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Date:      Mon, 7 Dec 2020 09:14:47 +0530
From:      Krishnamraju Eraparaju <ekraju@gmail.com>
To:        Warner Losh <imp@bsdimp.com>
Cc:        Yuri Pankov <yuripv@yuripv.dev>, FreeBSD Hackers <freebsd-hackers@freebsd.org>
Subject:   Re: when to use "/dev/nvme0ns1"
Message-ID:  <CAC-Y4SQe8a80kUxFb3W_R=%2Bc3WM005_v%2Bzss_aHGM8q5=GGJCA@mail.gmail.com>
In-Reply-To: <CANCZdfrHG=S75bFfuu5F4ezs1OJ-mS%2BDXjMGOZL5WbX4r6q9ZQ@mail.gmail.com>
References:  <CAC-Y4SRKsYspBBHHUs4dVJxAiO03FK6jfLJ23bY=vNQfUnA_qQ@mail.gmail.com> <10a5e607-a852-716a-9872-984e7247996e@yuripv.dev> <CANCZdfrHG=S75bFfuu5F4ezs1OJ-mS%2BDXjMGOZL5WbX4r6q9ZQ@mail.gmail.com>

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Thank you Warner Losh & Yuri Pankov.

Can I use nvmeXnsY for IO?
Looks like fio shows better performance with nvmeXnsY, then nvd/nda devices=
.

Thanks,
ekraju.

On Sun, Dec 6, 2020 at 11:13 AM Warner Losh <imp@bsdimp.com> wrote:

>
>
> On Sat, Dec 5, 2020 at 10:36 PM Yuri Pankov <yuripv@yuripv.dev> wrote:
>
>> Krishnamraju Eraparaju wrote:
>> > Hi All,
>> >
>> >
>> > I see there are two ways of accessing NVMe disk:
>> >     1)GEOM based: /dev/nvd0 or /dev/nda0
>> >     2)/dev/nvme0ns1
>> >
>> > When should one use " /dev/nvme0ns1"?
>>
>> See nvmecontrol(8) for the commands that operate on namespace ids.  And
>> while you could still use nvd/nda devices for those, specifying the
>> namespace explicitly could be helpful.
>>
>> An excerpt from man page:
>>
>> DEVICE NAMES
>>       Where =E2=9F=A8namespace-id=E2=9F=A9 is required, you can use eith=
er the nvmeXnsY
>>       device, or the disk device such as ndaZ or nvdZ.  The leading /dev=
/
>>       is omitted.
>>
>
> Yes. nvd* and nda* are block devices. nvme0ns1 is for administrative
> things when you may or may not have an nda/nvd device hanging around, or
> you want to deal with a specific thing and don't know the mapping to the
> nda/nvd device.
>
> Warner
>



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