MySQL slow importing on hyper-v virtual server compared to host

Question

Database dump file:

• 6 MB size
• 14k rows
• 10 tables

Server specs (Ubuntu 20.04, virtual (hyper-v)):

• OS: Ubuntu 20.04.1 LTS
• MySQL version: Ver 8.0.21-0ubuntu0.20.04.4 for Linux on x86_64 ((Ubuntu))
• 4 core, 2 GB RAM
• 100 GB storage

Host MySQL

• Windows server
• MySQL version: 8.0.17 - MySQL Community Server - GPL
• HDD Storage
• 8 GB RAM

Importing dump to the database on the host machine took 1-3 seconds, importing on the guest server 5-6 minutes.

iotop reports maximum write speed 5 MB/s while importing.

Refreshing database on phpmyadmin, i can see all row is imported after 1 minutes, the rest of the time is just altering table:

ALTER TABLE `table`
   MODIFY `ID` int NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=7;

Import command:

mysql -u user -p db < /home/user/dump.sql

tried:

• mysql-server reinstall on guest machine
• disable unique checks with UNIQUE_CHECKS=0;
• disable foreign key checks with FOREIGN_KEY_CHECKS=0;

Answer 1

Turning on: "Turn off Windows write-cache buffer" solved the issue for me. (no restart required for me)

Benchmark write speed, before and after the setting.

dd if=/dev/zero of=/tmp/test2.img bs=512 count=1000 oflag=dsync

Answer 2

Test SSD speed to see if that's the problem

Follow this guide:

dd if=/dev/zero of=/tmp/test2.img bs=512 count=1000 oflag=dsync

For me (Samsung evo 860 SSD) the results before the fix were around 80 kB/s.

Fix SSD speed if it's slow

Follow this guide. One of the fixes suggested is to trim all SSDs:

sudo fstrim -av

You will it trim the amount equal to the free space on your disk. Follow up by rebooting the system

After reboot, my writespeeds were up to 280 kB/s, and mysql import was at a normal speed again.