From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: power loss -> corruption Date: Thu, 08 May 2003 22:58:35 +0400 Message-ID: <3EBAA8DB.3080202@namesys.com> References: <200305081348.42359.Dieter.Nuetzel@hamburg.de> <200305081502.47455.Dieter.Nuetzel@hamburg.de> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Mirar Cc: =?ISO-8859-1?Q?Dieter_N=FCtzel?= , reiserfs-list@namesys.com You have run into the disadvantage of meta-data journaling, which is that files that you are writing to may be corrupted if you crash. This disadvantage exists for performance reasons: using traditional journaling approaches such as V3 uses, if you journal the data you must write it twice. V3 also offers you the option of performing ordered writes, in which, if I remember right, metadata is only updated after the data reaches disk. V4 uses a completely different technology we call wandering logs, in which every filesystem operation is performed as a fully atomic transaction, and because of its new design, there is very little performance cost (in fact, reiser4 is higher performance than V3). We hope V4 will be ready for prime time sometime this summer. -- Hans