Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On 06/05/2010 21:45, Nicolas Williams wrote: On Thu, May 06, 2010 at 03:30:05PM -0500, Wes Felter wrote: On 5/6/10 5:28 AM, Robert Milkowski wrote: sync=disabled Synchronous requests are disabled. File system transactions only commit to stable storage on the next DMU transaction group commit which can be many seconds. Is there a way (short of DTrace) to write() some data and get notified when the corresponding txg is committed? Think of it as a poor man's group commit. fsync(2) is it. Of course, if you disable sync writes then there's no way to find out for sure. If you need to know when a write is durable, then don't disable sync writes. Nico There is one way - issue a sync(2) - even with sync=disabled it will sync all filesystems and then return. Another workaround would be to create a snapshot... However I agree with Nico - if you don't need sync=disabled then don't use it. Someone else mentioned that yet another option like sync=fsync-only would be useful so all would be async but fsync() - but frankly I'm not convinced as it would require a support in your application but at this point you already have a full control of the behavior without need for sync=disabled. -- Robert Milkowski http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On Thu, May 06, 2010 at 03:30:05PM -0500, Wes Felter wrote: > On 5/6/10 5:28 AM, Robert Milkowski wrote: > > >sync=disabled > >Synchronous requests are disabled. File system transactions > >only commit to stable storage on the next DMU transaction group > >commit which can be many seconds. > > Is there a way (short of DTrace) to write() some data and get > notified when the corresponding txg is committed? Think of it as a > poor man's group commit. fsync(2) is it. Of course, if you disable sync writes then there's no way to find out for sure. If you need to know when a write is durable, then don't disable sync writes. Nico -- ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On 5/6/10 5:28 AM, Robert Milkowski wrote: sync=disabled Synchronous requests are disabled. File system transactions only commit to stable storage on the next DMU transaction group commit which can be many seconds. Is there a way (short of DTrace) to write() some data and get notified when the corresponding txg is committed? Think of it as a poor man's group commit. Wes Felter ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On Thu, May 06, 2010 at 01:15:41PM +0100, Robert Milkowski wrote: > On 06/05/2010 13:12, Robert Milkowski wrote: > >On 06/05/2010 12:24, Pawel Jakub Dawidek wrote: > >>I read that this property is not inherited and I can't see why. > >>If what I read is up-to-date, could you tell why? > > > >It is inherited. Sorry for the confusion but there was a discussion if > >it should or should not be inherited, then we propose that it > >shouldn't but it was changed again during a PSARC review that it should. > > > >And I did a copy'n'paste here. > > > >Again, sorry for the confusion. > > > Well, actually I did copy'n'paste a proper page as it doesn't say > anything about inheritance. > > Nevertheless, yes it is inherited. Yes, your e-mail didn't mention that and I wanted to clarify if what I read in PSARC changed or not. Thanks:) -- Pawel Jakub Dawidek http://www.wheelsystems.com p...@freebsd.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! pgp3bNocGiTgs.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On 06/05/2010 13:12, Robert Milkowski wrote: On 06/05/2010 12:24, Pawel Jakub Dawidek wrote: I read that this property is not inherited and I can't see why. If what I read is up-to-date, could you tell why? It is inherited. Sorry for the confusion but there was a discussion if it should or should not be inherited, then we propose that it shouldn't but it was changed again during a PSARC review that it should. And I did a copy'n'paste here. Again, sorry for the confusion. Well, actually I did copy'n'paste a proper page as it doesn't say anything about inheritance. Nevertheless, yes it is inherited. -- Robert Milkowski http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On 06/05/2010 12:24, Pawel Jakub Dawidek wrote: I read that this property is not inherited and I can't see why. If what I read is up-to-date, could you tell why? It is inherited. Sorry for the confusion but there was a discussion if it should or should not be inherited, then we propose that it shouldn't but it was changed again during a PSARC review that it should. And I did a copy'n'paste here. Again, sorry for the confusion. -- Robert Milkowski http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On 06/05/2010 12:24, Pawel Jakub Dawidek wrote: I read that this property is not inherited and I can't see why. If what I read is up-to-date, could you tell why? It is inherited, this changed as a result of the PSARC review. -- Darren J Moffat ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Heads Up: zil_disable has expired, ceased to be, ...
On Thu, May 06, 2010 at 11:28:37AM +0100, Robert Milkowski wrote: > With the put back of: > > [PSARC/2010/108] zil synchronicity > > zfs datasets now have a new 'sync' property to control synchronous > behaviour. > The zil_disable tunable to turn synchronous requests into asynchronous > requests (disable the ZIL) has been removed. For systems that use that > switch on upgrade > you will now see a message on booting: > > sorry, variable 'zil_disable' is not defined in the 'zfs' module > > Please update your system to use the new sync property. > Here is a summary of the property: > > --- > > The options and semantics for the zfs sync property: > > sync=standard >This is the default option. Synchronous file system transactions >(fsync, O_DSYNC, O_SYNC, etc) are written out (to the intent log) >and then secondly all devices written are flushed to ensure >the data is stable (not cached by device controllers). > > sync=always >For the ultra-cautious, every file system transaction is >written and flushed to stable storage by system call return. >This obviously has a big performance penalty. > > sync=disabled >Synchronous requests are disabled. File system transactions >only commit to stable storage on the next DMU transaction group >commit which can be many seconds. This option gives the >highest performance, with no risk of corrupting the pool. >However, it is very dangerous as ZFS is ignoring the synchronous > transaction >demands of applications such as databases or NFS. >Setting sync=disabled on the currently active root or /var >file system may result in out-of-spec behavior or application data >loss and increased vulnerability to replay attacks. >Administrators should only use this when these risks are understood. > > The property can be set when the dataset is created, or dynamically, > and will take effect immediately. To change the property, an > administrator can use the standard 'zfs' command. For example: > > # zfs create -o sync=disabled whirlpool/milek > # zfs set sync=always whirlpool/perrin I read that this property is not inherited and I can't see why. If what I read is up-to-date, could you tell why? -- Pawel Jakub Dawidek http://www.wheelsystems.com p...@freebsd.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! pgpnwVhYvicjy.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
