From mboxrd@z Thu Jan 1 00:00:00 1970 From: Holger Kiehl Subject: Re: RAID5 TRIM/DISCARD user land support (fstriim and mkfs) Date: Mon, 10 Aug 2015 08:59:24 +0000 (UTC) Message-ID: References: <20150810164657.75bae079@batzmaru.gol.ad.jp> <20150810175336.5582e9fd@batzmaru.gol.ad.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <20150810175336.5582e9fd@batzmaru.gol.ad.jp> Sender: linux-raid-owner@vger.kernel.org To: Christian Balzer Cc: linux-raid List-Id: linux-raid.ids On Mon, 10 Aug 2015, Christian Balzer wrote: > On Mon, 10 Aug 2015 08:28:39 +0000 (UTC) Holger Kiehl wrote: > >> Hello, >> >> On Mon, 10 Aug 2015, Christian Balzer wrote: >> >>> >>> 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? >>> >> Discard for raid456 has been disabled by default because some devices in >> some cases don't do what it says on the label. >> >> You can enable it by setting the module parameter >> >> raid456.devices_handle_discard_safely=Y >> > That's what I said I did in the 2nd sentence up there. > > If it were unset, a kernel warning > "md/raid456: discard support disabled due to uncertainty." > would be issued during RAID startup/assembly. > Rigth. Sorry, I did not read your mail properly. Holger