Re: [LSF/MM/BPF TOPIC] durability vs performance for flash devices (especially embedded!)

Hi all-

On  Wednesday, June 9, 2021 at 9:20:52 PM Ric Wheeler wrote:

On 6/9/21 2:47 PM, Bart Van Assche wrote:

quoted

On 6/9/21 11:30 AM, Matthew Wilcox wrote:

quoted

maybe you should read the paper.

" Thiscomparison demonstrates that using F2FS, a flash-friendly file
sys-tem, does not mitigate the wear-out problem, except inasmuch asit
inadvertently rate limitsallI/O to the device"

It seems like my email was not clear enough? What I tried to make clear
is that I think that there is no way to solve the flash wear issue with
the traditional block interface. I think that F2FS in combination with
the zone interface is an effective solution.

What is also relevant in this context is that the "Flash drive lifespan
is a problem" paper was published in 2017. I think that the first
commercial SSDs with a zone interface became available at a later time
(summer of 2020?).

Bart.

Just to address the zone interface support, it unfortunately takes a very long 
time to make it down into the world of embedded parts (emmc is super common and 
very primitive for example). UFS parts are in higher end devices, have not had a 
chance to look at what they offer.

Ric

For zoned block devices, particularly the sequential write zones, maybe it makes more sense for the device to manage wear leveling on a zone-by-zone basis. It seems like it could be pretty easy for a device to decide which head/die to select for a given zone when the zone is initially opened after the last reset write pointer.

Best regards,
-Tim