因此，提供商为我们提供了 500 IOPS/TB 作为其在 VMWare 和 RAID5-SAN 环境中的磁盘性能的 SLA 标准。这显然是通过以下方式衡量的：
- 平均传输块大小为 16kB
- 读写比为 3:1
- 多线程 IO 操作
- 80% 随机 IO 建模
- 读取缓存命中率为 20%
我想要做的是确定任何特定的 Linux VM 是否获得了这种性能，然后与其他提供商运行相同的基准测试，以便进行比较。
环顾四周，似乎菲奥是衡量上述内容的最可配置的。到目前为止，我得到的配置是：
[global]
blocksize=16k
rwmixread=75 # 3:1 read:write ratio
ramp_time=30
runtime=600
time_based
buffered=1
# size = free-ram * 80% / 5
# so we get a ~20% cache hit across the 5x processes
# this is for an 8GB ram host with 7.3GB free after buffers/cache
size=1180m
# create a mix to get to 80% random reads
# also means we'll be doing at least 5x IO operations in parallel
[sla-0]
readwrite=randrw:2
[sla-1]
readwrite=randrw:2
[sla-2]
readwrite=randrw
[sla-3]
readwrite=randrw
[sla-4]
readwrite=randrw
有改进建议吗？使用buffered默认设置是ioengine最好的方法吗？
如果我在一台空闲的 4x 虚拟核心机器上运行此程序，该机器具有 8GB RAM 和 470GB 的分配存储空间，我预计通过上述方法可获得 235 IOPS（500 * 0.47）。我得到的结果是：
sla-0: (g=0): rw=randrw, bs=16K-16K/16K-16K, ioengine=sync, iodepth=2
sla-1: (g=0): rw=randrw, bs=16K-16K/16K-16K, ioengine=sync, iodepth=2
sla-2: (g=0): rw=randrw, bs=16K-16K/16K-16K, ioengine=sync, iodepth=2
sla-3: (g=0): rw=randrw, bs=16K-16K/16K-16K, ioengine=sync, iodepth=2
sla-4: (g=0): rw=randrw, bs=16K-16K/16K-16K, ioengine=sync, iodepth=2
Starting 5 processes
sla-0: Laying out IO file(s) (1 file(s) / 1180MB)
sla-1: Laying out IO file(s) (1 file(s) / 1180MB)
sla-2: Laying out IO file(s) (1 file(s) / 1180MB)
sla-3: Laying out IO file(s) (1 file(s) / 1180MB)
sla-4: Laying out IO file(s) (1 file(s) / 1180MB)
Jobs: 5 (f=5): [mmmmm] [100.0% done] [5931K/1966K /s] [362/120 iops] [eta 00m:00s]
sla-0: (groupid=0, jobs=1): err= 0: pid=16701
read : io=1086MB, bw=1853KB/s, iops=115, runt=600003msec
clat (usec): min=4, max=1771K, avg=8607.53, stdev=22114.44
bw (KB/s) : min= 0, max= 4087, per=24.44%, avg=1914.96, stdev=1130.29
write: io=372416KB, bw=635586B/s, iops=38, runt=600003msec
clat (usec): min=6, max=2574, avg=57.38, stdev=79.65
bw (KB/s) : min= 0, max=11119, per=26.07%, avg=679.63, stdev=517.84
cpu : usr=0.08%, sys=0.63%, ctx=64513, majf=0, minf=109
IO depths : 1=107.4%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
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=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
issued r/w: total=69474/23276, short=0/0
lat (usec): 10=10.23%, 20=8.89%, 50=4.15%, 100=11.66%, 250=0.83%
lat (usec): 500=1.48%, 750=1.41%, 1000=0.82%
lat (msec): 2=0.83%, 4=1.56%, 10=47.07%, 20=5.91%, 50=4.24%
lat (msec): 100=0.55%, 250=0.29%, 500=0.06%, 750=0.01%, 1000=0.01%
lat (msec): 2000=0.01%
sla-1: (groupid=0, jobs=1): err= 0: pid=16702
read : io=963360KB, bw=1605KB/s, iops=100, runt=600180msec
clat (usec): min=4, max=2396K, avg=9934.23, stdev=30986.37
bw (KB/s) : min= 0, max= 4657, per=21.64%, avg=1695.89, stdev=1273.00
write: io=326000KB, bw=556206B/s, iops=33, runt=600180msec
clat (usec): min=6, max=3882, avg=55.07, stdev=77.92
bw (KB/s) : min= 0, max=10708, per=23.74%, avg=618.92, stdev=559.01
cpu : usr=0.08%, sys=0.53%, ctx=55500, majf=0, minf=129
IO depths : 1=108.5%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
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=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
issued r/w: total=60210/20375, short=0/0
lat (usec): 10=11.36%, 20=9.63%, 50=3.56%, 100=11.97%, 250=0.81%
lat (usec): 500=0.66%, 750=0.50%, 1000=0.37%
lat (msec): 2=0.33%, 4=0.74%, 10=49.56%, 20=3.78%, 50=5.48%
lat (msec): 100=0.60%, 250=0.43%, 500=0.16%, 750=0.04%, 1000=0.01%
lat (msec): 2000=0.01%, >=2000=0.01%
sla-2: (groupid=0, jobs=1): err= 0: pid=16703
read : io=827584KB, bw=1379KB/s, iops=86, runt=600012msec
clat (usec): min=397, max=2396K, avg=11569.59, stdev=31237.03
bw (KB/s) : min= 0, max= 4237, per=18.60%, avg=1457.59, stdev=1113.89
write: io=276192KB, bw=471358B/s, iops=28, runt=600012msec
clat (usec): min=8, max=8339, avg=63.95, stdev=121.52
bw (KB/s) : min= 0, max= 8531, per=20.52%, avg=534.85, stdev=478.91
cpu : usr=0.07%, sys=0.54%, ctx=57019, majf=0, minf=89
IO depths : 1=109.9%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
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=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
issued r/w: total=51724/17262, short=0/0
lat (usec): 10=0.98%, 20=5.38%, 50=3.53%, 100=13.68%, 250=0.92%
lat (usec): 500=0.60%, 750=0.39%, 1000=0.22%
lat (msec): 2=0.24%, 4=2.26%, 10=59.15%, 20=4.90%, 50=6.28%
lat (msec): 100=0.78%, 250=0.48%, 500=0.18%, 750=0.03%, 1000=0.01%
lat (msec): 2000=0.01%, >=2000=0.01%
sla-3: (groupid=0, jobs=1): err= 0: pid=16704
read : io=865920KB, bw=1443KB/s, iops=90, runt=600005msec
clat (usec): min=369, max=2396K, avg=11052.97, stdev=32396.85
bw (KB/s) : min= 0, max= 5984, per=19.47%, avg=1525.97, stdev=1164.42
write: io=285568KB, bw=487365B/s, iops=29, runt=600005msec
clat (usec): min=7, max=11910, avg=65.72, stdev=154.09
bw (KB/s) : min= 0, max=11064, per=21.38%, avg=557.30, stdev=534.59
cpu : usr=0.07%, sys=0.57%, ctx=59458, majf=0, minf=109
IO depths : 1=109.5%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
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=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
issued r/w: total=54120/17848, short=0/0
lat (usec): 10=0.99%, 20=5.11%, 50=3.58%, 100=13.64%, 250=0.89%
lat (usec): 500=0.71%, 750=0.48%, 1000=0.30%
lat (msec): 2=0.70%, 4=4.00%, 10=57.63%, 20=5.21%, 50=5.40%
lat (msec): 100=0.70%, 250=0.43%, 500=0.16%, 750=0.03%, 1000=0.01%
lat (msec): 2000=0.01%, >=2000=0.01%
sla-4: (groupid=0, jobs=1): err= 0: pid=16705
read : io=934752KB, bw=1558KB/s, iops=97, runt=600007msec
clat (usec): min=187, max=2396K, avg=10236.87, stdev=26080.98
bw (KB/s) : min= 0, max=11419, per=20.74%, avg=1625.28, stdev=1338.26
write: io=304528KB, bw=519721B/s, iops=31, runt=600007msec
clat (usec): min=7, max=7572, avg=67.29, stdev=117.27
bw (KB/s) : min= 0, max=10772, per=22.06%, avg=575.17, stdev=560.68
cpu : usr=0.08%, sys=0.60%, ctx=63685, majf=0, minf=129
IO depths : 1=108.7%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
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=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
issued r/w: total=58422/19033, short=0/0
lat (usec): 10=0.81%, 20=4.77%, 50=3.62%, 100=13.77%, 250=0.97%
lat (usec): 500=1.45%, 750=0.64%, 1000=0.53%
lat (msec): 2=1.75%, 4=4.71%, 10=53.48%, 20=6.92%, 50=5.53%
lat (msec): 100=0.56%, 250=0.37%, 500=0.08%, 750=0.02%, 1000=0.01%
lat (msec): 2000=0.01%, >=2000=0.01%
Run status group 0 (all jobs):
READ: io=4593MB, aggrb=7836KB/s, minb=1412KB/s, maxb=1897KB/s, mint=600003msec, maxt=600180msec
WRITE: io=1528MB, aggrb=2607KB/s, minb=471KB/s, maxb=635KB/s, mint=600003msec, maxt=600180msec
Disk stats (read/write):
dm-0: ios=298995/596154, merge=0/0, ticks=3107720/433061790, in_queue=436170340, util=99.68%, aggrios=0/0, aggrmerge=0/0, aggrticks=0/0, aggrin_queue=0, aggrutil=0.00%
sdb: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=-nan%
汇总每个作业的读取和写入 IOPS（为什么 fio 没有将其包含在摘要中？）我得到 647，这似乎超出了他们指定的服务水平。我遗漏了什么明显的信息，或者他们的指标在某些工作负载方面存在严重偏差（特别是我对具有数据仓库工作负载的 PostgreSQL 感兴趣）。
答案1
SQL 和数据仓库更像是 8:1 的读取与写入，全是小块，全是随机的。无论如何，除了随机读取之外的任何内容都很容易缓存，并且不太可能导致磁盘性能问题。如果不知道他们如何处理磁盘，很难真正提供太多帮助，但可以考虑询问他们指定“RAID5-SAN 环境”时的意思。
由于他们将 SLA 指定为每 TB 的 IOPS，我大胆猜测他们提供给您的每个卷都应该位于单独的 RAID-5 上，以便在添加卷时提供更多的 IOPS。糟糕的性能很容易由糟糕的 raid 邻居造成：与您在同一个 raid 上的卷占用了超过其应有份额的存储资源。这样做的问题是，有时您的 SLA 会被超出，但有时您必须处理高延迟。
首先警告他们您对性能不满意，他们可能会简单地将您转移到利用率较低的 raid，这可能会解决您的所有问题。 还要询问他们是否有一些可用的 raid-10 存储，也许要求在那里而不是 raid 5 上放置一个卷。 如果问题再次出现，那么请考虑获取您自己的存储或寻找可以为您提供更好性能的其他主机。