My ZFS pool is set up as a raidz2 pool as follows:
The six disks are connected to an on board SAS2008 HBA, using the mps() driver, while the log is connected to an ahci() interface.
Recently, I tried to write a DTrace script to measure disk IOs. I found out that whenever there were sync writes, the ahci driver would send 1 sync command to the drive, while the mps driver would send 2 sync commands to each drives in the pool increasing the latencies of the disks significantly. My question is, should this be considered a bug of the mps driver and report it?
Code:
NAME STATE READ WRITE CKSUM
myzfs ONLINE 0 0 0
raidz2-0 ONLINE 0 0 0
gpt/akjc ONLINE 0 0 0
gpt/0773 ONLINE 0 0 0
gpt/6062 ONLINE 0 0 0
gpt/2651 ONLINE 0 0 0
gpt/gvkc ONLINE 0 0 0
gpt/ja7h ONLINE 0 0 0
logs
gpt/log0 ONLINE 0 0 0
The six disks are connected to an on board SAS2008 HBA, using the mps() driver, while the log is connected to an ahci() interface.
Recently, I tried to write a DTrace script to measure disk IOs. I found out that whenever there were sync writes, the ahci driver would send 1 sync command to the drive, while the mps driver would send 2 sync commands to each drives in the pool increasing the latencies of the disks significantly. My question is, should this be considered a bug of the mps driver and report it?