MySQL database restoration too slow

Question

Hello

I created a Debian 8 virtual machine on azure to test MySQL database performance.
I installed Mysql 5.5 on it (yes I know it is an old version) and i'm trying to restore a many dumps that have been done from my on-premise database server.
Total of dumps don't be large, arround 15Go, but it take 8h to restore them completely while on my on premise server it only takes 2h

I don't understand why, on this azure virtual machine I use SSD Premium while on my on-premise server I only have HDD SAS 10k. I tried to adjust the VM size but it does't change anything. At this moment I use the Standard DS3 v2

What can I do to improve my time restoration ? Does it normal that it takes long time ?
I don't understand.

Can you help me ?

Answer 1

@FlorianFavre-3809

Apologies in delayed response.

One reason for reported MySQL database restoration performance issue could be VM size causing constraints on the disks (VM & Disk configuration).

The throughput for the VM that you currently mentioned Standard_DS3_v2 has a maximum throughput of 128MBPS cached & 192 MBPS uncached. The VM might be throttling your disks which could be one reason for slow restore process.

I would recommend to resize to a larger VM that supports higher throughput of the disks and try to restore.

However, as this issue needs deeper investigation and live troubleshooting as we may need to actively check and analyzing the VM logs, to understand the exact reason for this slowness. I would recommend to open a support case so that a dedicated support engineer can work with you to narrow down on the issue.

Answer 2

@vipullag-MSFT

Thanks for your answer

I tried to change caching method on my Data disk, switch from Read/Write cache to Read Cache and the restoration took less time than before.