On Thu, Jun 3, 2021 at 3:19 PM Patrick O'Callaghan pocallaghan@gmail.com wrote:
On Thu, 2021-06-03 at 12:51 -0600, Joe Zeff wrote:
On 6/3/21 12:20 PM, Jon LaBadie wrote:
Are old rescue kernels still useful? (6 years?)
They're still just as useful as they were when they were installed. Of course, that means that any function that was added later isn't there, but that doesn't matter because you're only going to use it in emergencies to troubleshoot a broken system.
Surely an old rescue kernel may not be able to mount a BTRFS filesystem?
Not only Btrfs but any file system. A new mkfs may set options that an old kernel doesn't support. There's quite a bit of that in ext4 and XFS land.
If you mkfs.btrfs with today's progs and use defaults, an ancient kernel will mount it. But there are features that old kernels don't support, like for example zstd compression which arrived in kernel 4.14, thus not mountable (incompatible) with older kernels. Free space tree v2 exists since kernel 4.5, but its flag permits ro mount with old kernels.