On Mon, Mar 25, 2024 at 02:53:56PM +0100, Pankaj Raghav wrote: > This is an excellent question that needs a bit of community discussion to > expose a device agnostic value that userspace can trust. > > There might be a talk this year at LSFMM about untorn writes[1] in buffered IO > path. I will make sure to bring this question up. > > At the moment, Linux exposes the physical blocksize by taking also atomic > guarantees > into the picture, especially for NVMe it uses the NAWUPF and AWUPF while > setting > physical blocksize (/sys/block/<dev>/queue/physical_block_size). > > A system admin could use value exposed by phy_bs as a hint to disable > full_page_write=off. > Of course this requires also the device to give atomic guarantees. > > The most optimal would be DB page size == FS block size == Device atomic size.
One other thing I remember is that some people modified the ZFS file system parameters enough that they made Postgres non-durable and corrupted their database. This is a very hard thing to get right because the user has very little feedback when they break things. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com Only you can decide what is important to you.
