Date: Thu, 22 Nov 2012 22:56:50 -0700 (MST) From: Warren Block <wblock@wonkity.com> To: Shane Ambler <FreeBSD@shaneware.biz> Cc: freebsd questions list <freebsd-questions@freebsd.org> Subject: Re: FreeBSD on SSD on ASUS P5KPL-C Message-ID: <alpine.BSF.2.00.1211222232330.20251@wonkity.com> In-Reply-To: <50AEDD3E.8030007@ShaneWare.Biz> References: <CAAHVa8thx4_fjQrTUwwGxERtCvTX9NnR59JxH7gQ38tq7irCZw@mail.gmail.com> <CAHHBGkph5j86wDpobasdtM%2BJZMQKt2eqcn8LKd4V0NzyDxR3Tw@mail.gmail.com> <CAAHVa8vm6vFa8ajiOJT3VWnvcZasdQM%2BnaJdjG9eLx%2Bj5F80CA@mail.gmail.com> <50A83993.50401@ShaneWare.Biz> <CAAHVa8uf65aaEWcKehojc0M67Psrn8Mpfj9GT=XR4GK47c%2BBWA@mail.gmail.com> <alpine.BSF.2.00.1211191235400.28618@wonkity.com> <CAAHVa8tZBPGPyuuU0bSwyPdN5ZtW_d4t9cJN7CcxEEaUXO7OGw@mail.gmail.com> <alpine.BSF.2.00.1211191801060.31205@wonkity.com> <CAAHVa8vsXUPn%2BndPsbR3GCdneu5iQSfVt0v--GgDvRvZL8bSCA@mail.gmail.com> <alpine.BSF.2.00.1211212020420.10378@wonkity.com> <alpine.BSF.2.00.1211212118100.10378@wonkity.com> <50AEDD3E.8030007@ShaneWare.Biz>
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On Fri, 23 Nov 2012, Shane Ambler wrote: > On 22/11/2012 14:49, Warren Block wrote: >> On Wed, 21 Nov 2012, Warren Block wrote: >> >>> Got a chance to set up a scratch drive and check this. Turns out >>> I left out the step of creating a "slice" (MBR partition) to hold >>> the FreeBSD partitions. Also, GPT labels cannot be used in an >>> MBR. Fixed below. I will probably add this to my disk setup >>> article because it has come up more than once. >> >> The fdisk/bsdlabel section of my disk setup article has been >> rewritten to use gpart. Feedback welcome. >> >> http://www.wonkity.com/~wblock/docs/html/disksetup.html > > Something I meant to ask before - is there any benefit to following the > steps described in > http://www.aisecure.net/2012/01/16/rootzfs/ My guide is based on using UFS. ZFS or other filesystems will also benefit from block alignment, but the methods to get there can be different. > The step of using gnop is meant to trick zfs into believing the disk has > 4K sector size to improve performance, which I would think zfs would be > able to figure out by talking to the disk. Unless ZFS is put on a bare, unpartitioned disk, configuration for performance is better left to the user. It's a pain to correct automatic configs when they guess wrong. > Does partitioning hide the sector size or would the step of aligning > the partition start to a 4k sector unhide the 4k size? > Or are these steps just a waste of time? It's not about hiding the device's native block size, it's about getting the filesystem to do aligned I/O so the device can just read or write a single 4K block instead of part of one and part of another.
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