Any Reason To Avoid LVM

Carlwill · 2010-12-16 17:55:44

I've been installing Linux for years and have always done just basic ext3/4 partition tables and never tried LVM. I've researched what it is and how it works but I'm wondering if there are any issues with formatting with LVM. Does anyone have any feedback if LVM has some down falls or issues?

Thanks.

Berticus · 2010-12-16 18:09:04

If one hard drive in the logical volume fails, the entire logical volume goes down with it, unless you're mirroring it. Still worth it, IMO.

If you can do hardware RAID though, might as well just go for that.

Carlwill · 2010-12-16 18:11:04

So you're saying LVM is good if I DON'T use software RAID but hardware RAID is good with LVM?

Dieter@be · 2010-12-16 18:45:15

I don't like how with LVM/linux the block layer, device mapper and filesystem are all separate layers.
With ZFS it's one thing, so the block-level code can do optimisations based on application level patterns (zfs will automatically adapt it's data distribution based on load patterns)
I think btrfs has (or will have) things like that as well (to some extent, I don't know what will happen with the block layer code in Linux)

on the topic of raid: btrfs can do "raid"-like setups.
I wouldn't use hardware raid anymore (unless you need high performance parity calculations which you don't want to affect your CPU, but still I would consider it). with hardware raid you're bound to a vendor and to a specific metadata layout on your disks. with softraid, you can use whichever disks and controllers, and the performance bottleneck is usually your disks, not your controller.

Last edited by Dieter@be (2010-12-16 18:48:50)

boogy · 2010-12-16 19:31:25

Personally I use LVM on all my 150 linux servers and never had a problem with it... Its rely perfect ... But I'm rely waiting to see how the new ZFS on linux works. I'm using it on solaris. And I got to say that it's rely rely nice working with it.

Dieter@be · 2010-12-16 20:07:18

oh yeah, another sucky thing about lvm: if you make n COW snapshots, all writes to make up for changes will be done n times. btrfs handles that better (writes are done once, independent of number of snapshots), although i've personally never made more then 1 snapshot at the same time.

ChojinDSL · 2011-03-15 13:34:34

Even if you only have one Harddrive LVM has its advantages. MUCH more flexible partition management.

If you like to split your linux install into separate partitions for /boot / /home /var and such, LVM is a godsend. What I usually do is to create the partitions I want, and give them as little space as necessary, and only grow them when the need arises.

The beauty of LVM means that you can expand your partitions on the fly, while in use. No need to unmount or reboot.

Plus, you can add an extra HD and grow your storage temporarily and then remove that HD again if you have enough space for LVM to move the data.

If your nervous to try it out in a live setup. Just experiment with an external HD. Creating Partitions, resizing them, etc.
Once you get used to the flexibility of LVM, it's kind of hard to go back to the standard rigid partition setup.

fukawi2 · 2011-03-15 22:04:17

The only "issues" I've had are when doing recovery/migration work, it a bit trickier to mount the LVM on another machine (compared to "normal" partitions), particularly when working from images rather than actual block devices. But 'kpartx' has solved this problem

flan_suse · 2011-03-18 15:58:16

I read that if you have an SSD drive, avoid LVM (and even software RAID and encryption) if you want to take advantage of the drive's "Trim" feature. Trim commands cannot be sent past a layer of LVM, software RAID, or encryption/LUKS, even if an ext4 file system sits on top of it all.

Maybe it is different now?

Ramses de Norre · 2011-03-18 16:03:30

ChojinDSL wrote:

The beauty of LVM means that you can expand your partitions on the fly, while in use. No need to unmount or reboot.

But can you also expand the filesystem on the fly?

fukawi2 · 2011-03-19 00:35:03

Ramses de Norre wrote:

But can you also expand the filesystem on the fly?

Depends on the filesystem... ext4 and JFS can, IIRC I think etx3 can.

Arch Linux

#1 2010-12-16 17:55:44

Any Reason To Avoid LVM

#2 2010-12-16 18:09:04

Re: Any Reason To Avoid LVM

#3 2010-12-16 18:11:04

Re: Any Reason To Avoid LVM

#4 2010-12-16 18:45:15

Re: Any Reason To Avoid LVM

#5 2010-12-16 19:31:25

Re: Any Reason To Avoid LVM

#6 2010-12-16 20:07:18

Re: Any Reason To Avoid LVM

#7 2011-03-15 13:34:34

Re: Any Reason To Avoid LVM

#8 2011-03-15 22:04:17

Re: Any Reason To Avoid LVM

#9 2011-03-18 15:58:16

Re: Any Reason To Avoid LVM

#10 2011-03-18 16:03:30

Re: Any Reason To Avoid LVM

#11 2011-03-19 00:35:03

Re: Any Reason To Avoid LVM

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