Date: Fri, 15 Feb 2013 01:16:12 -0800 From: Xin LI <delphij@gmail.com> To: grarpamp <grarpamp@gmail.com> Cc: freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: Crazy ZFS ZIL options: md(4) umass(4) Message-ID: <CAGMYy3ugPBY1aME0rhMBjLJ3iZgh7W--xSqAOa7Gg1%2B3_Zv9Lg@mail.gmail.com> In-Reply-To: <CAD2Ti2_9i3rj5763UCjzxRw_7%2BqDky1MNRJzdvOZnmdYpLUfYQ@mail.gmail.com> References: <CAD2Ti2_9i3rj5763UCjzxRw_7%2BqDky1MNRJzdvOZnmdYpLUfYQ@mail.gmail.com>
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On Fri, Feb 15, 2013 at 1:00 AM, grarpamp <grarpamp@gmail.com> wrote: > I have thousands of small files being written most under 8KiB, they > either end up being removed or combined in various ways to > produce a set of data that is stored long term. I also have > tens of 10-50MiB files similarly, but rarely. It's not fully clear > to me the benefits of a split ZIL. Some say a split ZIL will ward > off some fragmentation, which pushing over 80% I'm sure to see > otherwise. Plus a speed boost if on faster media. And maybe > even no need to commit some ZIL to disk as small files are > removed before ZFS decides to aggregate? > > Anyway, use case aside, I can put 1GiB of ram as ZIL.Same for 32GiB USB. > RAM is obviously fast and power fail prone. > USB is slow and power safe. > Either could be mirrored, 2xRAM, 2xUSB. > > - If I lose power on RAM, will the disk still be consistent? > - What data integrity does ZIL have? None? ZFS dataset's sha256? > - Any production experiences with this crazy ideas? Why don't just set sync=disabled? Cheers, -- Xin LI <delphij@delphij.net> https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die
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