I love all of the work you guys do @dm-devel . Thanks for taking the time to read this.
I would like to use thin provisioning targets in production, but it's hard to ignore the warning in the documentation. It seems like, with an understanding of how thin provisioning works, it should be safe to use.
"These targets are very much still in the EXPERIMENTAL state. Please do not yet rely on them in production. But do experiment and offer us feedback. Different use cases will have different performance characteristics, for example due to fragmentation of the data volume."
I believe that similar suggestions have been in place for more than 7 years now, based on this post: https://www.redhat.com/archives/dm-devel/2011-July/msg00012.html
Is it still the case that thin provisioning should never be used in production? There are plenty of articles online (including from redhat) which make no mention of the fact that the underlying technology is unsafe. LVM does not offer any warnings about the inherit risk of using thin provisioning.
Is that advisory still necessary? If so, can you provide some insight specifically into what is unsafe about the thin targets at this point? Is the concern that the underlying software device drivers are still not tested well enough to avoid bugs? Is this more a situation where someone might run into extremely poor performance for a very bad implementation of the targets? Is it more about people directly using the targets instead of using LVM, and maybe it's not bullet-proof for bad integrations?
If the metadata and data device for the thin pool have enough space and are both error free, the kernel has plenty of free RAM, block sizes are set large enough to never run into performance issues (64 MiB), all of the underlying hardware is redundant on high performance NVME (no worries of fragmentation of data volume)... is it still unsafe for production? If so, can you shed some light on why that is?
Thin provisioning is so cool. It would be a shame to not use it!
Thank you so much!
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