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mdraid in weird state after failed rebuild

So my NAS (mdraid level5) mainboard died and I built a new system - there I reassembled the raid and the rebuild started: md0 : active raid5 sde4[3] sdc4[0] sdd4[2] sdb4[4] 8634123072 blocks level 5,...
Funky Luke's user avatar
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1 answer
67 views

Is it safe to use device name such as sda to create md and ZFS RAID array?

In md we can scan or assemble an array using UUID: mdadm --assemble "/dev/md/raid5" --uuid "b9a09187:a1ac838f:b4e90395:d6293c19" And in ZFS, we have a service for that purpose: rc-...
Livy's user avatar
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1 vote
0 answers
94 views

`md(4)` command turns screen on when it starts or stops checking the arrays

Every time md (or is it mdcheck?) performs a RAID check or pauses/continues it, the screen of my device turns on. These are the relevant syslog entries, the screen turned on at 6:15: Jul 4 06:11:25 ...
Daniel F's user avatar
  • 887
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1 answer
2k views

slow access/reads of linux md raid1 array

I have a Linux md-raid raid1 array (ext4 fs), with 2 3TB disks. The array has been showing significant slowness in access and read times over the last few months. Doing an ls on a directory w/ less ...
baronmog's user avatar
0 votes
0 answers
1k views

How to debug frozen md raid?

We have an old backup server with lots of disks and one mount with md raid 5 setup has now frozen. How to diagnose the problem and get it to running again? I would like to avoid restarting the whole ...
Mikko Rantalainen's user avatar
0 votes
1 answer
44 views

Recovering failed RAID5

md0 : active raid5 sdc2[5](S) sda2[4] sdd2[3](F) sdb2[1] 17510688768 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/2] [UU__] What happend: sdc failed I have repleaced it with a new HDD ...
zephyr.b6's user avatar
2 votes
1 answer
239 views

What should I expect to see if md/linux RAID is properly compensating for a failing drive?

Does the md subsystem output any messages (to syslog/systemd-journal) to indicate that it's running in a degraded state (or anything else that might indicate that it has successfully reacted to a ...
jhfrontz's user avatar
  • 359
9 votes
2 answers
7k views

MD device name changing to include "HOSTNAME:" after first reboot. How do I get a consistent name?

On Ubuntu 18.04 I create a RAID 1 array like this: mdadm --create /dev/md/myarray --level=1 --run --raid-devices=2 /dev/sdc /dev/sdd I then add the output of mdadm --detail --scan /dev/md/myarray to ...
EM0's user avatar
  • 476
5 votes
1 answer
1k views

What are data integrity / bit-rot protection options on CentOS 7?

I have a 2 disk CentOS 7 machine build that I need data integrity / bitrot protection on. How can I achieve this? Note from my reading btrfs,zfs and DM-Integrity does not seem to be options. Btrfs ...
MeData's user avatar
  • 61
1 vote
1 answer
80 views

convert a md file in odt with correct name

I added this command in Dolphin menu for convert a .md (Mark Down) file to .odt (Open Document Text ) file: pandoc %U -o %F.odt and I get the right file, but with two extension: fileorig.md.odt ...
Duns's user avatar
  • 111
3 votes
1 answer
2k views

linux "mdadm --write-journal" and lvmcache - how do they relate?

In linux mdadm man page I saw the option "--write-journal". How does this relate to lvmcache as lvmcache is built on top of dm-cache? Are they different things or does lvmcache do something like "--...
user220574's user avatar
0 votes
0 answers
614 views

RAID1 resync doesn't keep syncronized disks when one device was manually changed

After some crash on a RAID1 I did some investigation and tests. Doing the following: # dd if=/dev/zero of=1 bs=1M count=256 # dd if=/dev/zero of=2 bs=1M count=256 # losetup /dev/loop1 1 # losetup /...
Emilio Lazo's user avatar
2 votes
1 answer
22k views

How to wipe md raid meta?

I have Ubuntu 16.04 host with 3 Ubuntu 17.10 guests in KVM (Virtual Machine Manager 1.3.2). I export several block devices from 2 guests to the other guest (let's call it frontend) via iSCSI portal ...
ikudyk's user avatar
  • 83
2 votes
1 answer
4k views

EFI system partition on top of MD RAID and LVM

I'd like to put a EFI system partition on top of a MD RAID 1 + LVM setup. So the ESP would be a Logical Volume on top of the MD RAID device. I've heard mixed things about whether this is possible. Has ...
Faheem Mitha's user avatar
  • 35.3k
1 vote
0 answers
469 views

Tried to grow my raid6 array with a new drive, got "Failed to restore critical section"

I added a new drive to my RAID6 array, before I added the drive my array looked like this $ cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md0 : active raid6 sde[5] sdc[1] sdb[6] sdf[4] ...
Azelphur's user avatar
1 vote
1 answer
2k views

Recover from raid-5 to raid-6 reshape and crash, mdadm reports 0K/sec rebuild

I have a question similar to older thread but I'm not stuck with 100 % CPU usage. I added one more disk (sdd1) to my 5x3TB raid-5 array and upgraded it to raid-6 which all went well until the power ...
winny's user avatar
  • 147
1 vote
1 answer
138 views

Can I recover filenames from a failed RAID0 (Linux Debian 5.0.8)

Linux Debian version 5.0.8 is running on my Iomega NAS and it has a RAID0 array of four 3TB disks that failed on the "third" disk. I am aware of the non-redundancy of RAID0 but I would like to ...
Michel Dubois's user avatar
8 votes
1 answer
1k views

md raid5: translate md internal sector numbers to offsets

TL;DR summary: Translate an md sector number into offsets(s) within the /dev/mdX device, and how to investigate it with xfs_db. The sector number is from sh->sector in linux/drivers/md/raid5.c:...
Peter Cordes's user avatar
  • 6,486
2 votes
0 answers
958 views

MD RAID 5 module doesn't load at boot

I recently upgraded my NAS to kernel 4.4 and now my md raid 5 array doesn't assemble itself at boot. dmesg reveals this: [ 2.299666] md: personality for level 5 is not loaded! and doing lsmod | ...
Scoopta's user avatar
  • 1,630
5 votes
3 answers
23k views

Command 'pvs' says PV device not found, but LVs are mapped and mounted

I had problem with my system (faulty internal power cable). When I got the system back up and running, arrays rebuilding, etc, I seem to have a situation where the pvs command (and vgs and lvs) ...
StarNamer's user avatar
  • 3,192
1 vote
1 answer
1k views

What are the overheads of using multiple smaller raid devices versus partitioned raid devices as physical volumes?

LVM only allows volume groups to be expanded by adding physical volumes. So if I have multiple volume groups which may need extra space, but it can't be predicted which will expand fastest, it's best ...
StarNamer's user avatar
  • 3,192
70 votes
2 answers
87k views

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 ...
Faheem Mitha's user avatar
  • 35.3k
1 vote
0 answers
39 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 ...
Kostiantyn Ponomarenko's user avatar
2 votes
0 answers
165 views

MD soft-raid to replace fake raid: How to get rid of old metadata?

I had a system running with fake RAID (Intel controller, imsm), which had some problems. Now I'm switching to the regular MD soft-RAID - I created a RAID 1 on /dev/sda1 and /dev/sdb1. Seems to work ...
trapperjohn's user avatar
3 votes
2 answers
2k views

Very poor read performance compared to write performance on md(raid1) / crypt(luks) / lvm

I'm experiencing very poor read performance over raid1/crypt/lvm. In the same time, write speeds are about 2x+ faster on the same setup. On another raid1 setup on the same machine I get normal read ...
user avatar
20 votes
3 answers
23k views

Linux md RAID: /dev/md0 vs. /dev/md/0

On newer systems /usr/share/mdadm/mkconf (the script that is used to generate /etc/mdadm/mdadm.conf) tends to use the device name /dev/md/0 instead of /dev/md0: new-system ~ # /usr/share/mdadm/mkconf ...
Martin von Wittich's user avatar
2 votes
1 answer
176 views

Same file with different content on every read [closed]

I have a problem with a filesystem here on a storage machine. We noticed, that many of the data that comes out of the systems seams to be corrupt, but only with minor problems like CRC errors with ...
a4c8b's user avatar
  • 121
6 votes
1 answer
746 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 ...
zje's user avatar
  • 2,311
5 votes
2 answers
5k 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 ...
Totor's user avatar
  • 20.3k