Date: Thu, 1 Aug 2013 00:22:38 -0400 From: J David <j.david.lists@gmail.com> To: Shane Ambler <FreeBSD@shaneware.biz> Cc: freebsd-stable@freebsd.org Subject: Re: Problem with zfsloader on 9.2-BETA2 Message-ID: <CABXB=RTt5t9EAbw0Vi-H9_kYnzkcry1wqwv6TtW6Ntmz5UqCBA@mail.gmail.com> In-Reply-To: <51F9D7C3.7020806@ShaneWare.Biz> References: <CABXB=RRhVDdKCidwnrji1qR41Rx7uvs2Lx1ZPF1FREOHcnm5bg@mail.gmail.com> <alpine.BSF.2.00.1307311107240.1327@mail.fig.ol.no> <CABXB=RR7E2s5GU29ZgU1hBk4MqkvrO95-RBg4TE6ahozP6KmCg@mail.gmail.com> <51F9D7C3.7020806@ShaneWare.Biz>
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On Wed, Jul 31, 2013 at 11:36 PM, Shane Ambler <FreeBSD@shaneware.biz> wrote: > I think that 8M partition looks weird. It looks like a leftover from a > previous config? We leave some space at the end of drives in case we need to change drive vendors. Sometimes vendor A's drives are a few sectors smaller than vendor B's for the same advertised capacity. Accordingly, 6a945a3b-1dd2-11b2-99a6-080020736631 is a "reserved" GPT partition type GUID. It is a GPT way of saying, "This space intentionally left blank." It also hypothetically leaves some space at the end of the disk for GEOM functionality not foreseen at setup time, though in practice with ZFS that doesn't come up. > Two things I would think to consider - the odd alignment of the > partition. Most recent drives benefit from 4K alignment. These disks are not 4k disks. Even if they were, or if we swap out to 4k drives in the future, the ZFS data partitions absolutely are 4K aligned; they start at sector 256, which is 128k (32 4k sectors) into the disk. But even if they weren't that wouldn't prevent the system from booting. Nor would empty space at the end of the drive. Or at least shouldn't. And in fact didn't, until the upgrade from 8.4 to 9.2. Which is the issue at hand. Thanks!
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