Is it normal that write cache leads to HDDs spin up during shutdown/sleep?

[Falcosc]

I figured out that a cache flush at the shutdown/sleep process does spin up all HDDs which have write cache enabled.

 

1. Is this normal behavior, or should write cache be always empty if the disk does spin down after 10 minutes?
2. Do we already have a configuration to turn write cache off as a workaround? ([sdb...sde] in my case) Currently I use a sleep wake up script:

   printf /dev/sd%s\\n {b..e} | xargs -n 1 hdparm -W0

    

3. Would it make sense to add this workaround as an optional configuration as pull request to the s3sleep plugin or is it a bug that spin up does happen for no reason even with probably empty write cache during shutdown?

Edited June 9, 2022 by Falcosc

[Falcosc]

-K Flag to make it persistent doesn't work. It is a common issue that the write cache needs to be set manually with hdparm on every boot.

 

But I don't understand why it is disabled on some systems by default. I found people who want to disable it on every boot but also find people who asked how to enable it on every boot.

 

How did we solved it in unraid? And is the cache flush hdd spin up a bug or is disable cache workaround worth to integrate into the commuity plugins?