 Drives while rebuilding

I have a RAID 5 array with 3 Disks (sdb sdc sdd) Over last weekend I was prompted that sdd had failed. so replaced the drive, added it back into the array and let it rebuild (1.5TB) It stopped at ...
4
votes
2answers
20k views

How do I get mdadm to auto assemble my raid array?

After upgrading to Ubuntu 9.04, my raid 5 array is no longer being assembled correctly. Right now, from boot, it will start a raid array using ata-MAXTOR_STM3500630AS_9QG03T0L-part1, at /dev/md0, but ...
4
votes
3answers
5k views

explain md's raid10,f2

I know how most of the various RAID's work. But I stumbled on the recommended raid10,f2 mode while researching linux software raid. I don't really understand how it works on 2 or 3 disks. could ...
4
votes
2answers
3k views

Would you recommend mdadm raid10 for EC2?

I read a blog article somewhere that RAID10 on EC2 cuts down performance by half compared to RAID0. But when you have critical database data on the volumes, how else do you prevent data loss in case ...
4
votes
1answer
345 views

Rebuild mdadm RAID5 array with fewer disks

I have a 4 disk RAID5 array, one of which is starting to fail according to smartd. However, since I'm using less than half the space on /dev/md0, I'd like to rebuild the array without the failing ...
4
votes
3answers
674 views

What are the advantages and disadvantages of constructing an mdam array from whole disks vs. partitions?

Let's say I've got six identical drives and I'm going to use them all in a RAID10,f2 array constructed using mdadm. I've always put a single partition on each disk and constructed the array from ...
4
votes
2answers
931 views

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 ...
4
votes
2answers
3k views

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 ...
4
votes
4answers
2k views

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 ...
4
votes
2answers
924 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 ...
4
votes
1answer
500 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 ...