Date: Mon, 2 Dec 2013 18:46:42 +0100 From: Polytropon <freebsd@edvax.de> To: "Mike." <the.lists@mgm51.com> Cc: freebsd-questions@freebsd.org Subject: Re: gmirror, gpart and MBR vs GPT in the Handbook Message-ID: <20131202184642.d35c4548.freebsd@edvax.de> In-Reply-To: <201312021235030914.007AF1DF@smtp.24cl.home> References: <201311301303210813.05DE187E@smtp.24cl.home> <alpine.BSF.2.00.1311301352140.99113@wonkity.com> <201312011121580096.005D00FB@smtp.24cl.home> <alpine.BSF.2.00.1312011016490.5791@wonkity.com> <201312021213320528.00673D5F@smtp.24cl.home> <20131202182623.43331984.freebsd@edvax.de> <201312021235030914.007AF1DF@smtp.24cl.home>
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On Mon, 02 Dec 2013 12:35:03 -0500, Mike. wrote: > On 12/2/2013 at 6:26 PM Polytropon wrote: > > |On Mon, 02 Dec 2013 12:13:32 -0500, Mike. wrote: > |> My understanding is that MBR can be used with drives only up > to > |> and including 2TB in size. So if I use MBR, the maximum > drive > |> size I could use would be 2TB. Is that correct? > |[...] > |Regarding UFS's 2 TB limitation: > | > |http://www.freebsd.org/projects/bigdisk/ > | > |Additionally, MBR can be troublesome on bigger hard disks > |or stripes. > | > |http://www.freebsd.org/doc/handbook/bsdinstall-partitioning.html > > | > |Today's consensus seems to be: > | > |If you use ZFS, let ZFS deal with everything. > | > |If you use UFS, use gpart for preparation work. Use GPT when > |possible, MBR only in exceptions, and dedicated if and only > |if you really _really_ know what you're doing. :-) > ============= > > > Following the bsdinstall-partitioning link you cited, and then > following a link on that page, I wind up here: > > http://en.wikipedia.org/wiki/Master_boot_record > > which states: > > "...The organization of the partition table in the MBR limits > the maximum addressable storage space of a disk to 2 TB ...." > > > That (and other places) is where I got the 2TB limit of MBR into > my head. Am I misunderstanding that statement? I think you're correct regarding this finding: The data type 2^32 (because of 32 bit) defines the 2 TB limit. It applies both on MBR (which stores 32 bit values) and UFS (which also stores 32 bit values). However, I've never dealt with disks > 2 TB _and_ UFS before, so I can't add specific individual findings. :-) Again, consensus seems to be: If you have big disks, use ZFS. You use ZFS because the big disks are built into or attached to big computers with sufficient RAM, so it won't be a problem. -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...
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