Date: Fri, 15 Feb 2013 09:08:46 -0600 (CST) From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us> To: Daniel Kalchev <daniel@digsys.bg> Cc: freebsd-fs@freebsd.org, grarpamp <grarpamp@gmail.com> Subject: Re: Crazy ZFS ZIL options: md(4) umass(4) Message-ID: <alpine.GSO.2.01.1302150858470.11141@freddy.simplesystems.org> In-Reply-To: <F053D5FF-0833-4091-9C5D-6A4E10A81CD8@digsys.bg> References: <CAD2Ti2_9i3rj5763UCjzxRw_7%2BqDky1MNRJzdvOZnmdYpLUfYQ@mail.gmail.com> <CA%2BtpaK3wA4kNVzLfE9EDaR1SGLN7_t-N-9Sw%2BvcsdeUKX4EFoA@mail.gmail.com> <CAD2Ti28ZKhrf3Yo06ooL9NXChtSEgvE-Rv_FngY1nfnVwUZ3YQ@mail.gmail.com> <F053D5FF-0833-4091-9C5D-6A4E10A81CD8@digsys.bg>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, 15 Feb 2013, Daniel Kalchev wrote: > Some further clarification. > > ZIL is only read on crash. If you shut down properly etc, the ZIL > will be never read. For most of it's lifetime, the ZIL is write-only > safety net. An insurance, if you wish. Something I did not see mentioned in this discussion thread is that the ZIL is only used for synchronous writes. Database writes and NFS writes are usually synchronous writes. Systems which are not used for these purposes might not produce any synchronous writes and so the ZIL is not used at all. As long as the pool disks obey cache sync requests, the integrity of the pool is assured. The integrity of the pool is not dependent on data in the ZIL. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?alpine.GSO.2.01.1302150858470.11141>