Why does "fio write" change the performance of "fio read"

[YLin34]

I have a P4600 2TB NVMe SSD. Right after I used Intel SSD toolbox to secure erase it, fio reports 4kB random read at 809K IOPS.

sudo fio --name=dummy --size=10G --filename=/dev/nvme0n1 --ioengine=libaio --direct=1 --rw=randread -bs=4k** --iodepth=64 --numjobs=4 --group_reporting

However, after I tried to pre-conditioning the SSD with the following write command

sudo fio --name=dummy --size=2000G --filename=/dev/nvme0n1 --ioengine=libaio --direct=1 --rw=write -bs=4k** --iodepth=64 --numjobs=1 --group_reporting (I also tried --size=1700G, the result is the same)

the randread command above is now reporting 4kB at 520k IOPS.

So why such a severe drop?

[idata]

Hi yaolin,

We would like to let you know that this process can affect the sequential and random reads as well. Also, several factors can affect the score:

• Processor Performance
• Platform Performance
• I/O and Peripheral Performance

You can check the following http://manuals.ts.fujitsu.com/file/12176/fujitsu_intel-ssd-dc-pcie-eg-en.pdf evaluation guide for the Intel® SSD DC P3700 Series, this does not apply to your SSD but the terminology is the same.

Regards,

Junior M.

[idata]

Hi yaolin,

We would like to know if you read our previous post. If you have any other questions, we'll be waiting for your response.Regards, Junior M.