Hi, I'm preparing to set up a new 1TB SSD (Samsung 850pro) for use in an OpenBSD laptop. Like every other SSD I've seen, this SSD uses a 4K byte block size.
I'm planning to use softraid crypto for this disk, and mount all the main filesystems with softdep and noatime. I understand that fdisk and disklabel partition boundaries should be multiples of 4K bytes (= 8 512-byte sectors), e.g., starting the 'a' disklabel partition at offset=64 512-byte sectors is much better than starting it at offset=63. I've read the misc@ thread on "4k sector disks" from 2010, http://marc.info/?l=openbsd-misc&m=127071305915101&w=1 http://marc.info/?l=openbsd-misc&m=127149466227162&w=1 tedu's 2011 blog post "lessons learned about TRIM", http://www.tedunangst.com/flak/post/lessons-learned-about-TRIM and the 2014 daemonforums thread on SSD installs, http://daemonforums.org/showthread.php?t=8630 Questions: * Should I set the FFS fragment size (newfs -f) to 4096 or larger? * What about the FFS sector size (newfs -S): should this be left at its default, or set to 4096? * Are there other fdisk and/or newfs parameters which should be set differently than I'd set them for a mechanical hard disk of similar size? * What are the tradeoffs between FFS (newfs -O 1) and FFS2 (newfs -O 2)? Since this is OpenBSD, perhaps I should rephrase this question as "what Fine Manual should I have read to learn about these tradeoffs?" * Does or should using softraid crypto change the answers to any of the above questions? Thanks, -- -- "Jonathan Thornburg [remove -color to reply]" <jthorn4...@gmail-pink.com> Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA "There was of course no way of knowing whether you were being watched at any given moment. How often, or on what system, the Thought Police plugged in on any individual wire was guesswork. It was even conceivable that they watched everybody all the time." -- George Orwell, "1984"
