Questions tagged [software-raid]
322 questions
69
votes
2 answers
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 functionality. In the past, I have used LVM on top of MDRAID,…
Faheem Mitha
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55
votes
5 answers
What's the difference between creating mdadm array using partitions or the whole disks directly
Can someone please explain to me, what the difference is between creating mdadm array using partitions or the whole disks directly? Supposing I intend to use the whole drives.
Imagine a RAID6 created in two ways, either:
mdadm --create /dev/md0…
Vlastimil Burián
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34
votes
3 answers
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 be possible?
It's important because I don't want…
Totor
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30
votes
5 answers
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 functioning correctly.
I'm not sure what happened.
The…
Faheem Mitha
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29
votes
1 answer
grub-install : File descriptor 3 leaked on vgs invocation
I installed Debian Jessie on a LVM in a software RAID 1.
To make sure MBR are written on both disks of the RAID 1, I run dpkg-reconfigure grub-pc (as suggested here) and select both disks.
I get those errors :
root@bouzin:/home/jerome#…
Jérôme
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24
votes
1 answer
What is the bitmap's meaning in mdstat
Not long ago, I have created new Software RAID array (mdadm) with 4 drives in RAID6. It seems to work just fine. mdstat follows:
Personalities : [raid6] [raid5] [raid4]
md0 : active raid6 sda1[0] sde1[3] sdd1[2] sdb1[1]
1953260544 blocks…
Vlastimil Burián
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24
votes
4 answers
How to correctly install GRUB on a soft RAID 1?
In my setup, I have two disks that are each formatted in the following way:
(GPT)
1) 1MB BIOS_BOOT
2) 300MB LINUX_RAID
3) * LINUX_RAID
The boot partitions are mapped in /dev/md0, the rootfs in /dev/md1. md0 is formatted with ext2,…
vic
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23
votes
4 answers
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 disk in the original raid 1 was formatted and…
Adam
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23
votes
5 answers
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 detailed as possible, and I'm really hoping for some…
blitzmann
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19
votes
1 answer
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:
ms:~ #**
I tried to execute raiddev /dev/md0 but…
Özzesh
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18
votes
2 answers
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 out of 4 disks failed. However I don't belive…
stribika
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16
votes
3 answers
How does RAID0 work underneath, when the devices have different sizes?
To my surprise the CentOS 7 installer allowed me to create a RAID0 device consisting of roughly a 17 GB disk and a 26 GB disk. I would've expected that even if it allows that, that the logical size would be 2 * min(17 GB, 26 GB) ~= 34 GB.
Yet I can…
hbogert
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16
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3 answers
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, it uses a new drive letter. Leaving the old one…
Sajan Parikh
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16
votes
1 answer
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 the kernel reports:
$ cat…
maxschlepzig
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12
votes
1 answer
State of LVM raid compared to mdadm
LVM and mdadm / dmraid are both offering software RAID functionality on Linux. This is pretty much a follow-up post to this question from 2014. Back then, @derobert recommends to prefer mdadm over LVM raid for it's matureness - but that was over 4…
LukeLR
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