Date: Wed, 10 Jun 2020 07:22:01 +0000 From: bugzilla-noreply@freebsd.org To: doc@FreeBSD.org Subject: [Bug 247136] Handbook, section 2.3.1.1: dd(1) command uses "bs=1M" (slow), should be "bs=4k" (/much/ faster) Message-ID: <bug-247136-9@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=247136 Bug ID: 247136 Summary: Handbook, section 2.3.1.1: dd(1) command uses "bs=1M" (slow), should be "bs=4k" (/much/ faster) Product: Documentation Version: Latest Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: Documentation Assignee: doc@FreeBSD.org Reporter: t.eichstaedt@gmx.net Dear documenters, 1. unless there's any technical reason to use a blocksize of 1M, this should be changed. Unfortunately I do not have the insight to judge that, so please check w/ s/o who knows more about this. All images I wrote w/ "bs=1k" so far worked, so I'd assume that either all those images were integer multiples of 1M, or there's no technical reason to pad the end w/ zeroes to the next 1M boundary. Rationale: (AFAIK) The native blocksize of USB media is 4k. Writing an image w/ the native blocksize is about 7 times faster (at least on USB 2). 2. I'd like to suggest to add "status=progress" to the dd(1) arguments, because this command can take a few minutes (on USB 1/2) and it's much nicer to have some reply about what's going on. Somehow like this: "older versions of dd(1) do not support 'status=progress'. If it fails, simply use the command w/o it." I just stumbled over this when I was preparing the media for an installation, and instead of just doing what I used to do ("dd bs=1k conv=sync"), I checked the handbook to see if s/th changed. Nothing changed, but using "bs=1M" was significantly slower than "bs=1k". So I thought: both is wrong, should be 4k! And yes - using "bs=4k" is in fact much faster. The same bad example occurs in the man page of dd(1) (last example) With kind regards, Torsten -- You are receiving this mail because: You are the assignee for the bug.help
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