I'm surprised (and shocked) that letting unencrypted data hit the disk is still common enough to make such optimizations worth it.
Even if you just stick the key in the server's TPM without any sealing, an encrypted disk makes it much easier to deal with e.g. drive returns (for warranty or fault analysis) or disposal.
There's very, very little benefit in encrypting data at a filesystem level in a datacenter if you think about it.
And unfortunately compression and encryption are seemingly at odds fundamentally :c
"Even if you just stick the key in the server's TPM without any sealing, an encrypted disk makes it much easier to deal with e.g. drive returns (for warranty or fault analysis) or disposal."
Would you resell usable drives that you no longer want to use (e.g. because they're too small or your needs changed more towards SSDs) if unencrypted data was written to them at some point?
How much effort would you put into making sure that no broken drive that can't be wiped leaves the datacenter without shredding?
Any process you put in place will have gaps - e.g. through human error or malicious acts - and this provides pretty solid protection against that.
Bitlocker supports on drive hardware encryption, and I'd be surprised if other major file systems didn't.
If I recall, it's a FIPS requirement for data at rest now.
Because the storage hardware might be loyal to someone who is not the owner of the data.
Because the hardware cannot be trusted to do it correctly. IIRC Bitlocker stopped relying on it for this reason.
https://www.howtogeek.com/fyi/you-cant-trust-bitlocker-to-en... (see the updates)