Re: SATA hdd refuses to reallocate a sector?

From: Mark Lord <mlord@pobox.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Marcus Overhagen <marcus.overhagen@gmail.com>,
	kernel list <linux-kernel@vger.kernel.org>,
	linux-ide@vger.kernel.org, tj@kernel.org
Subject: Re: SATA hdd refuses to reallocate a sector?
Date: Sun, 23 Jun 2013 17:27:52 -0400	[thread overview]
Message-ID: <51C76858.4060906@pobox.com> (raw)
In-Reply-To: <20130623190003.GA6714@amd.pavel.ucw.cz>

On 13-06-23 03:00 PM, Pavel Machek wrote:
>
> Thanks for the hint. (Insert rant about hdparm documentation
> explaining that it is bad idea, but not telling me _why_ is it bad
> idea. Can I expect cache consistency issues after that, or is it just
> simple "you are writing to the disk without any checks"? Plus, I guess
> documentation should mention what sector number is. I guess sectors
> are 512bytes for the old drives, but is it 512 or 4096 for new
> drives?)

For ATA, use the "logical sector size".
For all existing drives out there, that's a 512 byte unit.

> ...but it does not do the trick :-(. It behaves strangely as if it was
> still cached somewhere. Do I need to turn off the write back cache?

No, it works just fine.  You probably have more than one bad sector.
After you see a read failure, run "smartctl -a" and look at the error
logs to see what sector the drive is choking on.

Or just low-level format it all with "hdparm --security-erase".

Cheers
-- 
Mark Lord
Real-Time Remedies Inc.
mlord@pobox.com