From: Alberto Bursi <bobafetthotmail@gmail.com>
To: Phil Karn <karn@ka9q.net>,
Zygo Blaxell <ce3g8jdj@umail.furryterror.org>,
Steven Fosdick <stevenfosdick@gmail.com>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
Rich Rauenzahn <rrauenza@gmail.com>
Subject: Re: Western Digital Red's SMR and btrfs?
Date: Mon, 11 May 2020 23:13:19 +0200 [thread overview]
Message-ID: <69847faf-5fb3-9eac-b819-373a0f814044@gmail.com> (raw)
In-Reply-To: <bb237d74-49ab-27e0-0286-5bdd880dd2cb@ka9q.net>
On 11/05/20 22:35, Phil Karn wrote:
> On 5/10/20 22:06, Zygo Blaxell wrote:
>>
>> The exceptions would be data extents that are explicitly deleted
>> (TRIM command), and it looks like a sequential overwrite at the _end_
>> of a zone (i.e. starting in the middle on a sector boundary and writing
>
>
> Do these SMR drives generally support TRIM? What other spinning drives
> support it?
>
> I was surprised to recently discover a spinning drive that supports
> TRIM. It's a HGST Z5K1 2.5" 5400 RPM 1TB OEM drive I pulled from an ASUS
> laptop to replace with a SSD. TRIM support is verified by hdparm and by
> running the fstrim command. There's nothing in the literature about this
> being a hybrid drive.
>
> Doesn't seem likely, but could it be shingled?
>
> Phil
>
>
>
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
next prev parent reply other threads:[~2020-05-11 21:13 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-02 5:24 Western Digital Red's SMR and btrfs? Rich Rauenzahn
2020-05-04 23:08 ` Zygo Blaxell
2020-05-04 23:24 ` Chris Murphy
2020-05-05 2:00 ` Zygo Blaxell
2020-05-05 2:22 ` Chris Murphy
2020-05-05 3:26 ` Zygo Blaxell
2020-05-09 21:00 ` Phil Karn
2020-05-09 21:46 ` Steven Fosdick
2020-05-11 5:06 ` Zygo Blaxell
2020-05-11 20:35 ` Phil Karn
2020-05-11 21:13 ` Alberto Bursi [this message]
2020-05-11 22:42 ` Phil Karn
2020-05-12 0:12 ` Zygo Blaxell
2020-05-12 2:17 ` Alberto Bursi
2020-05-11 4:06 ` Damien Le Moal
2020-05-05 9:30 ` Dan van der Ster
-- strict thread matches above, loose matches on Subject: below --
2020-05-02 12:26 Torstein Eide
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