机械硬盘的出厂差异有多大？

[holinhot]

这差异有点太大了吧！！！

fio --filename=${disk} --direct=1 --rw=read --bs=64k --ioengine=libaio --iodepth=64 --runtime=300 --numjobs=4 --time_based --group_reporting --name=throughput-test-job --eta-newline=1 --readonly --output-format=json | python3 -c "import sys, json; speed=json.load(sys.stdin)['jobs'][0]['read']['bw_bytes']; speed=speed/1024/1024; print('Test Result: %s MB/s' % int(speed))"

=== /dev/sda START ===
Device Model: TOSHIBA MG09ACA18TE
Serial Number: ************
User Capacity: 18,000,207,937,536 bytes [18.0 TB]
Rotation Rate: 7200 rpm
Form Factor: 3.5 inches
SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Test Result: 235 MB/s
=== /dev/sda END ===

=== /dev/sdb START ===
Device Model: TOSHIBA MG09ACA18TE
Serial Number: ************
User Capacity: 18,000,207,937,536 bytes [18.0 TB]
Rotation Rate: 7200 rpm
Form Factor: 3.5 inches
SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Test Result: 244 MB/s
=== /dev/sdb END ===

=== /dev/sdc START ===
Device Model: TOSHIBA MG09ACA18TE
Serial Number: ************
User Capacity: 18,000,207,937,536 bytes [18.0 TB]
Rotation Rate: 7200 rpm
Form Factor: 3.5 inches
SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Test Result: 200 MB/s
=== /dev/sdc END ===

=== /dev/sdd START ===
Device Model: TOSHIBA MG09ACA18TE
Serial Number: ************
User Capacity: 18,000,207,937,536 bytes [18.0 TB]
Rotation Rate: 7200 rpm
Form Factor: 3.5 inches
SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Test Result: 202 MB/s
=== /dev/sdd END ===

[felixcode]

机械磁盘外圈和内圈的读取线速度不一样。

[holinhot]

@felixcode 能不能对齐到相同位置测试

[felixcode]

@holinhot
不知道，找了下没找到

[msg7086]

@felixcode 每块盘建个小分区来测不就行了……

[msg7086]

https://vip2.loli.io/2021/04/29/DOteY1xS7ifVv3q.png
读写位置对测试结果影响很大的。

[felixcode]

@msg7086
嗯，是个办法，但得是空盘啊

[holinhot]

@msg7086 目前裸盘测试的，/dev/sda 这样。没有分区

[msg7086]

@holinhot 建议分个区，盘头分 100G 出来，然后在分区上测。

[holinhot]

@msg7086 建了一个 100G 的分区来测试。发现后面两个盘还是只有 200MB/s 左右，尝试把盘位调换了一下，看来是放到后两个盘位的硬盘速度比较慢。