这是我的袭击详细信息：
% sudo mdadm --detail --scan
ARRAY /dev/md/blueray-i5:0 metadata=1.2 name=blueray-i5:0 UUID=93a44fb0:9a66b691:f567475e:4a11d39a
% sudo mdadm --detail /dev/md/blueray-i5:0
/dev/md/blueray-i5:0:
Version : 1.2
Creation Time : Mon Nov 22 20:03:07 2021
Raid Level : raid0
Array Size : 7813769216 (7451.79 GiB 8001.30 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Mon Nov 22 20:03:07 2021
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : -unknown-
Chunk Size : 512K
Consistency Policy : none
Name : blueray-i5:0 (local to host blueray-i5)
UUID : 93a44fb0:9a66b691:f567475e:4a11d39a
Events : 0
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
这是我的磁盘详细信息：
% lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 232.9G 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
└─sda2 8:2 0 232.4G 0 part /run/timeshift/backup
sdb 8:16 0 3.7T 0 disk
└─sdb1 8:17 0 3.7T 0 part
└─md127 9:127 0 7.3T 0 raid0 /media/blueray/8TBRaid0
sdc 8:32 0 3.7T 0 disk
└─sdc1 8:33 0 3.7T 0 part
└─md127 9:127 0 7.3T 0 raid0 /media/blueray/8TBRaid0
sdd 8:48 0 7.3T 0 disk
└─sdd1 8:49 0 7.3T 0 part /media/blueray/WDPurple8TB
sde 8:64 0 5.5T 0 disk
└─sde1 8:65 0 5.5T 0 part /media/blueray/WDPurple6TB
% sudo hdparm -I /dev/sdb | grep Rotation (Raid0)
Nominal Media Rotation Rate: 5400
% sudo hdparm -I /dev/sdc | grep Rotation (Raid0)
Nominal Media Rotation Rate: 5400
% sudo hdparm -I /dev/sdd | grep Rotation (WDPurple8TB)
Nominal Media Rotation Rate: 7200
% sudo hdparm -I /dev/sde | grep Rotation (WDPurple6TB)
Nominal Media Rotation Rate: 5400
以下是基准：
% dd if=/dev/zero of=/media/blueray/WDPurple8TB/testfile bs=8192 count=102400 oflag=direct
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 6.42835 s, 130 MB/s
% dd if=/media/blueray/WDPurple8TB/testfile of=/dev/null bs=8192 count=102400 iflag=direct
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 6.36915 s, 132 MB/s
% dd if=/dev/zero of=/media/blueray/WDPurple6TB/testfile bs=8192 count=102400 oflag=direct
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 7.47373 s, 112 MB/s
% dd if=/media/blueray/WDPurple6TB/testfile of=/dev/null bs=8192 count=102400 iflag=direct
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 5.56981 s, 151 MB/s
% dd if=/dev/zero of=/media/blueray/8TBRaid0/testfile bs=8192 count=102400 oflag=direct
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 16.0301 s, 52.3 MB/s
% dd if=/media/blueray/8TBRaid0/testfile of=/dev/null bs=8192 count=102400 iflag=direct
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 14.5726 s, 57.6 MB/s
如您所见，我在 raid0 中有两个 4TB 5400RPM 磁盘。
所有 5 个硬盘都在同一个控制器上，但这个 raid0 的性能比我的 8TB 7200RMP 和 6TB 5400RPM 磁盘差。
为什么会发生这种情况？
更新1
我认为这个问题与缓存。
稍微改变了命令，他们给出了更容易接受的答案。请告诉我它们是否是正确的命令，或者可以进行任何修改以使命令更准确（假设我在 raid0 和单个硬盘之间没有发现任何显着的性能差异）。
% dd if=/dev/zero of=/media/blueray/8TBRaid0/testfile bs=8192 count=102400 conv=fdatasync
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 6.51745 s, 129 MB/s
% dd if=/dev/zero of=/media/blueray/WDPurple6TB/testfile bs=8192 count=102400 conv=fdatasync
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 6.02803 s, 139 MB/s
% dd if=/dev/zero of=/media/blueray/WDPurple8TB/testfile bs=8192 count=102400 conv=fdatasync
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 6.88036 s, 122 MB/s
% dd if=/media/blueray/WDPurple6TB/testfile of=/dev/null bs=8192
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 0.199695 s, 4.2 GB/s
% dd if=/media/blueray/WDPurple8TB/testfile of=/dev/null bs=8192
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 0.202408 s, 4.1 GB/s
% dd if=/media/blueray/8TBRaid0/testfile of=/dev/null bs=8192
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 0.199696 s, 4.2 GB/s