Hi All I'm doing some testing with OpenSUSE Leap 42.1, it ships with kernel 4.1.12 but I've also tested with 4.1.24
When I map an image with the kernel RBD client, max_sectors_kb = 127. I'm unable to increase: # echo 4096 > /sys/block/rbd0/queue/max_sectors_kb -bash: echo: write error: Invalid argument I'm seeing very poor sequential read performance which I suspect is a result of max_sectors_kb being stuck at 127 Does anyone know what's going on here? The behavior I've seen on older kernels is max_sectors_kb is set to 512 but can be increased up to max_hw_sectors_kb. On newer kernels max_sectors_kb matches the image's object size. The image is default 4MB object size, here's everything in /sys/block/rbd0/queue: # grep -r . nomerges:0 logical_block_size:512 rq_affinity:1 discard_zeroes_data:1 max_segments:128 max_segment_size:4194304 rotational:0 scheduler:none read_ahead_kb:512 max_hw_sectors_kb:4096 discard_granularity:4194304 discard_max_bytes:4194304 write_same_max_bytes:0 max_integrity_segments:0 max_sectors_kb:127 physical_block_size:512 add_random:0 nr_requests:128 minimum_io_size:4194304 hw_sector_size:512 optimal_io_size:4194304 iostats:1
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