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16
votes
2answers
31k views

How to recover a crashed Linux md RAID5 array?

Some time ago I had a RAID5 system at home. One of the 4 disks failed but after removing and putting it back it seemed to be OK so I started a resync. When it finished I realized, to my horror, that 3 ...
10
votes
4answers
6k views

Linux - Repairing bad blocks on a RAID1 array with GPT

The tl;dr: how would I go about fixing a bad block on 1 disk in a RAID1 array? But please read this whole thing for what I've tried already and possible errors in my methods. I've tried to be as ...
9
votes
2answers
2k 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
348 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 ...
7
votes
2answers
487 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 ...
6
votes
2answers
15k views

lvm devices under /dev/mapper missing

I'm using Debian squeeze, and running LVM on top of software RAID 1. I just accidentally just discovered that most of the links under /dev/mapper are missing, though my system seems to be still ...
6
votes
2answers
5k views

How to raid-mirror existing root partition?

I'd like to mirror my existing root (and only) partition on an SSD to another disk. It should be a sort of RAID-1, just asymmetric*. I know there's the option mdadm --write-behind, which should do it. ...
6
votes
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
2answers
6k views

Is Grub installed to all the MBR of a RAID array by default by the Debian Installer?

If I use the Debian Stable (Squeeze) Installer to install Debian, booting from a RAID1 pair of drives, does it write grub to the MBR of both drives - if not, how should I best protect against a drive ...
6
votes
1answer
168 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
3answers
11k views

How to mount/recover data on a disk that was part of a mdadm raid 1 on another machine?

Some background The disk itself was "worked on" by a friend and is said to be still intact, undamaged and still mountable/recoverable The disk was part of a software raid 1 on Ubuntu 12.04 The other ...
5
votes
1answer
9k 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 ...
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
3answers
239 views

RAID 1 in linux

I'd like to setup RAID 1 with two drives in linux. I don't have a hardware RAID controller and don't want to buy one, so what is the best software RAID option for linux? Note: If it makes a ...
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
3answers
73 views

Poor IO due to LUKS/Software RAID/LVM ordering?

I'm trying to determine if I should re-setup my RAID array due to poor IO performance. First off, the system: i7 920 4 4TB WD 5400 Green drives CentOS 6.3 host Secondly, the disk setup: ...
4
votes
4answers
753 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
1answer
87 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
2answers
3k 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
2answers
297 views

How does Linux md-RAID handle disk read errors?

There are 2 cases: the read command times out at kernel level (30 seconds by default), the drive reports its unability to read a given sector before the kernel lose patience (the case I'm ...
4
votes
1answer
1k views

degraded software raid boot

I've installed Ubuntu 12.04.1 in a new server and set up the 4 hard drives with 3 RAID 1 devices, the configuration is such that the first two drives have md0 (swap space) and md1 (/) with the third ...
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
2answers
5k views

Does Grub2 support putting /boot on a RAID5 partition?

It looks like currently most OS installers insist on putting /boot on a non-RAID partition (or the kind of RAID1 partition that "looks like" a non-RAID partition), even the installers that support ...
3
votes
1answer
30 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
170 views

What are potential consequences of going nuts with sparse file based vdevs for a LVM to ZFS migration?

I've been playing around with ZFS having finally accepted that it's mature enough I shouldn't get burned. Now to migrate the home NAS box which is currently an LVM JBOD set up that's quite full, but ...
3
votes
3answers
268 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
1answer
151 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
949 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
2answers
235 views

raid 1/LVM at the level of directories (aka mknodding a directory)

I just experienced data loss, so I am interested in some form of data duplication. I was thinking of mdadm and companions to raid 1 through software. However, I just want a given, not too big ...
3
votes
1answer
150 views

Can zfs resilvering destroy data with misreported device failures?

I have had a situation where I am moving data into a new zfs raidz pool with four devices, some of them virtual to facilitate the migration. The system completely hung in the middle of a device ...
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
2answers
127 views

RAID Lag-Behind Burst Write

I would like to setup RAID1 so that a ramdisk in the RAID configuration has occasional synchronisation with a physical disk (that is very battery intensive to run, so I hope to let it spinout). Is ...
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
337 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
1answer
113 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 ...
2
votes
2answers
747 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
2k views

Mixing 4k/512 drives with ZFS (FreeNAS)

I have the following drives: Seagate Barracuda ST3200054AS WDC WD20EADS-00S2B0 Samsung HD204UI As far as I understand, the first are ordinary 512 drives while the last is 4096 (Advanced format). ...
2
votes
1answer
22 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
167 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 ...
2
votes
1answer
98 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 ...
2
votes
2answers
308 views

Best way to create RAID on an existing system drive

I want to add another disk as RAID 1 to test my database performance. I am trying to not re-do the whole system, is it possible? Currently I have a single 1TB HDD with one 100GB system partition (and ...
2
votes
1answer
341 views

“error: no such device” at boot in Ubuntu Server 11.10 with Raid1

I have a configuration of 4 HDD's as Raid1 2 pairs of 2 HDD's. First Raid1 pair is for system, so I just made an 40GB space for swap, and the rest of it for the root, the second pair of Raid1 is for ...
2
votes
1answer
342 views

Drive was unable to assemble into the array

I ran mdadm -A /dev/md0 /dev/sda1 /dev/sdb1 Only /dev/sdb1 was loaded into the array though. I have a few more arrays on the same two drives too. Each time the partition on sda failed. dmesg told ...
2
votes
1answer
154 views

Mount an existing RAID 1 Logical Volume after OS upgrade

I just upgraded from Ubuntu 10.04 to Mint 16. The installer did not detect my existing RAID 1 array, and I can't access it anymore. My drives are: SDA - First RAID Disk SDB - Second RAID Disk SDC - ...
2
votes
1answer
44 views

Linux installation in RAID

I am a fairly new systems administrator and I have to configure the RAID on a Linux machine. From my understanding so far, RAID is an array of multiple disks. I have some questions though. Question ...
2
votes
2answers
217 views

Can I create a 2 TB RAID-1 array out of one 2 TB disk and two 1 TB disks while preserving 1 TB of data?

I currently have 1 TB of data on a RAID-1 mdadm array. This array consists of one 1 TB disk and a 1 TB partition on a 2 TB disk. I have now bought a second 1 TB disk, and I would like to use this to ...
2
votes
1answer
1k 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 ...
2
votes
3answers
921 views

Advantages/Disadvantages of installing GRUB on a software RAID?

What Advantages are there to installing GRUB on a software RAID-1? What Disadvantages are there to installing GRUB on a software RAID-1? I ask this because most tutorials/help sections seems to ...
2
votes
1answer
252 views

Make Software raid of kernel use dedicated core of cpu

I am sure this is more of a question related to approach than a tech-how-to. I have 2 processors, each with 2 cores on my machine. I have Software RAID (md0) configured using Linux kernel. Is it ...