Date: Mon, 8 Feb 2010 15:10:37 -0500 From: "b. f." <bf1783@googlemail.com> To: Jerry McAllister <jerrymc@msu.edu> Cc: freebsd-questions@freebsd.org Subject: Re: Should root partition be first partition? Message-ID: <d873d5be1002081210oca8c748jd01da80b4faef1fb@mail.gmail.com> In-Reply-To: <20100208200444.GA58228@gizmo.acns.msu.edu> References: <d873d5be1002081137p7c547a28u21203b9e6191e3d1@mail.gmail.com> <20100208200444.GA58228@gizmo.acns.msu.edu>
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On 2/8/10, Jerry McAllister <jerrymc@msu.edu> wrote: > On Mon, Feb 08, 2010 at 02:37:30PM -0500, b. f. wrote: > >> > You can even >> >leave gaps between partitions if you want, but that is pretty crazy >> >since it just wastes some of the available space. >> > >> >There have been quite a lot of recommendations on how to lay out a disk >> >for best performance, based on the observation that disk access times >> >vary depending on how far away the data is from the spindle, and the >> >expected usage patterns for the partition. Like any such advice, it >> >has tended to become less valid over time. Modern disks really don't >> >have any physical meaning to the Cylinder/Head/Sector style addressing >> >schemes[*] nowadays -- and you're pretty much bound to be using LBA >> >style addressing anyhow. Also, machines nowadays have so much RAM that >> >(a) swap is hardly ever used and (b) access to popular files is >> >frequently answered out of VM caches rathe than needing disk IO. >> >> >> Layout is still important, and leaving some blank space may not be so >> crazy. Here I'm thinking not so much of ordering (although one would >> probably be best served by the recommended default ordering), but of >> alignment, size, raid/stripe/concat configuration, and file system >> block and fragment size selection. Witness the (as much as tenfold) >> performance difference from simple changes, highlighted in the recent >> thread entitled 'File system blocks alignment' on freebsd-arch@ during >> December 2009 - January 2010, beginning with: >> >> http://lists.freebsd.org/pipermail/freebsd-arch/2009-December/009770.html >> >> If you're laying out a new disk, you may as well take a few minutes >> and get the most out of it, even if you're not going to invest in a >> lot of new hardware. > > The system nowdays does all that figuring for you and manages > boundaries reasonably. > > ////jerry > That does not seem to be the conclusion of those who contributed to the thread I cited, although "reasonably" is open to interpretation.
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