Linux中遇到磁盤寫性能很差

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

                                              ------->此處說明write cache被關閉

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

                                              ------->這是希望的:此處說明write cache被打開