Any chance you could explain why ... ?

[Roger Sewell]

Hello,

I have observed some behaviour I don't understand using grub2
1:2.06-46.el9.rocky.0.1 and two different disk drives, and wonder
whether you are able to educate me as to why this might be happening.

One drive is a Western Digital Blue WD5000LPCX 500 GB SATA3 5400 rpm
6 GB/s laptop drive with 16 GB cache, which I will call the "slow" drive.

The other is a much older Savvio 10K5 ST9800605SS 300 GB SAS 10000 rpm
6 GB/s server drive with 64 GB cache, which I will call the "fast" drive.

When booting Rocky Linux 9.1 from the slow drive it takes about 70
seconds longer than from the fast drive.

On investigation, using separate grub commands from the grub shell,
almost the entire extra time is taken in the initrd command. However,
what I totally don't understand is that the time during which the drive
activity light is on (during the initrd command) is the same with the
fast drive and the slow drive - about one second in both cases.

Why should it then take a further 69 seconds if the initramfs file has
been loaded from the slow drive compared with if it has been loaded from
the fast drive ?

This has me totally mystified - any light you can shed would be
extremely welcome.

With thanks in advance,
Roger Sewell.