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. Christian > Ensure that your drives can handle discard safely. > > Regards, > Holger > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Christian Balzer Network/Systems Engineer chibi@xxxxxxx Global OnLine Japan/Fusion Communications http://www.gol.com/ -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
