Date: Fri, 09 Sep 2016 08:47:00 -0500 From: Brandon J. Wandersee <brandon.wandersee@gmail.com> To: "Brandon J. Wandersee" <brandon.wandersee@gmail.com> Cc: Perry Hutchison <perryh@pluto.rain.com>, wblock@wonkity.com, freebsd-questions@freebsd.org Subject: Re: "gpart add" falsely claiming "No space left on device" Message-ID: <86poodqj6z.fsf@WorkBox.Home> In-Reply-To: <86r38tqjpw.fsf@WorkBox.Home> References: <57ce6e64.EITkODjuwy6pZ4L%2B%perryh@pluto.rain.com> <alpine.BSF.2.20.1609060814030.1903@wonkity.com> <57cf9b95.Zj/JGHeshaKL6Zr5%perryh@pluto.rain.com> <alpine.BSF.2.20.1609070643120.24506@wonkity.com> <57d0f29b.3QNvCze7LJDzs0SU%perryh@pluto.rain.com> <86wpimm6om.fsf@WorkBox.Home> <57d276f6.CwaoGNki0kQYiZns%perryh@pluto.rain.com> <86r38tqjpw.fsf@WorkBox.Home>
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Brandon J. Wandersee writes: >> "Brandon J. Wandersee" <brandon.wandersee@gmail.com> wrote: >> >>> '-s' defaults to everything available. >> >> "available" on the entire disk (as if no partitions were defined), >> the first free block, or the largest free block? (One hopes, not >> the sum of all free blocks :) Again, the man page should say! > > "Available" as in "available based on logical context." If no > partitions are present on the disk, you get one partition starting at > the first sector and ending at the last, less any space needed for > scheme-specific metadata and buffer space resulting from '-a' or '-b.' > If partitions exist, you'll get a partition starting at the first free > sector and extending until you hit another partition or the end of the > disk, assuming the partition can be created in that space while > abiding by traits set with '-a' or '-b'. > > Obviously partitions can only consist of contiguous space, and the > command will not automatically destroy an existing partition > layout. `gpart add` *adds a partition.* Deleting and resizing > partitions, and destroying tables, are handled by separate commands. > >> [The need to specify partition type] _could_ be implied by its not >> being bracketed in the usage section, if not for the fact that -b and >> -s (which apparently do have defaults, even though the man page does >> not say what they are) are not bracketed either. > >> There's no [ATTRIBUTES] section in the gpart(8) man page I'm looking at (on >> FreeBSD 8.1) ... There's no BOOTSTRAPPING section in this gpart(8) >> man page, either. > > All of this---including the bracketed '-s' and '-b'---are present in > the latest version of the man page.[1] 8.1 hasn't been supported for four > years, so it's documentation won't be updated. I should add that you *can* install the up-to-date documentation manually, either from source (explained in the "Handbook") or with the misc/freebsd-doc-* port/package. Replace '*' with your native language. But since it looks like you're working on upgrading to 10.3, just use the online docs. >> Alignment to 4k makes sense if the physical sector size is 4k (as >> is often the case with newer disk drives) -- but 1M? Seems a bit >> much, which is why it would be useful for that page to include a >> more detailed explanation. > > Aligning to 1Mb guarantees that a partition is aligned to physical > sector boundaries regardless a disk's actual or reported sector > size. Newer HDD firmwares often report having 512k sectors for > backwards compatibility, even when they have 4k sectors, while SSDs > don't really have an industry-standard sector size and report whatever > the manufacturer feels like. But in all cases, they're factors of > 1Mb. The point is that you either spend some time and effort > researching each disk model in the system and doing some math, or you > just sacrifice a megabyte or two for guaranteed alignment and be done > with it. > > [1]: https://www.freebsd.org/cgi/man.cgi?query=gpart&apropos=0&sektion=8&manpath=FreeBSD+10.3-RELEASE+and+Ports&arch=default&format=html -- :: Brandon J. Wandersee :: brandon.wandersee@gmail.com :: -------------------------------------------------- :: 'The best design is as little design as possible.' :: --- Dieter Rams ----------------------------------
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