Multiple Device driver aka Linux Software RAID
Questions tagged [md]
77 questions
2
votes
1 answer
Various problems with software raid1 array built with Samsung 840 Pro SSDs
I am bringing to ServerFault a problem that is tormenting me for 6+ months. I have a CentOS 6 (64bit) server with an md software raid-1 array with 2 x Samsung 840 Pro SSDs (512GB).
Problems:
Serious write speed problems:
root [~]# time dd…
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Andy B
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2
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1 answer
Reshape linux md raid5 that is already being reshaped?
I just converted my RAID1 array to a RAID5 array and added a third disk to it. I'd like to add a fourth disk without waiting fourteen hours for the first reshape to complete.
I just did this:
mdadm /dev/md0 --add /dev/sdf1
mdadm --grow /dev/md0…
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smammy
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2
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1 answer
Backup data from RAID 1 disk out of its server
I'm facing with a pretty easy problem in my opinion.
I've extracted a working disk from a RAID1 and I'm looking to copy only data (FS and RAID configuration doesn't matter) into another location (another FS).
My problem is I'm not able to mount…
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Doomsday
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MD Raid can't be assembled
I was running a Raid5 with 3 disks at on my homeserver. But had some problems with the back-plane for the disks. The disks weren't detected reliable. So I replaced the back plane and the disks are now detected correct. But the Md array is weird…
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Kolja
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votes
2 answers
Move an existing RAID 5 array from Ubuntu to Gentoo
I have a 64-bit Ubuntu machine with a 4-disk RAID 5 using software raid (md). I've been able to boot an Ubuntu LiveCD and recognize the array with a simple mdadm -A /dev/md0. It was easy to mount after that and nothing had to rebuild.
I'm installing…
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Michael
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3 answers
Linux boot: md raid FS not ready (sometimes)
Using Ubuntu 11.04 (latest patched)
I have 5 RAID-1 file systems that are automatically assembled during the boot process
(Note: none of the system FS /, /usr... are raid, only user FSes).
Once in a while, during boot, an MD cannot be assembled…
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Déjà vu
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1 answer
Linux software RAID that uses system RAM for write cache
Is it possible to configure software RAID 5 on linux that uses system RAM for write cache? I have a file server with 8GB of RAM ... would be really cool if I could dedicate 4GB to write cache. If so, how is this done? Thanks.
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ensnare
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1 answer
How does Linux MD software RAID avoid assembling old and new devices into the same array?
On a Linux MD software RAID1 I removed a failed drive and added a new one. (All fine now.) The old drive and the new were never in the system at the same time.
Do I see that right, that adding the old drive to the system (for examination) will not…
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Robert Siemer
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2 answers
2 disk raid0, move all data to one disk, so the other can be removed
I have a raid0 md disk made up of 2 equalized disks. I would like to remove & replace one of the disks (with a disk of the same capacity), without losing any data. Since the md filesystem is only 42% full, all the data should fit on one of the…
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Amandasaurus
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0 answers
Dismounting MD RAID1 LUKS-encrypted volume with partitions
Fedora 29. I created a 5TB RAID1 volume using mdadm. I then encrypted the volume with cryptsetup luksFormat. I then created ext4 partitions on the encrypted volume. (I did it this way so I can add disks to the RAID1 array, wait for them to sync,…
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RoUS
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vote
1 answer
(Why) Does lvmraid6 need 5 drives?
I'm investigating using LVMRAID instead of MD+LVM. In my case, I'm looking at a RAID6.
As expected, the docs say you need N+1 devices for RAID5, and a minimum of 3 drives.
The docs say for RAID 6 you need N+2.
However, it then says that the…
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tudor -Reinstate Monica-
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1 answer
How to pre-emptively repair/replace drive in linux md array without going degraded first?
I have (had, it's already been swapped out, asking this for future use) a drive that is indicating pending failure with internal SMART tests and bad block remaps.
It is straightforward to mdadm --fail the soon to be bad drive and rebuild to a hot…
![](../../users/profiles/85986.webp)
Nathan Neulinger
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vote
1 answer
Teaming a drive in multiple RAID groups
I've setup a home RAID for a friend in the past from a heap of old and new 2T and 3T drives. seems very much like what BeyondRAID does. I made a 7 member RAID5 group of the 2T volumes and the first 2TiB of the 3T drives, and a second 5 member group…
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Ira
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2 answers
md raid fails to boot with missing drive
I got a server with Debian Jessie, 4 Drives sda to sdd all of which are partitioned likewise. The system is in a raid1 md raid over all drives. All drives do have grub and I can swap discs with each other, each one is bootable and the system boots…
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bardiir
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1 answer
How to keep md-raid from blocking IO?
I run a server with md-raid (software) level 1 (2 HDDs mirroring) and several different applications run on it.
The problem arises when file-intensive jobs (e.g. extracting large archives) run while some users are also using realtime applications…
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Cobra_Fast
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