3.10: discard/trim support on md-raid1?

[Justin Piszcz]

Hello,

Running 3.10 and I see the following for an md-raid1 of two SSDs:

Checking /sys/block/md1/queue:
add_random: 0
discard_granularity: 512
discard_max_bytes: 2147450880
discard_zeroes_data: 0
hw_sector_size: 512
iostats: 0
logical_block_size: 512
max_hw_sectors_kb: 32767
max_integrity_segments: 0
max_sectors_kb: 512
max_segment_size: 65536
max_segments: 168
minimum_io_size: 512
nomerges: 0
nr_requests: 128
optimal_io_size: 0
physical_block_size: 512
read_ahead_kb: 8192
rotational: 1
rq_affinity: 0
scheduler: none
write_same_max_bytes: 0

What should be seen:
rotational: 0
And possibly:
discard_zeroes_data: 1

Can anyone confirm if there is a workaround to allow TRIM when using
md-raid1?

Some related discussion here:
http://us.generation-nt.com/answer/md-rotational-attribute-help-206571222.ht
ml
http://www.progtown.com/topic343938-ssd-strange-itself-conducts.html


Justin.


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