Date: Tue, 17 Nov 2015 09:22:56 +0100 From: Miroslav Lachman <000.fbsd@quip.cz> To: "Patrick M. Hausen" <hausen@punkt.de>, Freddie Cash <fjwcash@gmail.com> Cc: freebsd-scsi@freebsd.org, freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: ZFS on labelled partitions Message-ID: <564AE3E0.9060209@quip.cz> In-Reply-To: <878D84A9-4553-413B-ACA4-5ABF499F28C1@punkt.de> References: <5644FF09.9090200@free.de> <CA%2BE3k93QrUFA3BvhoswkVDXh2bR2aLYG6Z0TOrisVvNL=%2BMZVA@mail.gmail.com> <56472686.5030301@free.de> <20151114143104.GA41119@in-addr.com> <7710CBCC-E68F-4454-9E29-E50ED1C6B511@sarenet.es> <CAN6yY1sH0PnnF_AGwDsA75i_Z6ptOr4J0c_Gqrt%2BRFO6eZsW-Q@mail.gmail.com> <CAOjFWZ4Js65gQZc6rbT9SKg-jZozziTa=JGpJys6HyejdgWP%2Bg@mail.gmail.com> <20151116205734.GM48728@zxy.spb.ru> <CAOjFWZ49A8b6g=mQL3jzJaNX-Lf%2BuDCvmscyB6F4tr7Ax=HMbg@mail.gmail.com> <878D84A9-4553-413B-ACA4-5ABF499F28C1@punkt.de>
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Patrick M. Hausen wrote on 11/17/2015 09:08: > Hi, all, > >> Am 16.11.2015 um 22:19 schrieb Freddie Cash <fjwcash@gmail.com>: >> >> You label the disks as they are added to the system the first time. That >> way, you always know where each disk is located, and you only deal with the >> labels. > > we do the same for obvious reasons. But I always wonder about the possible > downsides, because ZFS documentation explicitly states: > > ZFS operates on raw devices, so it is possible to create a storage pool comprised of logical > volumes, either software or hardware. This configuration is not recommended, as ZFS works > best when it uses raw physical devices. Using logical volumes might sacrifice performance, > reliability, or both, and should be avoided. > > (from http://docs.oracle.com/cd/E19253-01/819-5461/gbcik/index.html) > > Can anyone shed some lght on why not using raw devices might sacrifice > performance or reliability? Or is this just outdated folklore? It was on Solaris but not on FreeBSD. If you were using partitions on Solaris the drive cache was disabled (or something like that, I am not 100% sure) Miroslav Lachman
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