On 01.03.2019 04:41, Stuart D. Gathman wrote: > On Fri, 1 Mar 2019, Cesare Leonardi wrote: > >> I've done the test suggested by Stuart and it seems to contradict this. >> I have pvmoved data from a 512/512 (logical/physical) disk to a newly added 512/4096 disk but I had no data corruption. Unfortunately I haven't any native 4k disk to repeat the same test. > > Use a loopback device with logical block size set to 4096 to confirm > that your test does detect corruption (using the same LV, filesystem, > data). > > I believe by "physical sector", the original reporter means logical, > as he was using an encrypted block device that was virtual - there > was no "physical" sector size. It was "physical" as far as the > file system was concerned - where "physical" means "the next layer > down". Well, let me cite from https://www.saout.de/pipermail/dm-crypt/2019-February/006078.html from Ondrej Kozina which is also referenced in my original post: "dm-crypt advertise itself as a block device with physical sector size *at least* equal to encryption sector size. Traditionally it's been only 512B. So classical dm-crypt mapped over device with phys. sector size = 512B has no impact. If you mapped dm-crypt over block device with native physical sector size = 4096 you got dm-crypt exposing same limits as underlying block device. Again no problem. Just internally dm-crypt performed encryption on 512B blocks, but it had no impact on exposed limits. But things get a bit different with encryption sector size > 512B. If you map dm-crypt with encryption sector size set to 4096B over block device with physical sector size = 512B, dm-crypt must increase device limits to 4096. Because when it does encryption it must be aligned to 4096 bytes (and same wrt minimal i/o size)." > > Indeed, even the rotating disk drives make the physical sector size > invisible except to performance tests. SSD drives have a "sector" size > of 128k or 256k - the erase block, and performance improves when aligned > to that. > -- Ingo Franzki eMail: ifranzki@xxxxxxxxxxxxx Tel: ++49 (0)7031-16-4648 Fax: ++49 (0)7031-16-3456 Linux on IBM Z Development, Schoenaicher Str. 220, 71032 Boeblingen, Germany IBM Deutschland Research & Development GmbH / Vorsitzender des Aufsichtsrats: Matthias Hartmann Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294 IBM DATA Privacy Statement: https://www.ibm.com/privacy/us/en/ _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
