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Questions tagged [md]

The tag has no usage guidance.

2
votes
1answer
47 views

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

I have a 2 disk CentOS 7 machine build that 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. ...
0
votes
1answer
32 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 ...
1
vote
1answer
126 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 "--...
-1
votes
0answers
7 views

MDRAID refusing to reassemble RAID1 disk — claims no superblock on either disk

I've got a pair of 5TB disks, both known good, set up as a mirrored set. Every time the server reboots, MD fails to reassemble the RAID. Using mdadm --assemble says there's no superblock on the ...
0
votes
0answers
154 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 /...
2
votes
1answer
1k 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 ...
2
votes
0answers
42 views

Why does my /home partition not get automounted?

I have a problem which I don't understand. It's always necessary to make a sudo mount -a before I can log in successfully. How do I manage to mount /home before logging in? Here's my setup: #/etc/...
1
vote
1answer
1k 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 ...
1
vote
0answers
146 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] ...
1
vote
1answer
89 views

Find matching MD5 and XML in a directory

Do you know what bash script I can use to search or find out if a directory has both MD5 and XML? The issue is some users sometimes forget to send both MD5 and XML. If one file is missing in a ...
1
vote
1answer
497 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 ...
1
vote
1answer
50 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 ...
9
votes
1answer
460 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:...
2
votes
0answers
403 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 | ...
4
votes
3answers
13k 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) ...
1
vote
1answer
728 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 ...
41
votes
2answers
47k 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 ...
1
vote
0answers
30 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 ...
2
votes
0answers
136 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 ...
2
votes
2answers
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 ...
14
votes
3answers
12k 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 ...
2
votes
1answer
131 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 ...
6
votes
1answer
646 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 ...
6
votes
2answers
3k 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 ...