Re: [ZODB-Dev] Re: Anybody using ZODB with no calls to fsync in production?
On Oct 12, 2006, at 5:01 PM, Tres Seaver wrote: +1. Sessions might be a good example of a storage using 'fsync-behavior=None': you would get the speedup, and the ability to survive a restart, without needing to treat the data as "precious". This is an interesting point, and it makes me wonder if there would be interest having the fsync behavior vary on a per-transaction basis instead of a per-storage basis. Maybe the client submitting transactions that are just Session-like changes could include a message to the server indicating that this transaction is not precious. ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
[ZODB-Dev] Re: Anybody using ZODB with no calls to fsync in production?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Chris Withers wrote: > +1 from me too, this feels like a really good proposal :-) +1. Sessions might be a good example of a storage using 'fsync-behavior=None': you would get the speedup, and the ability to survive a restart, without needing to treat the data as "precious". > Jim Fulton wrote: >> +1 >> >> Lennart Regebro wrote: >>> On 10/11/06, Roché Compaan <[EMAIL PROTECTED]> wrote: http://mail.zope.org/pipermail/zodb-dev/2004-July/007682.html >>> >>> I read this thread, and it seems to me that the ultimate solution >>> would be to have a setting for FSStorage, say "fsync-behaviour" with >>> the options of "single", "double", "none" or "interval". We'd need an >>> explaining text too. Something like: >>> >>> fsync-behaviour: Determines when fsync is called. Default: single. >>> >>> Options: >>> >>> Single: Calls fsync once per transaction. Gives you reasonable data >>> reliability in most cases. You should in a crash only lose one >>> transaction. >>> >>> Double: Calls fsync before marking transaction as complete as well as >>> after marking it as complete. This setting is only useful if you have >>> configured the complete storage chain (operating system, filesystem, >>> drivers, controllers and disks) will not let fsync return until data >>> is safely and completely written to disk. In most cases and without >>> configuration of the complete storage chain, this setting will slow >>> down FSStorage without actually increasing the reliability of data >>> written to disk. >>> >>> Interval: Will call fsync only every couple of transactions, with the >>> interval determined by the setting "fsync-interval". This is good for >>> write-intensive applications where you don't mind loosing a couple of >>> transactions if the computer should crash. >>> >>> None: Will never call fsync. Good for applications of high write load >>> where the data is not critical. Never ever use this setting on >>> windows, as it on windows makes it highly likely that data will not be >>> written to disk at all, and a crash could quite likely make you loose >>> all your changes. >>> >> >> > - -- === Tres Seaver +1 202-558-7113 [EMAIL PROTECTED] Palladion Software "Excellence by Design"http://palladion.com -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.2.2 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFLq00+gerLs4ltQ4RAgIPAJ9sX4MoQ/slgP2C8UvONdpobBuuewCghisA cylxDrhhyNFd1WDOjgtRsi4= =JmrL -END PGP SIGNATURE- ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
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Re: [ZODB-Dev] Anybody using ZODB with no calls to fsync in production?
+1 from me too, this feels like a really good proposal :-) Chris Jim Fulton wrote: +1 Lennart Regebro wrote: On 10/11/06, Roché Compaan <[EMAIL PROTECTED]> wrote: http://mail.zope.org/pipermail/zodb-dev/2004-July/007682.html I read this thread, and it seems to me that the ultimate solution would be to have a setting for FSStorage, say "fsync-behaviour" with the options of "single", "double", "none" or "interval". We'd need an explaining text too. Something like: fsync-behaviour: Determines when fsync is called. Default: single. Options: Single: Calls fsync once per transaction. Gives you reasonable data reliability in most cases. You should in a crash only lose one transaction. Double: Calls fsync before marking transaction as complete as well as after marking it as complete. This setting is only useful if you have configured the complete storage chain (operating system, filesystem, drivers, controllers and disks) will not let fsync return until data is safely and completely written to disk. In most cases and without configuration of the complete storage chain, this setting will slow down FSStorage without actually increasing the reliability of data written to disk. Interval: Will call fsync only every couple of transactions, with the interval determined by the setting "fsync-interval". This is good for write-intensive applications where you don't mind loosing a couple of transactions if the computer should crash. None: Will never call fsync. Good for applications of high write load where the data is not critical. Never ever use this setting on windows, as it on windows makes it highly likely that data will not be written to disk at all, and a crash could quite likely make you loose all your changes. -- Simplistix - Content Management, Zope & Python Consulting - http://www.simplistix.co.uk ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] Anybody using ZODB with no calls to fsync in production?
+1 Lennart Regebro wrote: On 10/11/06, Roché Compaan <[EMAIL PROTECTED]> wrote: http://mail.zope.org/pipermail/zodb-dev/2004-July/007682.html I read this thread, and it seems to me that the ultimate solution would be to have a setting for FSStorage, say "fsync-behaviour" with the options of "single", "double", "none" or "interval". We'd need an explaining text too. Something like: fsync-behaviour: Determines when fsync is called. Default: single. Options: Single: Calls fsync once per transaction. Gives you reasonable data reliability in most cases. You should in a crash only lose one transaction. Double: Calls fsync before marking transaction as complete as well as after marking it as complete. This setting is only useful if you have configured the complete storage chain (operating system, filesystem, drivers, controllers and disks) will not let fsync return until data is safely and completely written to disk. In most cases and without configuration of the complete storage chain, this setting will slow down FSStorage without actually increasing the reliability of data written to disk. Interval: Will call fsync only every couple of transactions, with the interval determined by the setting "fsync-interval". This is good for write-intensive applications where you don't mind loosing a couple of transactions if the computer should crash. None: Will never call fsync. Good for applications of high write load where the data is not critical. Never ever use this setting on windows, as it on windows makes it highly likely that data will not be written to disk at all, and a crash could quite likely make you loose all your changes. -- Jim Fulton mailto:[EMAIL PROTECTED] Python Powered! CTO (540) 361-1714http://www.python.org Zope Corporation http://www.zope.com http://www.zope.org ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] Anybody using ZODB with no calls to fsync in production?
On 10/11/06, Roché Compaan <[EMAIL PROTECTED]> wrote: http://mail.zope.org/pipermail/zodb-dev/2004-July/007682.html I read this thread, and it seems to me that the ultimate solution would be to have a setting for FSStorage, say "fsync-behaviour" with the options of "single", "double", "none" or "interval". We'd need an explaining text too. Something like: fsync-behaviour: Determines when fsync is called. Default: single. Options: Single: Calls fsync once per transaction. Gives you reasonable data reliability in most cases. You should in a crash only lose one transaction. Double: Calls fsync before marking transaction as complete as well as after marking it as complete. This setting is only useful if you have configured the complete storage chain (operating system, filesystem, drivers, controllers and disks) will not let fsync return until data is safely and completely written to disk. In most cases and without configuration of the complete storage chain, this setting will slow down FSStorage without actually increasing the reliability of data written to disk. Interval: Will call fsync only every couple of transactions, with the interval determined by the setting "fsync-interval". This is good for write-intensive applications where you don't mind loosing a couple of transactions if the computer should crash. None: Will never call fsync. Good for applications of high write load where the data is not critical. Never ever use this setting on windows, as it on windows makes it highly likely that data will not be written to disk at all, and a crash could quite likely make you loose all your changes. -- Lennart Regebro, Nuxeo http://www.nuxeo.com/ CPS Content Management http://www.nuxeo.org/ ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] Anybody using ZODB with no calls to fsync in production?
You can read what is said about it on PostgreSQL, which has a similar setting. The setting could be very good for (for example) restoring from a backup, where performance is most important and, in case of crash, you have a backup anyway. Regards Marco On 10/11/06, Roché Compaan <[EMAIL PROTECTED]> wrote: Has anybody been using Zope with a ZODB patched to not call fsync since the fsync thread in July 2004: http://mail.zope.org/pipermail/zodb-dev/2004-July/007682.html I just took Tim Peters' timefsync.py for a spin on some of our servers and got transaction rates from 4 to 10 times faster, compared to running ZODB with a call to fsync. I'm tempted to deploy ZODB without fsync on some production FileStorage instances. Will I regret it? -- Roché Compaan Upfront Systems http://www.upfrontsystems.co.za ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev -- Marco Bizzarri http://notenotturne.blogspot.com/ ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] Anybody using ZODB with no calls to fsync in production?
On 10/11/06, Roché Compaan <[EMAIL PROTECTED]> wrote: I'm tempted to deploy ZODB without fsync on some production FileStorage instances. Will I regret it? There was a mention that most SQL-databases do it only each X commits. That might be an idea? That means that in worst case you lose X transactions if the computer crashes, I think. -- Lennart Regebro, Nuxeo http://www.nuxeo.com/ CPS Content Management http://www.nuxeo.org/ ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] Anybody using ZODB with no calls to fsync in production?
Roché Compaan wrote: I'm tempted to deploy ZODB without fsync on some production FileStorage instances. Will I regret it? Well, let us know when you find out ;-) Chris -- Simplistix - Content Management, Zope & Python Consulting - http://www.simplistix.co.uk ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev