Re: Western Digital Red's SMR and btrfs?

[Phil Karn <karn@ka9q.net>]

On 5/11/20 14:13, Alberto Bursi wrote:
>
> Afaik drive-managed SMR drives (i.e. all drives that disguise
> themselves as non-SMR) are acting like a SSD, writing in empty "zones"
> first and then running garbage collection later to consolidate the
> data. TRIM is used for the same reasons SSDs also use it.
> This is the way they are working around the performance penalty of
> SMR, as it's the same limitation NAND flash also has (you can write
> only a full cell at a time).
>
> See here for example
> https://support-en.wd.com/app/answers/detail/a_id/25185
>
> -Alberto

Right, I understand that (some?) SMR drives support TRIM for the same
reason that SSDs do (well, a very similar reason). My question was
whether there'd be any reason for a NON-SMR drive to support TRIM, or if
TRIM support necessarily implies shingled recording. I didn't know
shingled recording was in any general purpose 2.5" spinning laptop
drives like mine, and there's no mention of SMR in the HGST manual.

Phil