Re: [LSF/MM/BPF TOPIC] Large block for I/O

Matthew Wilcox
2023-12-22T05:13:57Z

On Thu, Dec 21, 2023 at 12:33:08PM -0800, Bart Van Assche wrote:
> I'm interested in this topic. But I'm wondering whether the disadvantages of
> large blocks will be covered? Some NAND storage vendors are less than
> enthusiast about increasing the logical block size beyond 4 KiB because it
> increases the size of many writes to the device and hence increases write
> amplification.

I've been mulling this over for a few hours and I don't really understand
it. The push for larger block sizes is coming from (some) storage
vendors. If it doesn't make sense for (other) storage vendors, they
don't have to do it. Just like nobody is forced to ship shingled drives,
or vertical NAND or four-bit-per-cell or fill their drives with helium.
Vendors do it if it makes sense for them, and don't if it doesn't.

It clearly solves a problem (and the one I think it's solving is the
size of the FTL map). But I can't see why we should stop working on it,
just because not all drive manufacturers want to support it.