Date: Fri, 30 Aug 2013 14:09:57 +0200 From: Maurizio Vairani <maurizio.vairani@cloverinformatica.it> To: Ronald Klop <ronald-freebsd8@klop.yi.org>, Johan Hendriks <joh.hendriks@gmail.com> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: Boot problem if a ZFS log device is missing Message-ID: <52208B95.2010100@cloverinformatica.it> In-Reply-To: <op.w2mn9nuu8527sy@212-182-167-131.ip.telfort.nl> References: <521F05F0.4090607@cloverinformatica.it> <521F0DEB.20408@FreeBSD.org> <52205507.4030802@cloverinformatica.it> <52207AD5.2070608@gmail.com> <op.w2mn9nuu8527sy@212-182-167-131.ip.telfort.nl>
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On 30/08/2013 13.45, Ronald Klop wrote: > On Fri, 30 Aug 2013 12:58:29 +0200, Johan Hendriks > <joh.hendriks@gmail.com> wrote: > >> Maurizio Vairani wrote: >>> On 29/08/2013 11.01, Andriy Gapon wrote: >>>> on 29/08/2013 11:27 Maurizio Vairani said the following: >>>>> I am able to boot the PC without a cache device but not without a >>>>> log device. Why ? >>>> The log could potentially contain uncommitted entries. Without the >>>> log device >>>> there is no knowing if it did or did not. And if it did then the >>>> pool is >>>> inconsistent state without the log device and so it can not be >>>> imported. >>>> >>>> The cache is not persistent and so there is nothing needed from it >>>> upon a boot. >>>> >>> Thank you for the clear and concise reply. >>> >>> Yesterday I have done some test. If I remove the stick from the USB >>> port, before the shutdown the PC, it don't crash but continues to >>> works. Then I am able to reboot the laptop without inserting the >>> stick with a pool that works in degraded mode. >>> >>> From the end user point of view a PC should always boot, even with a >>> missing ZFS log device. >>> >>> Regards >>> Maurizio >>> >>> _______________________________________________ >>> freebsd-fs@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs >>> To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >> I do not agree with the following. >> From the end user point of view a PC should always boot, even >> with a missing ZFS log device. >> >> I think it should give you a option to import the pool or not import >> the pool! No problem I agree, a step in the right direction. >> There could be a situation when you are not sure that the ZIL is >> commited, in that situation it would be handy if you can suspend the >> boot and make sure the ZIL is there when you reboot or import after >> you attached the ZIL. >> I would hate it when it corrups my data just because we always >> import. with or without the ZIL. >> >> In your test you remove the ZIL, and when you reboot then it imports >> correctly, as far as my knowledge goes this is ok, because when the >> pool is exported there is no left data in the ZIL, it was not there >> when we exported, so we can import even without the missing ZIL >> without problem. > > I think he was just lucky his system wasn't writing a lot to the ZIL > at the moment of removal. So his system was in a consistent state. > Otherwise you just miss data which is in the ZIL and not on disk. I have removed the stick when there isn't R/W to the disk. > BTW: Not everything goes through the ZIL. It is not the same as a > journal. Only sync writes go to the ZIL. If you don't use databases or > NFS or other software which wants to make sure data is on stable > storage, you might rarely use the ZIL. Thanks for the explanation. > > Ronald. > >> >> regards >> Johan >> >> >> >> >> >> _______________________________________________ >> freebsd-stable@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-stable >> To unsubscribe, send any mail to >> "freebsd-stable-unsubscribe@freebsd.org" Regards Maurizio
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