![使用 FIO 了解 ZFS NVMe 基准测试](https://linux22.com/image/788810/%E4%BD%BF%E7%94%A8%20FIO%20%E4%BA%86%E8%A7%A3%20ZFS%20NVMe%20%E5%9F%BA%E5%87%86%E6%B5%8B%E8%AF%95.png)
我正在尝试对全 NVMe ZFS 磁盘阵列进行基准测试。我熟悉极快的基准测试结果,由于高效的 ZFS 缓存,磁盘活动很少。我遇到了相反的情况:大量的 ZFS 磁盘活动,但 FIO 仅显示很少的带宽。我该如何解释这种行为?
Zpool iostat -v 1
仅显示一秒,但每秒的输出都是一致的:16 到 20 GiB/s 的写入带宽
capacity operations bandwidth
pool alloc free read write read write
------------ ----- ----- ----- ----- ----- -----
my_pool-10 1.92T 19.0T 2 155K 95.7K 16.9G
mirror-0 329G 3.16T 0 26.2K 3.99K 2.84G
nvme2n1 - - 0 13.2K 0 1.42G
nvme3n1 - - 0 13.1K 3.99K 1.42G
mirror-1 328G 3.16T 0 26.0K 0 2.83G
nvme4n1 - - 0 13.0K 0 1.41G
nvme5n1 - - 0 13.0K 0 1.41G
mirror-2 329G 3.16T 0 25.8K 0 2.83G
nvme6n1 - - 0 12.9K 0 1.42G
nvme7n1 - - 0 12.8K 0 1.42G
mirror-3 328G 3.16T 0 25.8K 3.99K 2.81G
nvme8n1 - - 0 12.9K 3.99K 1.40G
nvme9n1 - - 0 12.9K 0 1.40G
mirror-4 328G 3.16T 0 26.0K 87.7K 2.82G
nvme10n1 - - 0 13.0K 87.7K 1.41G
nvme11n1 - - 0 13.0K 0 1.41G
mirror-5 327G 3.16T 0 25.6K 0 2.82G
nvme12n1 - - 0 12.9K 0 1.41G
nvme13n1 - - 0 12.8K 0 1.41G
------------ ----- ----- ----- ----- ----- -----
据我所知,此表中的写入统计数据翻倍。顶部的 16.9G 表示写入次数,包括所有设备上的写入次数。由于这些是镜像 vdev,因此只有一半是“数据”,另一半是冗余。显然,仍然有一些开销。从这个意义上讲,我预计我的带宽将从 16.9GB/s 降至 8.45GB/s,再降至约 6.75GB/s(20% 的开销)
另一方面,我的 FIO 基准测试显示大约 240MiB/s。要么是我不明白输出,要么是某些东西占用了我的带宽。
我运行了 25 个 4k 写入的并行作业(测试令人讨厌的网络负载)。命令如下:
sync; fio --name=asyncio --ioengine=posixaio --rw=randwrite --bs=4k --fsync=1 --size=100g --numjobs=25 --iodepth=64 --runtime=60 --time_based --filename=/my_pool-10/unbuffwrite2 --group_reporting
asyncio: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=posixaio, iodepth=64
...
fio-3.28
Starting 25 processes
asyncio: Laying out IO file (1 file / 102400MiB)
Jobs: 25 (f=25): [w(25)][100.0%][w=240MiB/s][w=61.4k IOPS][eta 00m:00s]
asyncio: (groupid=0, jobs=25): err= 0: pid=33672: Sat Aug 26 20:20:18 2023
write: IOPS=61.2k, BW=239MiB/s (251MB/s)(14.0GiB/60015msec); 0 zone resets
slat (nsec): min=90, max=5052.1k, avg=810.57, stdev=5386.98
clat (usec): min=52, max=47390, avg=9496.96, stdev=6324.85
lat (usec): min=53, max=47392, avg=9497.77, stdev=6324.94
clat percentiles (usec):
| 1.00th=[ 2442], 5.00th=[ 2835], 10.00th=[ 3195], 20.00th=[ 3785],
| 30.00th=[ 4555], 40.00th=[ 5866], 50.00th=[ 7635], 60.00th=[ 9765],
| 70.00th=[12256], 80.00th=[15139], 90.00th=[18744], 95.00th=[21890],
| 99.00th=[27395], 99.50th=[29754], 99.90th=[34341], 99.95th=[36439],
| 99.99th=[40633]
bw ( KiB/s): min=211040, max=272704, per=100.00%, avg=244851.53, stdev=462.61, samples=2975
iops : min=52760, max=68176, avg=61212.84, stdev=115.66, samples=2975
lat (usec) : 100=0.01%, 250=0.01%, 500=0.01%, 750=0.01%, 1000=0.01%
lat (msec) : 2=0.06%, 4=23.36%, 10=37.74%, 20=31.19%, 50=7.64%
fsync/fdatasync/sync_file_range:
sync (usec): min=267, max=53554, avg=16564.62, stdev=7006.70
sync percentiles (usec):
| 1.00th=[ 3589], 5.00th=[ 5145], 10.00th=[ 6849], 20.00th=[ 9896],
| 30.00th=[12518], 40.00th=[14877], 50.00th=[16909], 60.00th=[18482],
| 70.00th=[20317], 80.00th=[22414], 90.00th=[25297], 95.00th=[27919],
| 99.00th=[33817], 99.50th=[35914], 99.90th=[40109], 99.95th=[42206],
| 99.99th=[44827]
cpu : usr=0.99%, sys=0.26%, ctx=916290, majf=0, minf=702924
IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=1.9%, 16=11.8%, 32=161.4%, >=64=25.1%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=95.3%, 8=1.4%, 16=1.6%, 32=1.1%, 64=0.6%, >=64=0.0%
issued rwts: total=0,3672021,0,3683331 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=64
Run status group 0 (all jobs):
WRITE: bw=239MiB/s (251MB/s), 239MiB/s-239MiB/s (251MB/s-251MB/s), io=14.0GiB (15.0GB), run=60015-60015msec
关于我的带宽去哪儿了,您有什么见解吗?
答案1
您可能正在运行fio
数据recordsize=128k
集。读取/写入 4K 块时,您将看到高达 32 倍的 I/O 放大。
为了获得最大 IOP,您可以创建一个新的数据集并重recordsize=4k
试您的fio
工作台;然而,在现实世界中,我建议使用 16/32k 记录大小和 lz4 压缩。