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We have database backups that we sometimes have to inject into the databases concerned. If we copy the backup to the VM hosting mysql, then we perform the import, it is very fast (3 minutes on average).

But if we import from the VM that hosts the backups to the one that hosts the mysql, the import is much longer (15 min on average).

The import uses the private network to which the VMs are connected. What is strange is that these 2 VMs are on the same VMware host. The write speed should only depend on the speed of the host disk (10 Gb / s).

So there is something blocking, but we can't seem to find what.

Please, Help!

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  • Check your MySQL database tuning parameters, in particular innodb_buffer_pool_size. If it's tiny your inserts will suffer badly.
    – tadman
    Sep 11 '20 at 9:07
  • We already raised it : innodb_buffer_pool_size = 4G And we also tried to raise open_files_limit in : open_files_limit = 1024000 as explained here : basezap.com/… But the result is the same Sep 24 '20 at 14:20
  • open_files_limit doesn't help with performance, that's more for clients + table counts. 4GB is a start. Have you tried more? Try giving it 60-80% of the available memory on your database node.
    – tadman
    Sep 24 '20 at 19:03
  • It's also worth investigating from an OS perspective here using performance monitoring tools to observe CPU load, disk IO, etc.
    – tadman
    Sep 24 '20 at 19:05

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