Preamble: I have extensive arrays of drives and due to their irregular sizes, I was using md-linear as a convenient way to manually concatenate arrays of underlying MD (raid5/etc) to manually deal with redundancy. I have probably a few thousand TB in total raw space, and hundreds of TB of actual data and files attached to singular systems. In a recent OS update, I discovered my larger volumes no longer mount because md-linear has been removed entirely from the kernel as of 6.8. I am trying to do rationale archaeology. I sent a note to Mr. Neil Brown who was responsible for the earliest change I found related to this and he suggested I email regressions and linux-raid along with the current maintainers about it. What I've been able to find: In 2604b703b6b3db80e3c75ce472a54dfd0b7bf9f4 (2006) Neil Brown marked a MODULE_ALIAS entry for md-personality-1 as deprecated but it appears the reason was because the form of the personality was changed (not that the underlying md-linear itself was deprecated.) d9d166c2a9d5d01af34396793950aa695883eed4 (2006) reinforced this change via a diff algorithm that overzealously included that line in a diff chunk but which makes annotating prior to it a more manual process. 608f52e30aae7dc8da836e5b7b112d50a2d00e43 (2021) marked md-linear as deprecated in Kconfig, using the rationale that md-linear was deprecated in MODULE_ALIAS—but again which doesn't explain why the *module* was deprecated and appears to me at least to accidentally misconstrue the original reason for the deprecation comment. 849d18e27be9a1253f2318cb4549cc857219d991 (2023) eliminated md-linear entirely, again mostly self-referencing a deprecation notice which was there in actuality for basically multiple decades and seems to have referenced something else entirely. I was hoping you could help me understand why this module was removed? I have found others who also are running into this. Functionality they relied on has disappeared, as per the existence of the following: https://github.com/dougvj/md-linear https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/issues/34 https://bbs.archlinux.org/viewtopic.php?id=294005 (etc) So, it looks like there are many of us who were still using mdadm to manage sub-device concatenation, again in my case for 100s of TB of admittedly casual data storage, and I can't currently find what the actual actual rationale was for removing it. :( For utility's sake, I would like to suggest that linear volumes lessen problems like substriping. I do not think for many of us that shuffling around a few hundred TB is easy to do at any rate. Currently I'm manually re-compiling a fairly heavily-modified md-linear as a user-built module and it seems to work okay. I am definitely not the only one doing this. Please consider resurrecting md-linear. :-) Thank you, Sincerely, at
