Date: Fri, 07 Feb 2014 16:50:37 -0600 From: Mark Felder <feld@FreeBSD.org> To: Warren Block <wblock@wonkity.com> Cc: freebsd-fs@freebsd.org Subject: Re: Using the *real* sector/block size of a mass storage device for ZFS Message-ID: <1391813437.29897.80736933.1F6388D0@webmail.messagingengine.com> In-Reply-To: <alpine.BSF.2.00.1402071513370.20481@wonkity.com> References: <1487AF77-7731-4AF8-8E44-FF814BB8A717@ebureau.com> <1391808195.4799.80708189.5CAD8A4E@webmail.messagingengine.com> <alpine.BSF.2.00.1402071513370.20481@wonkity.com>
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On Fri, Feb 7, 2014, at 16:19, Warren Block wrote: > On Fri, 7 Feb 2014, Mark Felder wrote: > > > On Fri, Feb 7, 2014, at 14:44, Dustin Wenz wrote: > >> We have been upgrading systems from FreeBSD 9.2 to 10.0-RELEASE, and I'm > >> noticing that all of my zpools now show this status: "One or more devices > >> are configured to use a non-native block size. Expect reduced > >> performance." Specifically, each disk reports: "block size: 512B > >> configured, 4096B native". > >> > >> I've checked these disks with diskinfo and smartctl, and they report a > >> sector size of 512B. I understand that modern disks often use larger > >> sectors due to addressing limits, but I'm unsure how ZFS can disagree > >> with these other tools. > >> > >> In any case, it looks like I will need to rebuild every zpool. There are > >> many thousands of disks involved and the process will take months (if not > >> years). How can I be I sure that this is done correctly this time? Will > >> ZFS automatically choose the correct block size, assuming that it's > >> really capable of this? > >> > >> In the meantime, how can I turn off that warning message on all of my > >> disks? "zpool status -x" is almost worthless due to the extreme number of > >> errors reported. > >> > > > > ZFS is doing the right thing by telling you that you should expect > > degraded performance. The best way to fix this is to use the gnop method > > when you build your zpools: > > > > gnop create -S 4096 /dev/da0 > > gnop create -S 4096 /dev/da1 > > zpool create data mirror /dev/da0.nop /dev/da1.nop > > > > Next reboot or import of the zpool will use the regular device names > > with the correct ashift for 4K drives. > > But remember that this does not fix alignment, and if the partitions are > not aligned with 4K blocks, at least write performance will suffer. > I often use raw devices ever since ZFS has had the ability to tolerate slight differences in disk sizes.
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