Re: In-Place Upgrade from MySQL 5.7.33 to MySQL 8.0.25 very slow

[Ralf Meyer]

Dear Frederic,

Thank you for your answer! :)

Read speeds:
$ hdparm -tT --direct /dev/sda

/dev/sda:
Timing O_DIRECT cached reads: 1644 MB in 2.00 seconds = 822.47 MB/sec
Timing O_DIRECT disk reads: 2612 MB in 3.00 seconds = 870.41 MB/sec

Write speeds:
$ dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
1024+0 Datensätze ein
1024+0 Datensätze aus
1073741824 Bytes (1,1 GB, 1,0 GiB) kopiert, 2,21399 s, 485 MB/s

That looks pretty good in my opinion. We unfortunately had this issue on several systems with similar specs, so I doubt that it is an I/O issue.

The mysql.idb has 276 MB in this case after the upgrade has finished.

I do have another idea, though: Could this possibly be related to a too low value for innodb_open_files? We had an issue with this on another in-place upgrade.

We will probably perform a dump on a database where we expect this to occur on upgrade again and run some tests on it on a seperate system.

I am open for any ideas. Thanks a lot for your help, I highly appriciate it.

Kind regards,
Ralf