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Questions tagged [md]

Multiple Device driver aka Linux Software RAID

77 questions
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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…
Andy B
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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…
smammy
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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…
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…
Kolja
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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…
Michael
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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…
Déjà vu
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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.
ensnare
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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…
Robert Siemer
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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…
Amandasaurus
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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,…
RoUS
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(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…
tudor -Reinstate Monica-
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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…
Nathan Neulinger
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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…
Ira
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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…
bardiir
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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…
Cobra_Fast
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