We use RAID1+0 with md on Linux (currently 2.6.37) to create an md device, then use LVM to provide volume management on top of the device, and then use ext4 as our filesystem on the LVM volume groups.
With SSDs as the drives, we'd like to see the TRIM commands propagate through the layers (ext4 -> LVM -> md -> SSD) to the devices.
It looks like recent 2.6.3x kernels have had a lot of new SSD-related TRIM support added, including lots more coverage of Device Mapper scenarios, but we still can't seem to get it to cascade down properly.
Is this possible yet? If so, how? If not, is any progress being made?