Messages in this thread | | | Date | Sat, 4 Aug 2018 01:20:33 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: [dm-devel] LVM snapshot broke between 4.14 and 4.16 |
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On Fri, Aug 03, 2018 at 03:30:37PM -0400, Mike Snitzer wrote: > > I was trying to give context for the "best to update lvm2 anyway" > disclaimer that was used. Yeah, it was specious.
Well, it seemed to indicate a certain attitude that both Linus and I are concerned about. I tried to use more of a "pursuading" style to impress why that attitude was not ideal/correct. Linus used a much more assertive style (e.g., "Hell, no!").
> And yeah, that isn't a good excuse to ignore it but: dm-snapshot is a > steaming pile as compared to dm thin-provisioning...
On a side note, this is the first that I've heard the assertion that dm-thin was better than dm-snapshot. My impression was that dm-snapshot was a proven code base, that only did one thing and (as far as I could tell) did it well. In contrast, dm-thin is much newer code, **far** more complex, with functionality and corner cases approaching that of a file system --- and just to be even more exciting, it doesn't have an fsck/repair tool to deal with corrupted metadata.
In your opinion, is it because you disagree with the assumption that dm-thin is scary? Or is the argument that dm-snapshot is even scarier?
- Ted
P.S. It could be that my impression is wrong/out-dated, but the kernel documentation still says that userspace tools for checking and repairing the metadata are "under development". As a file system developer, the reaction this inspires is best summed up as:
https://imgflip.com/memetemplate/50971393/Scared-Face
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