Date: Fri, 28 Mar 2014 17:35:39 -0400 From: mikej <mikej@mikej.com> To: <freebsd-fs@freebsd.org> Subject: Re: zfs l2arc warmup Message-ID: <33ff828c517307c9681c361a12cff2ee@mail.mikej.com> In-Reply-To: <alpine.BSF.2.00.1403290116550.60856@woozle.rinet.ru> References: <CAFfb-hpi20062%2BHCrSVhey1hVk9TAcOZAWgHSAP93RSov3sx4A@mail.gmail.com> <CALfReydi_29L5tVe1P-aiFnm_0T4JJt72Z1zKouuj8cjHLKhnw@mail.gmail.com> <CAFfb-hpZos5-d3xo8snU1aVER5u=dSFRx-B-oqjFRTkT83w0Kg@mail.gmail.com> <20140328005911.GA30665@neutralgood.org> <CAFfb-hr=wR6nxqL%2B4tn-y2eQEw4n_g7rZoK9rRLnm_Ldcm1TZQ@mail.gmail.com> <alpine.BSF.2.00.1403290032070.60856@woozle.rinet.ru> <CAOjFWZ7h5080%2BzEvSfzxgENwP%2BPXEXKPXdEDHAtbx5RAxxWT0g@mail.gmail.com> <alpine.BSF.2.00.1403290116550.60856@woozle.rinet.ru>
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On 2014-03-28 17:19, Dmitry Morozovsky wrote: > On Fri, 28 Mar 2014, Freddie Cash wrote: > > [snip most again] > >> Around ZFSv14-ish, the ability to import a pool with a missing ZIL >> was >> added. >> >> Remember the flow of data in ZFS: >> async write request --> TXG --> disk >> sync write request --> ZIL >> \--> TXG --> disk >> >> All sync writes are written to the pool as part of a normal async >> TXG after >> its written sync to the ZIL. And the ZIL is only ever read during >> pool >> import. > > On the other side, doesn't it put the risk on sync-dependent, like > database, > systems? > > I'm thinking not about losing the transaction, but possibly putting > your > filesystem in the middle of (database PoV) transaction, hence render > your DB > inconsistent? > > Quick googling seems to be uncertain about it... As I understand it..... (And I am always looking for an education) Any files system that honors fsync and provided the DB uses fsync should be fine. Any data loss then will only be determined by what transaction (log) capabilities the DB has. --mikej
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