2
votes
1answer
15 views

Raid 5 rebuild with wrong stripe size & no failed disks - is data lost?

I'm curious if there are hidden complexities to RAID5 and RAID5 rebuilds. My understanding is that (in a 3 disk array) a rebuild would just directly compute the parity of disks 1 & 2 and write ...
0
votes
0answers
42 views

What are the steps needed to get Redhat/Centos 7 to boot from an mdadm RAID?

I've spent a day on this. Figured it was time to ask. In the end I couldn't get around "Bad magic number in super-block ..." On an average install, my sda exits setup as an EFI. I'm cool with that ...
2
votes
1answer
39 views

Why is so much of my new ext4 filesystem already marked as used?

I have just created a new raid 5 array using 3 4TB drives (aiming for 8TB of space) on an ubuntu system. While I had a few issues getting started, I believe I have set it up correctly and I have ...
1
vote
2answers
24 views

mdadm metadata: should i take precautions to prevent superblock overwrite?

Situation: I'm creating a new RAID1 array using mdadm. I won't be using additional layers, such as LVM or dm-crypt. I've noticed that metadata version 1.2 is now the default. I understand it's the ...
0
votes
1answer
210 views

mdadm raid doesn't mount

I have a raid array defined in /etc/mdadm.conf like this: ARRAY /dev/md0 devices=/dev/sdb6,/dev/sdc6 ARRAY /dev/md1 devices=/dev/sdb7,/dev/sdc7 but when I try to mount them, I get this: # mount ...
0
votes
1answer
25 views

Recovering a (not yet created) RAID5 with URE (Unrecoverable read errors)

I wan't to create a RAID5 array at home, the OS is Linux (Kernel 3.15.7) and the array will be created with mdadm. I wan't to create the array with eigth or ten 1TB discs. Let's assume a single drive ...
2
votes
3answers
66 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 ...
3
votes
1answer
70 views

RAID-1 mirror has become a single hard disk

I have an HP N40L microserver, with 2 identical drives, I used the system to hardware-RAID them as a mirror. I then installed mint on the system about a year ago. This has been running perfectly, ...
1
vote
0answers
21 views

Is it reliable to assemble md from two machines at the same time

Say we have the same disks accessible from two machines. I want to do assembling md from two machines. Is it possible/reliable ? The disks are connected through SAS. All I need to have is reliable ...
0
votes
0answers
47 views

Moved Raid from NAS box to PC running Ubuntu hdparm shows drives frozen

So I had a RAID5 setup in a Partriot S4 Javelin (a NAS box). I'm now migrating it to a proper server running Ubuntu 14.04. NOTE: There are 4 drives. All the drives show up in Ubuntu. Two show ...
2
votes
2answers
34 views

mdadm - exclude drive from monitor

I have created a RAID 1 array with a single drive (in order to add a second drive later). # mdadm --create /dev/md5 --level=1 --raid-devices=2 /dev/sdc1 missing But, I execute /sbin/mdadm --monitor ...
1
vote
1answer
49 views

mixed raid types

I am about to reinitialise my (SW) raid array. Previously the array was raid5 with 4 disks. I've removed one disk in order to install a new additional (larger) drive. What I'd ideally like to do is ...
3
votes
0answers
35 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 ...
2
votes
1answer
60 views

How do I know if software raid is running or setup correctly

This is what I pulled: mdadm --monitor --scan -f --pid-file=/var/run/mdadm/mdadm.pid cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sda1[0] sdb1[1] 262080 blocks super 1.0 [2/2] ...
6
votes
1answer
65 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, ...
1
vote
0answers
179 views

mdadm raid 5 missing partitions after reboot

I had a working raid 5 array that had a whole debian install on it (I set it up during a debian install). I'd been using it a couple of days, all was fine, but since I created it during debian ...
1
vote
0answers
17 views

Linux software raid assembled “itself” with failed drive. Why?

I have two raid1 arrays: md3 (sda3 + sdb3) and md5 (sda5 + sdb5). I deliberately failed the sdb disks because I wanted to change the partition table: # mdadm /dev/md3 --fail /dev/sdb3 # mdadm ...
0
votes
1answer
128 views

Is it useful to setup RAID0 on laptop? [closed]

I have a Dell laptop, which I am going to replace the CD-ROM hub with a HDD. I am thinking if I setup a RAID0 on my original HDD and the new HDD, would I have some I/O performance improvement? ...
0
votes
0answers
46 views

Change Initramfs script

I made RAID 0 by mdadm'ing partition located on dmraid VIA VT6421 and Western Digital hdd. Installed Ubuntu on that RAID. Now, when I boot, I get (initramfs) ash prompt. There, I have to write mdadm ...
0
votes
2answers
117 views

Two arrays have slightly different array size with same size disks/partitions, why?

I created a software RAID 5 array one year ago using mdadm v3.2.x which shipped from CentOS 6.3, after few months, I moved/assembled the array to/in Fedora 19 (now Fedora 20). It had three 3TB disks ...
2
votes
1answer
298 views

Proper way to setup RAID in linux

I have installed Debian 7.4 on a server, and through the installer I setup both RAID and LVM for the drive that the OS is installed on. However, now I want to add two 4TB drives in a RAID-1 array to ...
3
votes
1answer
47 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 ...
4
votes
2answers
326 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 ...
0
votes
1answer
115 views

mdadm large memory consumption [closed]

I am building a RAID 6 with mdadm (8 WD Red 3 Tb) on Ubuntu 13.10x64 server with ext4 filesystem. When I download torrent on the array, server RAM is filled for maximum cap (8 Gb) memory is free when ...
2
votes
1answer
620 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 ...
0
votes
0answers
155 views

Tuning a CentOS VM running on an MDRAID-based XenServer storage repository

I've run out of ideas for tuning disk write speeds on a handful of CentOS VMs running on a lab XenServer 6.2 host. Running under the free license (so vendor support not a concern), the lab host is a ...
1
vote
1answer
258 views

Why is my ext4 filesystem recognizable only on the machine it was formatted on?

Xubuntu liveCD 11.04 running on "bad machine" with mdadm RAID1 array with an unrecognizable ext4 filesystem: To rescue some files, I installed a new hard drive and formatted it to ext4. I copied ...
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 ...
6
votes
1answer
4k 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 ...
3
votes
1answer
289 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
1answer
2k 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 ...
5
votes
2answers
408 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 ...
4
votes
3answers
751 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 ...
2
votes
2answers
295 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 ...
4
votes
1answer
118 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 ...
1
vote
2answers
216 views

Can one use a md-type raid-0 as a drive for zfs pool

I want to play with ZFS at my CentOS. At the moment I have two 750Gb drives and two 400Gb spare drives that I could use. Of course the simplest solution would be to take all of them and use only 400Gb ...
1
vote
2answers
644 views

erased md0, md1 and can't recreate them

I previously had a working RAID 1 array. I think as a result of running grub-install /dev/sdb and grub-install /dev/sdc I somehow wiped my computer of md0 and md1. I need to set them up again. When ...
3
votes
1answer
3k 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 ...
1
vote
1answer
63 views

Can I put 2 disks into a raid-0 array without reformating the FS?

We have an existing /dev/sda disk, we are adding an identical /dev/sdb I want to place these two disks in a raid-0 array. Can I do that without reformating /dev/sda?
2
votes
0answers
356 views

Disable RAID auto detect at runtime

In Linux, I'm partitioning two disks for RAID1 with fdisk. The first disk partitioning succedes, but the second fail because the raid starts automatically and occupy also the second disk (why? it ...
2
votes
3answers
4k 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 ...
4
votes
1answer
811 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 ...
2
votes
1answer
467 views

Ubuntu Software Raid5 - /dev devices changed, will mdadm raid break

I had a major server failure. The OS is fine and back up and running. Before I plug my raid drives back in and try and mount it I need to ask this simple question. The drives that originally mapped ...
13
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 ...
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. ...
2
votes
0answers
299 views

Software raid checksumming slow

On my new 24 disk array I get 900 MB/s of raw read or write using dd to all the disks. When I set the disks up as a 24 disk RAID6 I get 400 MB/s write and 600 MB/s read. It seems to be due to ...
15
votes
3answers
32k 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 ...
5
votes
3answers
4k 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 ...
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
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. ...