RE: sector size other than 512 bytes - TK (Tzung-Kwang) Wang-SSI

From: "TK (Tzung-Kwang) Wang-SSI" <tk.wang@ssi.samsung.com>
To: Sitsofe Wheeler <sitsofe@gmail.com>
Cc: "fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: RE: sector size other than 512 bytes
Date: Mon, 18 Apr 2016 20:56:22 +0000	[thread overview]
Message-ID: <6970D64051BC6047987810C1EE37A0351B698AB0@SSIEXCH-MB3.ssi.samsung.com> (raw)
In-Reply-To: <CALjAwxhktXN=-PqpebHOgq2RzhD6HrzDW101gpjArh=3J6o2pQ@mail.gmail.com>

Sitsofe,

Yes, dmesg shows "Unsupported sector size 520.". So solution for this issue is have 520-byte sector size support in linux device driver, it seems.

Regards,
TK

-----Original Message-----
From: Sitsofe Wheeler [mailto:sitsofe@gmail.com] 
Sent: Saturday, April 16, 2016 3:35 AM
To: TK (Tzung-Kwang) Wang-SSI
Cc: fio@vger.kernel.org
Subject: Re: sector size other than 512 bytes

On 15 April 2016 at 22:19, TK (Tzung-Kwang) Wang-SSI <tk.wang@ssi.samsung.com> wrote:
> That shows 512 instead of 520,
>
> # cat /sys/block/sdb/queue/logical_block_size
> 512
> # sg_readcap /dev/sdb
> Read Capacity results:
>    Last logical block address=918552575 (0x36bfffff), Number of blocks=918552576
>    Logical block length=520 bytes
> Hence:
>    Device size: 477647339520 bytes, 455520.0 MiB, 477.65 GB

In that case I'd say the issue you're seeing is within the kernel rather than in fio - the kernel block device is going to refuse userspace accesses that aren't multiples of 512. Possibly raw SCSI commands would work?

Is there anything in dmesg about "unsupported sector size" (see
https://github.com/torvalds/linux/blob/v4.5/drivers/scsi/sd.c#L2292
for the check that provokes that message)?

--
Sitsofe | http://sucs.org/~sits/