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krt

Member

Registered: 2026-03-23

Posts: 1  

linear arrays

Is there any particular reason the linear array option isn't being compiled at least as a kernel module by default?  I believe its primary use case is for backups, where in a two disk example, one would want as much data preserved on at least one disk in the event another disk fails, not have half the data as in raid0, etc, or half the capacity as in raid1.  (these are disk sets where they're mounted, written to, unmounted and removed offsite for safe keeping and recovery purposes)

Basically, having to compile the linear module on Excalibur requires downloading the kernel, making sure I have the write packages to build a kernel, and doing the kernel build routine.  This works, but its not what I want to have to do in the future to build a box to get the backups restored, where i'm presuming if that situation ever does arise, I wont be in much of a mood to watch a kernel compile.  Naively said, I think this could be solved by marking the linear code as a module in the default config and including it as a compiled module that's installed with the other modules.

thanks for reading this far and considering the plight of a linear array user.

lynch9

Member

Registered: 2024-07-17

Posts: 35  

Re: linear arrays

Most admins today prefer LVM as it is more flexible

kernel maintainers are optimizing for less surface area and most common use cases. I would say MD linear fails in both

Why don't you build just the module, though?

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ralph.ronnquist

Administrator

From: Battery Point, Tasmania, AUS

Registered: 2016-11-30

Posts: 1,629  

Re: linear arrays

Do you have a reference on the "most admins" statistic?

Isn't LVM just an abstraction over the device mapper?

And why mention LVM as if it was an alternative to raid? Aren't they two independent concerns?

Andre4freedom

Member

Registered: 2017-11-15

Posts: 257  

Re: linear arrays

md:       

md - Multiple Device driver aka Linux Software RAID

supports:

md supports RAID levels 1 (mirroring), 4 (striped array with parity de‐
       vice),  5  (striped  array  with  distributed  parity  information),  6
       (striped array with distributed dual redundancy  information),  and  10
       (striped  and  mirrored).

which is the base to create software-arrays (kernel)

LVM2: is very useful to make an abstraction of disk-space to rend volumes flexible.

Both work best together.
I use that on servers (Devuan 5 Daedalus) and it still exists the same way in Devuan 6 Excalibur.
As it exists in most Linux distros, btw.

The manual pages are very instructive.

Last edited by Andre4freedom (Yesterday 09:07:14)

lynch9

Member

Registered: 2024-07-17

Posts: 35  

Re: linear arrays

My point was about operational overlap, not architectural equivalence.

In the specific case of linear aggregation, LVM is often used in practice instead of MD linear because it achieves the same end result (concatenation) while offering additional flexibility

“most admins” was shorthand for a general trend, not a statistical claim lol sorry about the imprecision

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