From owner-freebsd-fs@freebsd.org  Wed Oct 19 07:22:22 2016
Return-Path: <owner-freebsd-fs@freebsd.org>
Delivered-To: freebsd-fs@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id E5BC2C16FFE
 for <freebsd-fs@mailman.ysv.freebsd.org>; Wed, 19 Oct 2016 07:22:22 +0000 (UTC)
 (envelope-from phk@phk.freebsd.dk)
Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222])
 by mx1.freebsd.org (Postfix) with ESMTP id B226EA31
 for <freebsd-fs@freebsd.org>; Wed, 19 Oct 2016 07:22:22 +0000 (UTC)
 (envelope-from phk@phk.freebsd.dk)
Received: from critter.freebsd.dk (unknown [192.168.55.3])
 by phk.freebsd.dk (Postfix) with ESMTP id 650112740A;
 Wed, 19 Oct 2016 07:22:21 +0000 (UTC)
Received: from critter.freebsd.dk (localhost [127.0.0.1])
 by critter.freebsd.dk (8.15.2/8.15.2) with ESMTP id u9J7MICW007925;
 Wed, 19 Oct 2016 07:22:20 GMT (envelope-from phk@phk.freebsd.dk)
To: Arrigo Marchiori <ardovm@yahoo.it>
cc: Arrigo Marchiori via freebsd-fs <freebsd-fs@freebsd.org>
Subject: Re: Random truncated files on USB hard disk with timeouts;
 how to debug?
In-reply-to: <20161019064315.GB93031@nuvolo>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
References: <20161018152715.GC89691@nuvolo>
 <51997.1476812624@critter.freebsd.dk> <20161019062812.GA93031@nuvolo>
 <7759.1476858801@critter.freebsd.dk> <20161019064315.GB93031@nuvolo>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <7923.1476861738.1@critter.freebsd.dk>
Date: Wed, 19 Oct 2016 07:22:18 +0000
Message-ID: <7924.1476861738@critter.freebsd.dk>
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs/>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 19 Oct 2016 07:22:23 -0000

--------
In message <20161019064315.GB93031@nuvolo>, Arrigo Marchiori writes:

>> Y-cables are a big warning sign.
>> 
>> You can try plugging the "power-only" plug into a high quality 1
>> ampere USB charger, but that is no guarantee for success.
>
>Yes, I also thought so at first.
>
>But I also believe that if anything goes wrong at the hardware level,
>I should get a big warning from the kernel, instead of a funny
>apparently-truncated file, that returns to be readable at next
>reboot...?

Only if the drive finds out something is wrong and tells the kernel.

If the drive has bad power supply, that may not happen.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.