Usually Google applications uses high level network storage services like collosus, BigTable or spanner and these high level services are backed by dedicated storage appliances where they bypass the kernel for SSDs and use direct block IO for slow disks. For network, they are moving towards userspace network [1].
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BTW company-1 == Google and company-2 == FB/Meta.
In addition, Google has completely removed local storage from their servers, so there is no disk I/O at all.
What does that mean? There should be disk somewhere anyway to store gmail messages.
Usually Google applications uses high level network storage services like collosus, BigTable or spanner and these high level services are backed by dedicated storage appliances where they bypass the kernel for SSDs and use direct block IO for slow disks. For network, they are moving towards userspace network [1].
[1] https://research.google/pubs/snap-a-microkernel-approach-to-...
https://static.googleusercontent.com/media/sre.google/en//st...
It sounds a bit vanilla on paper, since things like NFS and iSCSI have existed forever.