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

[Tim Walker <tim.t.walker@seagate.com>]

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