From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Balzer Subject: RAID5 TRIM/DISCARD user land support (fstriim and mkfs) Date: Mon, 10 Aug 2015 16:46:57 +0900 Message-ID: <20150810164657.75bae079@batzmaru.gol.ad.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hello, Debian system, tested both Wheezy and Jessie, thus 3.16 kernel with backports. 8 SSD RAID5, of course with raid456.devices_handle_discard_safely set to 1. I can re-mount it with discard w/o a problem: --- EXT4-fs (md4): re-mounted. Opts: stripe=112,data=ordered,discard --- However fstrim whines about "FITRIM ioctl failed: Operation not supported" and mkfs.ext4 unsurprisingly doesn't discard things when invoked. The same HW/OS combo works fine with RAID10. When looking at the sysfs entries for that MD device the fact that /sys/class/block/md4/queue/discard_zeroes_data is 0 doesn't instill me with hope or confidence Now while the SSDs in question (Intel DC S3610s) don't really need TRIM really would have liked them to be able to start with a clean slate so to speak. Any insights? Christian -- Christian Balzer Network/Systems Engineer chibi@gol.com Global OnLine Japan/Fusion Communications http://www.gol.com/