Questions tagged [device-mapper]

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Data corruption after dmsetup suspend, reload, resume, and re-suspend

Consider the following series of events for a device-mapper crypt target, test, holding an ext4 filesystem. These three commands swap out the crypt target's table with a new (dummy) table. This ...
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2 votes
0 answers
47 views

How to make a virtual disk image out of several parts?

During a process of moving to a virtualized infrastructure I encountered the following curious problem. We want to evaluate everything first. This involves creating a virtual images of all required ...
0 votes
0 answers
11 views

Is devicemapper linear not just passthrough?

I'm trying to follow the script in https://jvns.ca/blog/2021/01/27/day-47--using-device-mapper-to-manage-firecracker-images/?hmsr=joyk.com&utm_source=joyk.com&utm_medium=referral but getting ...
0 votes
0 answers
39 views

Udisks2 rule to ignore BTRFS-in-LUKS array member disks

On Ubuntu 20.04 PC's with a btrfs (in crypto / LUKS) raid-1 disk array, file managers (nautiuls, thunar, etc) show duplicate entries for the [logically] same disk, and repeatedly mount duplicate /...
1 vote
0 answers
119 views

Is it possible to migrate between two physical disks without (much) downtime?

I have a server with a medium-sized database on a disk which is filling-up. There is no LVM or RAID or anything like that in play at this point. I already have the new disk installed in the server. Is ...
0 votes
1 answer
597 views

use mount with LUKS2

Back in times of LUKS1, it was possible to use a command like $ mount /dev/luks-encrypted-partition /mnt/a [enter passphrase upon being prompted] as a shortcut for $ cryptsetup luksOpen /dev/luks-...
0 votes
0 answers
136 views

What are the best practices for device-mapper multipath?

Background: We are setting up the new storage for an HPC Compute cluster for applied statistics, bioinformatics, and genomics. Contrary to our expectations, an active-active configuration did not ...
1 vote
0 answers
17 views

cache_writeback of thin-provisioning-tools running failed

I use Ubuntu 16.04 with kernel 5.4 and thin-provisioning-tools version 0.8.5 I want to test the cache_xml and cache_writeback tools of thin-provisioning, but it failed. It always failed and I don't ...
0 votes
0 answers
474 views

sar -dp reports individual disks higher than their devicemapper logical volume

I am trying to figure out how sysstat is reporting the utilization of the device mapper logical volume, lower than the individual disks that make up the logical volume. I keep trying to do the math ...
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-3 votes
1 answer
327 views

VMWare device mapper size smaller than parition size

I am trying to understand what is going on with my VMWare instance. I have had 50GB partition that I extended to 150GB and resized the partition. However, the partition still shows that it only has ...
  • 887
0 votes
2 answers
354 views

How do you specify how much disk space for each mount point on vsphere?

I created a vm via the vsphere web client. The ESX version is 6.5 and the vsphere version is also 6.5 Via the menu: create virtual machine Option 2f: customize hardware Virtual Hardware: New Hard ...
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1 vote
1 answer
365 views

How to modify the "dm-*" value?

As I command multipath -ll, the output show like this. ocr3 (149455400000000000000000001000000ca0200000d000000) dm-9 IET,VIRTUAL-DISK [size=980M][features=0][hwhandler=0] \_ round-robin 0 [prio=0][...
1 vote
1 answer
350 views

Cannot create PV on /dev/dm-NN (/dev/dm-N works)

I'm unable to create PVs on Multipath-Volumes that are available at /dev/dm-NN where N~[0-9] but I can create them on single digit devices like /dev/dm-9: # pvcreate /dev/dm-6 Physical volume "/dev/...
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2 votes
2 answers
1k views

Why is dmsetup failing when I try to create a snapshot?

I would like to create a COW device for an existing block device using dmsetup. The block device is: # blockdev --getsz /dev/loop0 3534848 I am trying to use a 256M ramdisk as the backing store: # ...
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0 votes
1 answer
161 views

Seeing Multiple Partition for same LUN

Anyone knows why I am seeing multiple device for the same LUN?I checked with storage team they only exposed 360000970000196801239533036304532 for this server but why I am seeing these many partition(...
6 votes
0 answers
6k views

cryptsetup cannot close mapped device

When I run: LANG=C cryptsetup --debug luksClose /dev/mapper/Pool-A it fails as follows: device-mapper: remove ioctl on Pool-A failed: Device or resource busy Device /dev/mapper/Pool-A is still ...
  • 642
11 votes
3 answers
7k views

kvm to vmware migration - lvm based guest + multipathing

What is recommended way of migrate from kvm to vmware in case of lvm based guest with multipathing? I found that similar questions were already asked few years ago: How to migrate KVM based VMs ...
  • 111
10 votes
1 answer
21k views

how to correctly 'extend' a linux device mapper partition?

I am missing some concept with linux disk management, I have free space on a single physical volume that I want to to extend an ext4 file-system with, which is a logical volume. I look at fdisk -l - ...
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0 votes
1 answer
998 views

duplicate entries /dev/mapper

The system is Fedora 23. This occurred after a system upgrade. The issue is duplicate entries in /dev/mapper. As seen by /dev/mapper each partition is represented twice. How can the device based names ...
1 vote
1 answer
928 views

I/O scheduling on LVM on dm-crypt

I have the following setup: Stock Debian stable (Linux kernel 3.16.7) running on Dell PowerEdge R320 Two SATA hard drives in RAID1 on a PERC H310 Mini controller, visible as /dev/sda dm-crypt target ...
1 vote
1 answer
497 views

using same LVM volume for devicemapper and a bind mounted volume

I'm running an Amazon EC2 machine with a 512GB EBS mount. My plan is to split the EBS into two parts - one to be used by Docker 1.11 for its images (via devicemapper) and another to be bind-mounted to ...
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1 vote
0 answers
441 views

Is it possible to extend the data device of an Thin Provision pool setted by device mapper?

TL;DR : How can I extend the Thin-Pool if I'm not using LVM but Device Mapper itself directly? Detailed version: As far as I know, when we create a thin-pool by dmsetup, we can set a ...
3 votes
2 answers
2k views

multipath, device mapper, and disk i/o scheduler

We have two machines with a multi path SAS controller, each with 12 physical disks attached. We were looking into some I/O speed oddness, and noticed that on one machine, where /dev/mpath/mpath*p1 ...
4 votes
0 answers
251 views

How to disable write barrier on docker thinpooldev?

My server has very low disk performance if write barrier is enabled. As it has a disk controller with battery for the cache it is safe to add the "nobarrier" option to /etc/fstab. This makes a huge ...
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1 vote
0 answers
212 views

dmcache - is removing cache device without suspending safe?

I'm using plain dmcache for SSD cache - unmount procedure goes this way: umount fs suspend cache device remove cache device close lvm close LUKS shutdown However sometimes dmsetup doesn't allow me ...
  • 363
11 votes
4 answers
40k views

is /dev/dm-1 a partition or a whole block device?

Is there a way to figure out if /dev/dm-1 is a block device partition or a whole block device? If /dev/dm-1 is a partition, is there a way to find out the path to the corresponding whole block device?
0 votes
0 answers
806 views

Linux, dev-mapper: How to mount a folder with different options than parent folder

I'm using CentOS 7.1 with device-mapper, and /home mounted as /dev/mapper/centos-home on /home type xfs (rw,relatime,seclabel,attr2,inode64,noquota) I'd like to include in fstab an entry for ...
20 votes
1 answer
2k views

Why higher await time for DM multipath device than underlying device?

We have a CentOS 6.4 based server attached to Hitachi HNAS 3080 storage and observed the kernel remount the filesystem in read-only mode: May 16 07:31:03 GNS3-SRV-CMP-001 kernel: [1259725.675814] ...
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14 votes
3 answers
5k views

Linux device-mapper maps LVM PV nested inside LV when taking snapshot

Which is really messing with my plan to back up this machine... I have a server which is a KVM hypervisor to several virtual machines. One of these is running Docker. It has its Docker volumes on /...
2 votes
1 answer
2k views

How to rebuild a dmraid RAID10 array?

Q: How do I force a rebuild? The following describes the scenario. I've been experimenting with forcing a RAID10 to rebuild, so I could see what dmsetup status output should look like when a RAID is ...