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	for linux-mtd@lists.infradead.org; Fri, 07 Mar 2008 06:12:02 +0000
Subject: Re: Powerfail-tests and jffs2-sync-mount
From: Artem Bityutskiy <dedekind@infradead.org>
To: =?ISO-8859-1?Q?Schl=E4gl?= "Manfred jun." <manfred.schlaegl@gmx.at>
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Date: Fri, 07 Mar 2008 08:10:46 +0200
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On Thu, 2008-03-06 at 17:41 +0100, Schl=C3=A4gl Manfred jun. wrote:
> Hi!
>=20
> I did some powerfail-testing of jffs2.=20
>=20
> Short overview (Contact me for details):
> Arch: ARM926EJ-S with 40MB rw jffs2 part on Samsung NAND-Flash
> Kernel: linux-2.6.12 (a little bit out of date, i know ;-))
> Test:=20
>  * Target-Loop
>    * filesystem-consistency:
>      * create dir
>      * copy data(> eraseblock-size) to new file
>      * delete a file
>    * file-consistency:
>      * logfile on jffs-part (simply appending text with echo)
>  * External random-time reset:
>    * external uC
>    * generates reset every 120+rand(0..30) seconds
>  * Run until no more space on filesystem
> Results:
>  * test with sync-mounted jffs2 (mount -o sync):
>    * duration 4:40 hours
>    * 131 generated resets
>    * consistent FS
>    * consistent logfile
>  * test with async mounted jffs2:
>    * duration 4:10 hours
>    * 118 generated resets
>    * consistent FS
>    * corrupted logfile (bad-chars, etc.)
>=20
> Now my question: Are there any non-obvious disadvantages, mounting jffs2
> synchronal, except lower speed and a little(depends on usage) decreased
> flash-life-time (wear-out), or is this anyway the default approach?

My understanding of the things is that this should not really matter. I
thought if you have some corruption in asynchronous mode, you should
have them in synchronous too, may its worth trying more synchronous mode
testing?

--=20
Best regards,
Artem Bityutskiy (=D0=91=D0=B8=D1=82=D1=8E=D1=86=D0=BA=D0=B8=D0=B9 =D0=90=
=D1=80=D1=82=D1=91=D0=BC)