Linux中遇到磁盘写性能很差

https://access.redhat.com/solutions/77123


If it is a raid disk, check if write cache is enabled. Check for following messages in dmesg
sd 4:2:0:0: [sda] Write cache: disabled, read cache: enabled, supports DPO and FUA
sd 4:2:1:0: [sdb] Write cache: disabled, read cache: enabled, supports DPO and FUA
sd 4:2:2:0: [sdc] Write cache: disabled, read cache: enabled, supports DPO and FUA
                                              ------->此处说明write cache被关闭
      
versus expetected:

Raw
sd 4:2:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
sd 4:2:1:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
sd 4:2:2:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
                                              ------->这是希望的:此处说明write cache被打开