我在 ESXi 7.0U3g 主机上运行了两个虚拟机。
两个虚拟机都安装在 NVMe 数据存储上（供下面的比较参考，请注意“usbspeed”与“nvmespeed”测试），并且具有相同的配置：
- CPU：8
- 内存：16GB
- SCSI 控制器：LSI Logic Parallel
- USB 控制器：USB 3.1
虚拟机＃1：Debian 11.4.0（5.10.0-18-amd64）
# dmesg | grep usb
[237086.992370] usb 2-1: new SuperSpeed Gen 1 USB device number 2 using xhci_hcd
[237087.013420] usb 2-1: New USB device found, idVendor=1058, idProduct=264d, bcdDevice=30.12
[237087.013422] usb 2-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[237087.013423] usb 2-1: Product: easystore 264D
[237087.013424] usb 2-1: Manufacturer: Western Digital
[237087.013425] usb 2-1: SerialNumber: [redacted]
[237087.046318] usb-storage 2-1:1.0: USB Mass Storage device detected
[237087.046483] scsi host33: usb-storage 2-1:1.0
[237087.046547] usbcore: registered new interface driver usb-storage
[237087.048081] usbcore: registered new interface driver uas
# lsusb -t
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
|__ Port 1: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
|__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 12M
# lspci | grep -i usb
13:00.0 USB controller: VMware USB3 xHCI 1.0 Controller
# dd if=/dev/zero of=/mnt/easystore/usbspeed bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.84469 s, 157 MB/s
# dd if=/dev/zero of=/nvmespeed bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.664862 s, 1.6 GB/s
# sysctl -a | grep -i dirty
vm.dirty_background_bytes = 0
vm.dirty_background_ratio = 10
vm.dirty_bytes = 0
vm.dirty_expire_centisecs = 3000
vm.dirty_ratio = 20
vm.dirty_writeback_centisecs = 500
vm.dirtytime_expire_seconds = 43200
# cat /sys/block/sdb/queue/scheduler
[mq-deadline] none
虚拟机＃2：Ubuntu 22.04.1（5.15.0-43-generic）
# dmesg | grep usb
[ 8175.488648] usb 2-1: new SuperSpeed USB device number 2 using xhci_hcd
[ 8175.509805] usb 2-1: New USB device found, idVendor=1058, idProduct=264d, bcdDevice=30.12
[ 8175.509808] usb 2-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 8175.509810] usb 2-1: Product: easystore 264D
[ 8175.509811] usb 2-1: Manufacturer: Western Digital
[ 8175.509812] usb 2-1: SerialNumber: [redacted]
[ 8175.540057] usb-storage 2-1:1.0: USB Mass Storage device detected
[ 8175.540532] scsi host33: usb-storage 2-1:1.0
[ 8175.541089] usbcore: registered new interface driver usb-storage
[ 8175.542779] usbcore: registered new interface driver uas
# lsusb -t
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
|__ Port 1: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
|__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 12M
# lspci | grep -i usb
0b:00.0 USB controller: VMware USB3 xHCI 1.0 Controller
# dd if=/dev/zero of=/mnt/easystore/usbspeed bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.567066 s, 1.9 GB/s
# dd if=/dev/zero of=/nvmespeed bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.636782 s, 1.7 GB/s
# sysctl -a | grep -i dirty
vm.dirty_background_bytes = 0
vm.dirty_background_ratio = 10
vm.dirty_bytes = 0
vm.dirty_expire_centisecs = 3000
vm.dirty_ratio = 20
vm.dirty_writeback_centisecs = 500
vm.dirtytime_expire_seconds = 43200
# cat /sys/block/sdb/queue/scheduler
[mq-deadline] none
我已经多次运行相同的测试并且每次都得到类似的结果，所以它不像一次性或缓存相关的事情。
为什么 Debian 写入 USB3 磁盘时速度这么慢？
- 编辑 1：添加了来自
lsusb -t - 编辑 2：添加了来自
lspci | grep -i usb sysctl -a | grep -i dirty编辑 3：根据 @gapsf 的评论添加输出cat /sys/block/sdb/queue/scheduler编辑 4：根据 @gapsf 的评论添加输出