[developer] Re: [zfs] Re: April OpenZFS Leadership Meeting

[Igor Kozhukhov]

> 
> For anecdotal experience regarding root pool compression, the issue was there with older GRUB loader of OpenSolaris and contemporary Solaris 10; I believe it was fixed in the illumos branch after the fork (can't find and point to a commit now, possibly soon after lz4 introduction; no idea about state of later Solaris releases).
> 
> The problem manifested by GRUB refusing to read datasets (rpool, rpool/ROOT, rpool/ROOT/$BENAME) that had the compression enabled (even if no blocks were in fact compressed) or disabled at the moment but compressed blocks encountered during a read.
> 
> This was one of main reasons early on for my split-root support scripts, so /usr could be separated into a gzip-9'ed dataset and shrink from ~3gb to ~1gb on a default install.
> 
> On my current laptop I see rpool has compression=off, rpool/ROOT has lz4 and rootfs(es) inherit that. Works well WRT stability and performance.

it is known issue with compression=on on rpool, but it is know working scenario for compression=on rpool/ROOT as dataset with root fs - it is working fine on Intel and SPARC
it is why i tried to explain to: do not use compression=on on pool itself , but use it on dataset where root file system available = rpool/ROOT and inherit to BE in rpool/ROOT/*.

but my English is not good in this context.

-Igor

> 
> Hope this helps,
> Jim
> 
> --
> Typos courtesy of K-9 Mail on my Android
> 
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