Questions tagged [lvm]

In computer storage, Logical Volume Management or LVM provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes.

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195
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6answers
76k views

LVM dangers and caveats

I have recently started using LVM on some servers for hard drives larger than 1 TB. They're useful, expandable and quite easy to install. However, I could not find any data about the dangers and ...
60
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4answers
135k views

How to find the physical volume(s) that hold a logical volume in LVM

I have a volume group (VG) that contains two physical volumes (PV). Several logical volumes (LV) in the VG are likely to use extents on both PVs. Is there a way to tell which LVs occupy space on ...
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3answers
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Is it possible to on-line shrink a EXT4 volume with LVM?

Today I tried this on my machine with OpenSUSE 12.3 (kernel 3.7): # resize2fs /dev/mapper/system-srv 2G resize2fs 1.42.6 (21-Sep-2012) Filesystem at /dev/mapper/system-srv is mounted on /srv; on-line ...
47
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6answers
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What is better LVM on RAID or RAID on LVM?

I currently have LVM on software RAID, but I'd like to ask you what you think it is better solution, maybe some pros and cons? Edit: It is about software raid on lvm or lvm on software raid. I know ...
33
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3answers
72k views

Removing vg and lv after physical drive has been removed

We had a disk fail in a server and replaced it before removing the drive from LVM. The server has 4 physical drives (PV's), each with it's own volume group (VG). Each VG has 2 or more logical ...
33
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4answers
14k views

LVM snapshots vs. file system snapshots

As far as I know, LVM makes it possible to take snapshots of a volume. There are also a number of file systems (ZFS, Btrfs, reiserfs, ...) which supports snapshots. However, I've never understood the ...
29
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2answers
84k views

LV Status: Not available. How to make it available?

I connect an iSCSI target, create a Physical Volume and Volume Group on it. Then I create an LV, and mkfs.ext3 /dev/vg00/vm and all that works great. Then I disconnect the target iscsiadm -m node ...
29
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3answers
23k views

Readahead Settings for LVM, Device-Mapper, Software Raid and Block Devices - what wins?

I've been trying to find a straight answer on this one, and it has proved elusive. This question and its answer is close, but does not really give me the specifics I would like. Let's start with ...
28
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5answers
25k views

LVM Performance overhead?

I would be thankfull if someone who understands how LVM works, could tell me a rough estimate, how much slower using LVM (with a Software RAID1) will be. (What I do not want to know how much slower ...
28
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1answer
6k views

When using software RAID and LVM on Linux, which IO scheduler and readahead settings are honored?

In the case of multiple layers (physical drives -> md -> dm -> lvm), how do the schedulers, readahead settings, and other disk settings interact? Imagine you have several disks (/dev/sda - /dev/sdd) ...
27
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7answers
51k views

How to resize root LVM partition in Fedora without LiveCD or Rebooting

I have a virtual machine that recently had its disk image increased from 20GB to 50GB, and fdisk -l verifies that the VM can see this new size. Now I need to resize my root LVM partition to fill the ...
23
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6answers
28k views

Does LVM need a partition table?

It appears that I am able to successfully do a pvcreate on top of a raw block device, without ever taking the step of creating a partition table. I am then able to create a volume group, logical ...
23
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11answers
36k views

Sync LVM snapshots to backup server

I have a number of Xen virtual machines running on a number of Linux servers. These VMs store their disk images in Linux LVM volumes with device names along the lines of /dev/xenVG/SERVER001OS and so ...
23
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4answers
34k views

KVM/qemu - use LVM volumes directly without image file?

I'm not quite sure how to phrase this question (hence the poor title), so let me provide an example of what I'm trying to do. On my (old) Xen host, I'm able to present LVM filesystems directly to ...
22
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2answers
3k views

Is it safe to mount the same partition to multiple VMs?

I'm using ubuntu 20.04 with Xen Hypervisor. On my machine I have an SSD that hosts my VM images, and then four sata drives which I have data on. My current set up is to mount the data on my domain0 ...
22
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6answers
25k views

How do I easily repair a single unreadable block on a Linux disk?

My Linux system has started throwing SMART errors in the syslog. I tracked it down and believe the problem is a single block on the disk. How do I go about easily getting the disk to reallocate that ...
22
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11answers
95k views

“fdisk -l” like list of partitions and their types for LVM logical volumes?

You know how "fdisk -l" lists drive partition tables and shows the partition id/types for each partition? Is there a similar way to get the partition id for LVM logical volumes? EDIT: I'm aware of "...
22
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12answers
104k views

Can't remove open logical volume

When I try to remove a logical volume I get the message #lvremove /dev/my-volumes/volume-1 Can't remove open logical volume "volume-1" #lvchange -an -v /dev/my-volumes/volume-1 Using logical ...
21
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7answers
7k views

Which filesystem for large LVM of disks (8 TB)?

I have a Linux server with many 2 TB disks, all currently in a LVM resulting in about 10 TB of space. I use all this space on an ext4 partition, and currently have about 8,8 TB of data. Problem is, I ...
20
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4answers
52k views

Is this how LVM snapshots work?

I'm trying to figure out how LVM snapshots work so I can implement it on my fileserver but I'm having difficulty finding anything on google that explains how it works, instead of how to use it for a ...
20
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6answers
14k views

Possible to get SSD TRIM (discard) working on ext4 + LVM + software RAID in Linux?

We use RAID1+0 with md on Linux (currently 2.6.37) to create an md device, then use LVM to provide volume management on top of the device, and then use ext4 as our filesystem on the LVM volume groups. ...
19
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7answers
19k views

Is it possible to convert a Linux box to LVM after the fact?

My Linux server uses LVM because I replace the machine a year ago and installed from scratch. LVM has been a life saver and I love its flexibility. My Linux laptop, however, was last fully installed ...
17
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9answers
29k views

LVM snapshots as a backup strategy

How viable as a backup strategy would be periodical LVM snapshots of xen domU's? Pros, cons, any gotchas? To me it seems like the perfect solution for a fast, brainless restore. Any investigation ...
17
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4answers
130k views

How to display used devices/free space when using LVM?

I have following situation: =$ LC_ALL=C df -hP | column -t Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg0-rootlv 19G 854M 17G 5% / /dev/mapper/vg0-homelv 19G ...
17
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6answers
25k views

Commit or revert a Linux LVM snapshot?

I'm about to perform an experimental upgrade on my CentOS 5 server. If the upgrade fails, I want to be able to back out the changes to the filesystem. This scenario seems similar to the example in ...
17
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7answers
41k views

How can I map iostat device names to LVM /dev/mapper/XXX names?

mount shows mount devices like: /dev/mapper/VolGroup01-LogVol00 on /var type ext3 (rw) or /dev/mapper/VolGrp_backups-backups on /mnt/backups type ext3 (rw) but iostat uses dm- notation. like dm-0,...
17
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7answers
22k views

Do you lose everything when you have a hard disk failure in a multi-hard disk LVM that does NOT use RAID?

I'm debating about using LVM for a media/file server because I would like to combine multiple physical hard disks into one volume. I do not wish to use any RAID in my LVM so my question is: If one ...
17
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4answers
24k views

How to keep or drop LVM snapshot?

I have made an LVM snapshop by lvcreate --name snap --size 10G -s /dev/vg00/vm What command should I write if I want to drop the snapshot, and not keep the changes that have happened since the ...
16
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7answers
168k views

How to extend a Linux PV partition online after virtual disk growth

VMware allows to extend the size of a virtual disk online - when the VM is running. The next expected steps for Linux system are: extend the partition: delete and create a larger one with fdisk ...
16
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8answers
2k views

Optimal UNIX File System Partition + Setup Strategy

When partitioning a new system disk(s) for UNIX, what is your prefered strategy for both desktop and/or servers? Please include disk partition layout, file system format(s) and options, mount points, ...
16
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2answers
51k views

How to remove bad disk from LVM2 with the less data loss on other PVs?

I had a LVM2 volume with two disks. The larger disk became corrupt, so I cant pvmove. What is the best way to remove it from the group to save the most data from the other disk? Here is my pvdisplay ...
15
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5answers
25k views

Is online disk resize possible with KVM?

We're evaluting KVM for Linux virtualization on a few projects. All is going well so far. But one of our requirements is the ability to add disk space to a running guest without rebooting or taking it ...
15
votes
1answer
13k views

Resizing a LUKS encrypted volume

I have a 500GiB ext4 filesystem on top of LUKS on top of an LVM LV. I want to resize the LV to 100GiB. I know how to resize ext4 on top of an LVM LV, but how do I deal with the LUKS volume? mgorven@...
15
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2answers
18k views

SSD, Erase Block Size & LVM: PV on raw device, Alignment

I want to install a new SSD and use the the whole device as a PV for LVM - in other words: i don't plan to put even one partition on this device. So aligning partitions on the erase blocks is not ...
14
votes
6answers
37k views

Moving a Logical Volume directly from one server to another over the network?

I have a KVM host machine with several VMs on it. Each VM uses a Logical Volume on the host. I need to copy the LVs to another host machine. Normally, I would use something like: dd if=/the/logical-...
14
votes
4answers
7k views

Improving IO with FlashCache

I have a server with 2 HDD's (2x 1 TB), running in RAID 1 (SW-RAID). I want to improve IO performance by using flashcache. There are running KVM virtual machines on it, using LVM. Regarding this, I ...
14
votes
3answers
4k 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 /...
13
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4answers
37k views

How to mount virtual machine's LVM partition on KVM host?

If I trying to do following on KVM host: # kpartx -av /dev/VolGroup00/kvm101_img add map kvm101_img1 : 0 208782 linear /dev/VolGroup00/kvm101_img 63 add map kvm101_img2 : 0 125612235 linear /dev/...
13
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5answers
11k views

LVM and disaster recovery

I understand what LVM is and what it accomplishes, but I feel like I am missing some things. Lets say we have two physical drives, sda and sdb. Both are 100 Megs. I put them into VolumeGroup1 and ...
13
votes
1answer
26k views

Logical volume attributes

I've used lxc-clone command to clone my lvm-based container (test_lvm was copied to create u33). Container works fine, but the output of sudo lvs confuses me: LV VG ...
12
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5answers
15k views

What are the benefits of the Logical Volume Manager [closed]

What are the features and potential benefits of Logical Volume Manager beyond what is detailed on its Wikipedia page?
12
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5answers
32k views

How to recover logical volume deleted with lvremove

I am on CentOS 5.5 and am running Xen. I have a large volume group that I create logical volumes on using lvcreate. Today I had a customer cancel her account, then change her mind about an hour ...
12
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4answers
16k views

is it possible to simultaneously mount 2 LVM volumes that are exact copies of each other (same UUIDs)?

I have cloned (using dd) the hard drive in a live system onto several multiple backup hard drives. The root partition in the live system is a LVM volume. The backup copies are intended to be drop-in ...
12
votes
5answers
24k views

linux LVM mirror vs. MD mirror

I think I remember making some mirrors years ago with LVM, and I don't remember this "log" thing. Or maybe I made the mirror with mdadm and put LVM on top. That must be it. What is the LVM log for if ...
12
votes
2answers
14k views

How to do the equivalent of Synology Hybrid Raid on Linux myself?

http://forum.synology.com/wiki/index.php/What_is_Synology_Hybrid_RAID%3F Synology is just Linux and uses LVM. How do their tools automate LVM to achieve what they call their Hybrid Raid?
12
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3answers
8k views

LVM volume group shared between KVM/libvirt host and guests: is this a bad idea?

I have just built a shiny new KVM/libvirt-based virtual machine host, containing 4 SATA II hard drives, and running CentOS 5.5 x86_64. I have decided to create virtual machine disks as logical ...
11
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4answers
28k views

What is the difference between LVM and LUN

Both seem to be a virtualization layer on top of physical disks. I'm having a hard-time understanding each of them and the difference between them.
11
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5answers
42k views

How to change a physical partition system to LVM?

I have a server with Debian that have 3 physical partitions covering all the disk: boot, root y swap. Now I want to replace that partitions with LVM partitions. I know how install Debian with LVM at ...
11
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3answers
25k views

What KVM disk type to use?

I'm setting up a few KVM virtual guests and I'm debating which disk type to use. I haven't been able to find a good resource online that runs down the pros and cons of each. Can you help me create a ...
11
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6answers
23k views

How to access LVM partitions on OS X?

I need to access ext3 partitions over an LVM logical volume in a SATA HD connected through USB2 to my iMac with OS X 10.6 . Is it possible to see LVM volumes from OS X? How? Disk Utility says that ...

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