Even worse, dm-linear has the same problem. dm-linear over mdadm RAID5 doesn't support discard while mdadm device itself supports it.
> Hi! > > A dm-era device created over a RAID5 array loses discard support. > > Test script is attached. > > If you run it on SSD you'll see something like: > > loop0 4096 > loop1 4096 > loop2 4096 > loop3 4096 > md55 1048576 > loop_test_era 0 > > I.e. mdadm device supports discard, but dm-era device started over it doesn't. > > If you create a dm-era device over a normal block device without mdadm RAID5 > or even over mdadm > RAID1 - it will preserve discard support. > > Why? How can it be fixed? > > -- > With best regards, > Vitaliy Filippov > > -- > dm-devel mailing list > dm-devel@redhat.com > https://listman.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
